USF Libraries
USF Digital Collections

Evaluation of pile driving lead section


Material Information

Evaluation of pile driving lead section
Physical Description:
Uslu, Kadir
University of South Florida
Place of Publication:
Tampa, Fla.
Publication Date:


Subjects / Keywords:
lead connection
principle strain stress
load displacement
capacity of lead
Dissertations, Academic -- Civil Engineering -- Masters -- USF   ( lcsh )
government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
theses   ( marcgt )
non-fiction   ( marcgt )


ABSTRACT: Driving piles constitute a large portion of the high-capacity foundations used today. They transfer structural loads to deep bearing strata when adequate surficial soils are not available. The mechanisms required to install these piles generally consist of a hammer, hammer lead, a crane, and various support rigging. This study focused on lead sections, specifically, one which was manufactured by Berminghammer Foundation Equipment, Inc. The dimensions and strength of a lead section must be capable of supporting both the pile driving hammer and the longest anticipated pile for a given site. The strength of the section must be capable of withstanding hundreds of tons in compression and bending. If the lead is operated in a batter, (tilted forward, backward, or sideways) the weight of the hammer and pile causes much more bending than the vertical orientation. The cross-section details for these long steel sections vary from design to design but usually incorporate some form of bolt group, pins, and steel alignment dowels. This thesis focuses on the design, modeling, and testing of such a connection. The motivation of the study stems from a company-wide incentive to standardize the connections used to splice the Berminghammer C15-series lead section. In an effort to verify a proposed connection design, Berminghammer Foundation Engineering solicited the University of South Florida to test a full-sized lead section to failure, while monitoring the splice-connection performance.
Thesis (M.S.C.E.)--University of South Florida, 2003.
Includes bibliographical references.
System Details:
System requirements: World Wide Web browser and PDF reader.
System Details:
Mode of access: World Wide Web.
Statement of Responsibility:
by Kadir Uslu.
General Note:
Title from PDF of title page.
General Note:
Document formatted into pages; contains 161 pages.

Record Information

Source Institution:
University of South Florida Library
Holding Location:
University of South Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
aleph - 001447472
oclc - 54089582
notis - AJN3916
usfldc doi - E14-SFE0000212
usfldc handle - e14.212
System ID:

This item is only available as the following downloads:

Full Text


Evaluation Of Pile Driving Lead Section by Kadir Uslu A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering Department of Civil and Environmental Engineering College of Engineering University of South Florida Co-Major Professor: Austin Gray Mullins, PhD. Co-Major Professor: Ashraf Ayoub, PhD William Carpenter, Ph.D. Date of Approval: November 4, 2003 Keywords: lead connection, principle strain-stress, load displacement, capacity of lead, modeling Copyright 2003 Kad ir Uslu


i Table of Contents List of Tables. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv List of Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vAbstract. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xChapter 1 Introduction ................................................... 1 1.1 Overview .................................................... 1 1.2 Organization .................................................. 3 Chapter 2 Literature Re search ............................................. 4 2.1 Pile Types ................................................... 5 2.1.1 Concrete Piles ......................................... 5 Reinforced C oncrete ............................ 5 Prestressed S quare or Round Piles .................. 6 Concrete Cylinder Pile (Post Tensioned) ............. 7 2.1.2 Steel Piles ............................................ 8 Steel Pipe Pil e ................................. 9 Steel HP, W Piles .............................. 10 2.1.3 Sheet Piles ........................................... 11 Timber Sheet Piling ............................ 11 Steel Sheet Piling .............................. 11 Concrete Sheet Piling ........................... 12 Composite Sheet Piles .......................... 12 2.1.4 Timber Piles ......................................... 13 2.2 Hammer Types ............................................... 14 2.2.1 Drop Hamme rs ....................................... 15 2.2.2 Steam and Dies el Hammers ............................. 15 2.2.3 Vibratory Ham mers .................................. 16 2.2.4 Pneumatic Ham mers or Air Hamme rs ..................... 16 2.2.5 Hydraulic Ham mers ................................... 16 2.2.6 Jetting Piles .......................................... 16 2.2.7 Other Types of Hammers -Fondatec ....................... 17 2.3 Hammer to Pile D etails ........................................ 18 2.3.1 Helmets, Doll y, Packing, Driving C ap, Pile Gate ............ 18 2.4 Positioning Equipment ......................................... 19


ii 2.4.1 Piling Frames ........................................ 20 2.4.2 Trestle Guides ........................................ 21 2.4.3 Vertical Leads ........................................ 21 Chapter 3 Experimen tal Program .......................................... 32 3.1 Overview .................................................... 32 3.2 Test Setup .................................................. 33 3.3 Instrumentation .............................................. 35 3.3.1 Strain Gages .......................................... 35 Strain Gage Specifications ....................... 35 Strain Gage instrumentation ..................... 36 Test Set up ................................... 41 3.3.2 LVDT .............................................. 44 Principle of Operation .......................... 45 Construction .................................. 45 Transformer .................................. 46 Open Wiring LVDT ............................ 46 Ratiometric Wiring LVDT ....................... 46 3.3.3 Hydraulic Jacks ....................................... 47 3.3.4 Data Acquisitio n System (Megadac) ...................... 47 3.4 Running the test .............................................. 50 Chapter 4 Experimen tal Results ........................................... 65 4.1 Overview ................................................... 65 4.2 Principle Strain-S tress-Angle ................................... 66 4.3 Load-Displacement ........................................... 72 Chapter 5 Numerical Modeling ........................................... 96 5.1 Introduction ................................................. 96 5.2 Defining Geom etry ........................................... 96 5.3 Defining Eleme nt Types ....................................... 98 5.3.1 BEAM4 Element Type ................................. 98 5.3.2 SHELL63 Element Type ................................ 99 5.3.3 BEAM24 Element Type ............................... 100 5.4 Defining Real Constant ....................................... 101 5.5 Defining Material P roperties ................................... 103 5.5.1 Linear Material pr operties ............................. 103 5.5.2 Nonlinear Materi al Properties ........................... 104 5.6 Defining Mesh .............................................. 104 5.7 Applying Load and Obtain The Solution .......................... 106 5.7.1 Applying Load ...................................... 106 5.7.2 Obtain The Solution .................................. 107 5.8 Modeling and Experimental Results Comparison ................... 107


iii Chapter 6 Conclusion .................................................. 117 References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119Appendices. . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . 121 Appendix A. . . . . . . . . . . . . . . . . . . .. . . . . . . .122 Figure A1 Positioning with Europan Type Lead ................. 122 Figure A2 U-Type Lead Section with Pin Connection. . . . . . . 123 Table A3 Different Types of Lead Section ...................... 124 Table A4 Properties of C15-C12 Lead sections .................. 125 Appendix B. . . . . . . . . . . . . . . . . . . .. . . . . . . .126 Table B1 Air-Activated oil and fuel injection B -2005 Hammer ..... 126 Table B2 Air-Activated Oil Fuel Injection B-3005 ............... 127 Table B3 Air-Activated Oil and Fuel Injection B -3505 Hammer .... 128 Table B4 Air Activated Oil and Fuel Injection B -4005 Hammer ..... 129 Table B5 Air-Activated Oil and Fuel Injection B -4505 Hammer .... 130 Table B6 Air-Activated Oil and Fuel injection B -5005 Hammer .... 131 Table B7 Air-Activated Oil and Fuel Injection B-5505 ............ 132 Table B8 Air-Activated Oil and Fuel Injection B-6005 ............ 133 Table B9 Air-Activated Oil and Fuel Injection B -6505 Hammer .... 134 Table B10 dcp Diesel Hammer(HPH 1200) ..................... 135 Table B11 dcp Diesel Hammer(HPH 2400) ..................... 136 Table B12 Delmag Di esel Hammers .......................... 137 Table B13 Diesel Hammers Comparison ....................... 138 Table B14 Standard Fre quency Vibrators ...................... 139 Table B15 Vibratory H ammers ............................... 140 Table B16 Vibratory Hammer Comparison ..................... 141 Table B17 ICH Hydrau lic Hammer ........................... 142 Table B18 HPI & MENCK Hammer .......................... 143 Table B19 Vulcan Air H ammer .............................. 144 Table B20 HPSI Hydra ulic Hammer .......................... 145 Appendix C. . . . . . . . . . . . . . . . . . . .. . . . . . . .146


iv List of Tables Table 4.1 Summary of Prominent LoadStrainLocations. . . . . . . . . . . . .72 Table 4.2 Moment of Inertia Calculations For Ixx. . . . . . . . . . . . . . . 75Table 4.3 Moment of Inertia Calculations For Iyy. . . . . . . . . . . . . . . 75Table 4.4 Moment of Inertia Calculations with Holes For Ixx. . . . . . . . . . . 76Table 4.5 Moment of Inertia With Holes For Iyy. . . . . . . . . . . . . . . . 76Table 4.6 Moment of Inertia With Holes For Second Section of Iyy. . . . . . . . 77 Table 4.7 Moment of Inertia of Spigot and Bolts(Connection) of Ixx. . . . . . . . 78 Table 6.1 Allowable Hammer Weights for C15. . . . . . . . . . . . . . . . 118


v List of Figure Figure 1.1 Pile Driving Equipment .......................................... 1 Figure 2.1 Concrete Pi les ................................................ 26 Figure 2.2 Post-Tensi oned Piles ........................................... 26 Figure 2.3 Steel Pipes ................................................... 27 Figure 2.4 HP Steel Pil es ................................................ 27 Figure 2.5 Sheet Piles ................................................... 28 Figure 2.6 Diesel Hydr aulic .............................................. 28 Figure 2.7 Vibratory H ammers ............................................ 29 Figure 2.8 Mc Air Ham mer .............................................. 29 Figure 2.9 Hydraulic H ammer ............................................ 30 Figure 2.10 Driving C aps and Helmets ..................................... 30 Figure 2.11 Pile Gate ................................................... 31 Figure 3.1 Lead Connection ............................................... 53 Figure 3.2 Spigot and B olts ............................................... 53 Figure 3.3 Holes on The Lead For Instrumentation ............................. 54 Figure 3.4 Placin g Under The Frame ........................................ 54 Figure 3.5 Placing Lead ................................................. 55 Figure 3.6 Loading 60 From The Center .................................... 55 Figure 3.7 LVDT For Middle Displacement .................................. 56


vi Figure 3.8 LVDT For Displacement ........................................ 56 Figure 3.9 Permanent Displacement ........................................ 57 Figure 3.10 Connectio n with 12 Bolts ....................................... 57 Figure 3.11 Bottom Displacement(LVDT) ................................... 58 Figure 3.12 Support 25" From End ......................................... 58 Figure 3.13 Strain Gage Locations ......................................... 59 Figure 3.14 Strain Gages on The Spigot ..................................... 59 Figure 3.15 Hydraulic Jacks .............................................. 60 Figure 3.16 Applying Nodal Load .......................................... 60 Figure 3.17 Load Cell ................................................... 61 Figure 3.18 Pin Suppo rt .................................................. 61 Figure 3.19 Deform ation Under The Load ................................... 62 Figure 3.20 STB Layout ................................................. 62 Figure 3.21 Permane nt Gap ............................................... 63 Figure 3. 22 Permanent Displacement ....................................... 63 Figure 3.23 No Distort ion on Face ......................................... 64 Figure 4.1 Lvdt1 Load-Displacement Curve .................................. 82 Figure 4.2Lvdt2 Load -Displacement Curve .................................. 82 Figure 4.3 Lvdt3 Load Displacement Curve .................................. 82 Figure 4.4 G1 Principl e Stress-Angle and Loa d ............................... 83 Figure 4.5 G1 Strain-L oad ................................................ 83 Figure 4.6 G2 Principl e Stress-Angle and Loa d ............................... 83


vii Figure 4.7 G2 Strain-L oad ................................................ 84 Figure 4.8 G3 Principl e Stress-Angle-Load .................................. 84 Figure 4.9 G3 Strain-L oad ................................................ 84 Figure 4.10 G4 Princip le Stress-Angle and Loa d .............................. 85 Figure 4.11 G4 StrainLoad .............................................. 85 Figure 4.12 G5 Princip le Stress-Load ....................................... 85 Figure 4.13 G5 StrainLoad ............................................... 86 Figure 4.14 G6 Princip le Stress-Angle and Loa d .............................. 86 Figure 4.15 G6 StrainLoad ............................................... 86 Figure 4.16 G7 Princip le Stress-Angle and Loa d .............................. 87 Figure 4.17 G7 StrainLoad ............................................... 87 Figure 4.18 G8 Princip le Stress-Angle and Loa d .............................. 87 Figure 4.19 G8 StrainLoad ............................................... 88 Figure 4.20 G9 Princip le Stress-Angle and Loa d .............................. 88 Figure 4.21 G9 StrainLoad ............................................... 88 Figure 4.22 G10 Principle Stress-Angle and Load ............................. 89 Figure 4.23 G10 Strain -Load .............................................. 89 Figure 4.24 G11Princ iple Stress-Angle and L oad .............................. 89 Figure 4.25 G11 Strain -Load .............................................. 90 Figure 4.26 G12 Princ iple Stress-Angle and L oad ............................. 90 Figure 4.27 G12 Strain -Load .............................................. 90 Figure 4.28 G13 Upwa rd Principle Stress-Ang le and Load ...................... 91


viii Figure 4.29 G13 Down ward Principle StressA ngle and Load ................... 91 Figure 4.30 G13 Strain -Load .............................................. 91 Figure 4.31 G14 Principle Stress-Angle and Load ............................ 92 Figure 4.32 G14 Strain -Load .............................................. 92 Figure 4.33 G15 Princ iple Stress-Angle and L oad ............................. 92 Figure 4.34 G15 Strain -Load .............................................. 93 Figure 4.35 G16 Princ iple Stress-Angle and L oad ............................. 93 Figure 4.36 G16 Strain -Load .............................................. 93 Figure 4.37 Deformation on Spigot ......................................... 94 Figure 4.38 Moment-D isplacement Diagram ................................. 94 Figure 4.39 Moments & Moment of Inertia .................................. 95 Figure 5.1 Connection Key Points ......................................... 109 Figure 5.2 B24 Thin B eam Example ....................................... 109 Figure 5.3 B24 Thin Beam in Design ...................................... 110 Figure 5.4 General Mesh & 7630Shell Elements ............................. 110 Figure 5.5 Connection Mesh & 21 Beam Elem ents ........................... 111 Figure 5.6 Load-Middle Displacement Comparison Between Experiment and Feap 111 Figure 5.7 Load-Displacement Lvdt1 Comparison Between Experiment and ANSYS 112 Figure 5.8 Deforme d Shape ............................................. 112 Figure 5.9 Connection Displacement ....................................... 113 Figure 5.10 G1 Principle Strain .......................................... 113 Figure 5.11 Normal S train Z Direction Princi ple Strain ........................ 114


ix Figure 5.12 G1Princip le Stress ........................................... 114 Figure 5.13 Principle S tress .............................................. 115 Figure 5.14 XZ Shear ................................................... 115 Figure 5.15 Shear YZ ................................................... 116


x Evaluation of Pile Driving Lead Section Kadir Uslu ABSTRACT Driving piles constitut e a large portion of the h igh-capacity foundati ons used today. They transfer s tructural loads to deep b earing strata when adeq uate surficial soils are not available. The mechanisms required to install these piles generally consist of ahammer, hammer lead, a crane, and various support rigging. This study focused on lead sections, specifically, one which was manufactured by Berminghammer F oundation Equipmen t, Inc. The dimension s and strength of a lead section must be capab le of supporting both t he pile driving hamm er and the longest anticipated pile for a given site. The strength of the section must be capable of withstanding hundreds of tons in compression and bending. If the lead is operated in a batter, (tilted forward backward, or sideway s) the weight of the ham mer and pile causes much more bending than the vertical orientation. The cross-section details for these longsteel sections vary from design to design but usu ally incorporate some form of bolt group, pins, and steel a lignment dowels. This thesis focuses on the design, modeling, and testing of such a connection. The motivation of the study stems from a company-wide incentive to standardize the connections used to spl ice the Bermingham mer C15-series lead se ction. In an effort to verify a proposed conn ection design, Bermi nghammer Foundat ion Engineering solicit ed


xi the University of Sout h Florida to test a full-s ized lead section to fail ure, while monitoring the splice -connection perform ance.


1 Figure 1.1 Pile Driving Equipment Chapter 1 Introduction 1.1 Overview Driven piles constitute a large portion of the high-capacity foundations used today. They transfer structural load s to deep bearing strata w hen adequate surficial soils are not available. The mechanisms required to install these piles generally con sist of a hammer, hammer lead, a crane, and various support rigging. Figure 1.1 shows the basic elements of the pile driving equipment the sketch.


2 This study focused on lead s ections, specifically, one which was man uf actured by Berminghammer Foundation Equipment, Inc. The dimensions and strength of a lead section must be capable of supporti ng both the pile driving hammer and the long est anticipated pile for a given site. Hence, the common length can be from 25 to 55 feet; in exceptional cas es, it may reach 200 feet. The strength of the section must be capable of withstanding hundreds of tons in compression and bending. If the lead is opera ted in a b atter, (tilted forward, backward, or sideways) the weight of the hammer and pile causes much more bending than the vertical orientation. A s the extreme lengths c annot be r eadily trucked, the lead s are assembled on-site from a series o f shorter segments (a pproximat ely 40 feet or less). The cr os s-section details for these long s teel sections vary from design to design but usu ally incorporate some for m of bolt group, pins and steel alignment d owels. This thesis focuses on the d esig n, modeling, and testing of such a connection. The motivation of the study stems from a company-wide incentive to standardize the connections used to splice the Berminghammer C-series lead section. In an effort to verify a pr oposed connection design, Berminghammer Foundation Engineering solicited the University of South Florida to test a full-si zed lead section to failu re while mo nitoring the spliceconnection perform ance. This study involved a literature search of pile-driving equipment and modeling of the propos ed secti on in both linear and non-linear range. Full-scale testing of a proto-type section was conducted and c omparisons were made between the theor etical values with those measured.


3 1.2 Organization The bo d y of the thesis is organi zed into six chapters: th is chapter (Chapter1) pr ovides the essence of the problem statement; Chapter 2, a literature review abou t pil e driving ; Chapter 3, an overv iew of the experimental program; Chapter 4, analysis of the experimental results; Chapter 5, analytical modeling in ANSYS and Feap. Finally, conclusions are provided and discussed in Chapter 6.


4 Chapter 2 Literature Research The installation of driven pile foundation s started with man-powered drop ha mmers th at drove timber piles. The effectiveness of pile foundations led to the evolut ion o f mechanized pile drivi ng equipment. The development of pile driving equipment evolved in various parts of the world and this d evelop ment depended mainly on the influence of the local ground conditions. For example, the stiff clays of the Mid-Western states of the United States an d the Great Lakes region of Canada favored lar ge diameter bored pile s; as a resu lt m obile rotary drilling machines were developed for the ir installation. By cont rast, the presence of hard rock in the shallow depths of the New York area favored the continuing development of the r elatively slender shell pile driven by an internal mandrel. The growth of the offshore oil industry in many parts of the world necessitated the development of an entirely new range of massive single acting steam hammers designed f or dr iving large diameter steel piles guided by tubular jacket structures.[1] Modern pile driving equipment requires several primary components of which each has multiple variations. These variations address different pile types, hammer type s, hammer components, crane connections, pos itioning equipment an d lead sections. A brief sum mary of each is provided in th is chapter.


5 2.1 Pile Types Deep foundations are synonymous with piles to the extent that they both encompass cast-in-place and precast concrete as well as timber and a multitude of steel se ctions. Castin-pla ce systems include all f orms of bored piles su ch as drilled shafts, au ger-cast i n-sit u piles (continuous flight aug er piles), Frankie piles, etc. In the United States, the term pile has the connotation of driven pile, which is the focus of this study.[19] 2.1.1 Concrete Piles Driven concrete piles are used in all environments. Th ey are re latively co rrosion resistant and are the only long-term foundation found in mar ine environments. Therein, pr estressed piles have proven durable for numerous decades of service with the exception of certain acid organic soil s, concrete piles are consid ered, to be permenant They are limited to under 200 ft. in length due to weight and practicality. Pre-cast sections encompass all concrete driven piles th at are “cast” (fabricated/poured) in a specialized form-work prior to installation. These sections include reinforced, prestressed, and post te nsioned co ncre te with numerous cros s-sectional variations. Reinforced C oncrete Piles are produced and cured in specified lengths and transfered to the construction site. Precast piles may be m ade with ordinary reinf orcement and are desi gned to resist bending stress during lifting and transporting to the site. Likewise, they must resist bending moments from lateral loads and provide sufficient resistance to vertical loads as well as any tension loads developed during driving. [14] Figure 2.1


6 Typically, the reinforced steel in a normal reinforced concrete pile makes up 1-3% of a cross-sec tion area of the pile. Driving stresses include both tensile and compressive load s w hich can diminish the i ntegrity of the pile. Th e required reinforcem ent must adequately reduce the chances of tensile fracture. Prestressed S quare or Round Piles The term prestressed in actuality refers to the state of the concrete prior to any form of loading. As such, it inc ludes both prestressed steel and po st tensioned steel, which further specify the state of the steel relative to when the concrete was poured and cured. Therein, “prestressed” concrete has the connot ation of all concrete sec tions cas t an d cured around stretched steel. “Post-tensioned ” concrete implies that some form of duct work is cast into the concrete during fabric ation. This duct provid es a p athway for the placement of reinforcing steel, after the concret e is cured. The steel is th en stretched by jacking against and precompressing the co ncrete. Grout, which is then injected in to the duc ts, cures and then provides a backup mec hanism to maintain t he precompression sh ould the p rimary anchorage fail. In “prestressed” piles, high strength steel(f ult =1700-1860MPa) and pre stressed cable s are brought to a value on the order of 0.5 to 0.7 f ult (800-1000MPa). This stee l makes up between 0.5 and 1 % of the crosssectional area. Afte r hardening/curing, the prestressed cables are cut, and the tension f rom the cable produce s compressive stress in the concrete pile as the steel attempts to return to its un-stretched lengt h. The piles are shorten ed under the initial prestress compression load, Pi, and concr ete undergoes cre ep, which causes so me relaxation in the steel. Since thes e prestress loss es cannot be evalu ated precisely, a lump


7 sum loss value of 24 0MPa is accepte d. The stress range in the steel is 500-700MPa. The goal is to produce a final compressive stress in the concrete from prestressing on the order of 4-6MPa. This allows the concrete to resist tensile stresses during driving up to the sum of prestress and the concrete tensile strength (4-6MPa+fe). Given the control in fabrication, high strength concrete (35-55Mpa) can be used with confidence. The allowable design load P a based on the p ile material for prestressed piles and prestress loss due to loa d and creep can be comp uted as: Pa = A g (0.33f`c 0.27fpe) Where Ag is gross total area, fpe is effective prestress after all losses (roughly 5MPa is typical). Another important issue is placement of picking points for prestressed piles since the computed bending s tress is f = M/S < f pe where M can vary accordi ng to the pick points. If this concern is satisfied the pile sho uld not develop excessi ve tension stress during either handling or driving. “Prestresse d” piles ar e usually no greater than 30" in dimension.[14] Concrete Cylinder Pile (Post Tensioned) In contrast, “post-tensioned” cylinder piles can have an enormous range up to 72" due to the large inner diameter w hich reduces humidity weight tremendously These piles result in high density concrete with th e highest quality. Also these piles are manufactur ed in 16 feet in length using the spinning method of fabrication. Figure 2.2 The 16 feet length cylinder s are th en prestressed together with low relaxation pre stressing strands to fo rm cylinder piles up to over 100 feet long. The effective prestress in the piles should be 1,200 psi and prestressing steel sh ould be 7-wires strand, grade 1860 meeting the requirements of ASTM A416M. Also, minimum concrete strength shoul d be 7,000 psi at 28 days and all


8 pile reinforcement and do wels used in pile connections and build-ups should be epoxy coated to meet the requirem ents. Material use d t o abut the joint surface s of individual sections shall be an epo xy resin resistant to exposure and weathering, meeting the requirements of ASTM C881, Type I Grade 3, class suit able for use at the ambient temperature at time of its application. Compressive strength of the cured epoxy at 28 days s hall not be less than the min imum specified 28 day compressive str ength of th e concrete(7000psi). The advantageous of t his type of pile is gener ally le ss perm eable than reinforced concrete piles and may be expected to exhibit superior performance in a marine environment. Also, hard steel points (fixed or attach able drivi ng shoes) can be used at the toe of jointed piles for pr otection when penetrat ing soils contai ning boulders, or in we ak rock.[22] 2.1.2 Steel Piles Steel has a great advantages as a material in pile driving. The high strength of st eel gives high resistance in bendi n g lateral loading, and heavy compression. There is almost no depth to which a steel pile cannot be driven wi th proper equipment and consid eration to buckling. As such, most deep w ater oil rigs are founded on either steel piles or an chored to the sea bottom with some kind of anchor. The deterioration of st eel piles from corrosi on is the most serious factor to be considered when using steel. Ther efore, steel piles are not used for long-term marine ex posure. However, ther e are various ways to minim ize the adverse effects of corrosive environments such as painting, encasing with concrete, adding copper to the steel, and cathodic protection.[20]


9 The most common usage of steel piles are pipe and H-section types. T he former are extens ively used in underpinning work with small diameters and the latter in situations where upheaval of the surrou nding soil would dama ge the adjoining proper ty, or where very deep penetration is required though loose or medium-dense sands.[21] Steel Pipe Pil e Pipe piles are either welded o r seamless steel piles. They can be driven eithe r open end or closed end. Fig ure 2.3 In bot h cases, they can be fill ed with concrete after installation. However open-ended pipe piles a re not filled with concr ete as they often fill with soil during driving. In some instances, the upper po rtion of pipe piles (ope n or closed ended) may be cast into a footing which will require some form of dowel connection.An open-end pile is also con si dered a s mall volume displacement pile; however, a plug forms inside at a depth o ne or more meters below the outside ground levelfrom the combination of inside perimeter friction and t he driv ing vibration. This plu g is invisible during driving due to pile cap an d hammer interferen ce until the pile reaches its final driving depth. The sub-soil layer may be remolded based on the volume of the plug. Also, open end pipe piles have an advantage of surface entry as it can break up boulders encountered by either using chopping, drilling, or blasting, and remove the rock fragments. Splicing in pipe piles is done the same way as steel columns, by either welding or bolting. In general, slices are prefabricated (and patented) splice connectors. There are two types of connections, whic h are either inside or outside sleeves to connect the two pipes. If the sleeve is located inside first, the top of the lower pipe and the bottom of the upper pipe should be fully welded while the sleeve is inside, or the s leeve can be placed on th e lower


10 pipe and the upper pile can be placed in through the sle eve. Generally, these t ypes of splices provide extra strength against compression, tension, bending, and shear. [14] Steel HP, W Pil es In the job market, stee l piles have three types th at differ mainly in thickness of flange and web The flange and web of HP piles have equal thic kness. The flange is th icker than the web in W shape piles. The HP type is the most common pile type used in existing job market. Figure 2.4 Flange and web have an effect on displacement. An HP pile`s section does not have a large area and it generates onl y a sm all volume displacem ent. Since HP piles are extremely rigid, they will either break or displace boulders should they encounter them. Other characteristics of piles include spli ces. Splices in HP piles can be prefabricated from two channels of adequate length back to back with a short spa ce where the top pile section rests. The splices are th en welded to t he web. If the top steel pile is adequately embedded in the cap (150mm or more), special load transfer plates are no t n eeded. If embedment is limited for special purposes, the steel plates can be welde d on top of the pile to assist in the load transfer and ensure that the pile and pile cap act together. HP piles may require reinf orcement to penetrate hard soils with boulders to prevent excessive tip damage. These tip s are more economica l due to the a ssociated labor and fabrication costs except in isolated cases where only one or two tips might be needed. The major problem with steel piles is corrosion. Piles exposed to saltwater or e ffluents with a pH much above 9.5 or a pH below 4 will require protection like painting, concre t e encasement, and for splices, a larger section can be us ed in a corrosive zone. The re are also


11 newer grades of high str ength and copper alloy s teels, which are two or t hree times more resistive against corrosion than A36 grade steel. The allowable design load for steel pi le is: P a =Apf s where Ap is cross-sectio n area, and fs is allowable s teel stress in range of 0.33 to 0.5xf y (according to code or specification).[14] 2.1.3 Sheet Piles There are four types of sheet piles according to its materi al, which are timber, steel, reinforced concrete, a nd a combination of t hese materials. Figure 2.5 Timber Sheet Piling Timber sheet piling is sometimes used as a free standing wall wh ose height is less than 3m, and is mostly used for temporarily braced sheeting to prevent cave-ins during the deep water and sewer line ins tallations. When it is u sed as a permanent structure, a preservative treatment is necessary, even though the maximum life of treated timber shee t piles are 10 to 15 years. Tim ber sheet piles can also be used as low w alls when treated with wood preservatives along the water front. Event ually the wall is covered by sand from the tidal action, and with the proper treatment the wood will last long enough to accomplish the p ur pose of wall. The soil type is very important for timber piling because during driving, a cap may be necessary t o reduce tip damage. I f the soil is hard, grave lly, in order to avoid tip damage water jet can be used to predrilled a hole to reduce the driving resistance.[14] Steel Sheet Piling Steel sheet piling is the mos t common type becau se of its many advant ages. It can resist high driving stresses developed in hard or rocky soil; it is relatively light and p ractical


12 to move; it can be reused several times; its service life is relatively long; it is very easy and pract ical in usage; and it may be extended by either weld ing or bolting. Moreove r, steel piling joints are less apt to d efo rm when wedged full with soil and small stones during driving. There are different connection details for s heet piling such as ball socket, thumb and finger.[14] There are also differe nt types of sections tha t a re used d epending upon the varying strengths. For instance Z sections are used wher e the large bending mo ment requires a l arge moment of ine rtia or section modulu s. Besides that, if the s tiffness ca pacity of Z becomes insufficient for d riving, the box se ction or the soldi er Z pile comb ination ca n be used. Concrete Sheet Piling These can be precast con crete members with a tongue and groove join t. Since they have a huge mass, handling and driving stresses must be taken in to account. The points are cast with a bevel, which tends to wedge the pile being driven aga inst the previously driven pile. Dimensions are generally very bulky ; therefore while drivin g they will displace a huge volume of soil. As a result, co ncrete piles are not competiti ve like steel sheet piles u nless they are produced somewhere besides on the job site.[14] Composite Sh eet Piles Sometimes walls can be constructed using a comb ination of two materials; for example soldierwood lagging, or soldier beams of th e same width along with sheet piling, which can be used between the spacing. For co rro sion protection, one might encase the upper part of steel sheet pilin g in concrete after it is driven, with the concrete extending from


13 below the water line to the pile top. The lower part of sheeting can be steel for durability, but the upper part can com posed of wood or conc rete. As an other example of the general application of waterfront wa lls is composite construct ions which are a compo sition of soldier beams and sheet piles or build up box pile sections.[14] 2.1.4 Timber Piles Timber piles are made of tree trunks with their branches carefully trimmed off, and usually treated with a preservative, and driven with the small end although sometimes large ends are used in very soft soil. Timber piles are used mostly in North America, China, and Scandinavia. Because of their flexi bility and lightness, tim ber piles are used for tem porary works especially in Great Brit ain. If timber is repea tedly not exposed to m oistu re or to extremely low-humidi ty, they ca n have a long life, but u nfortunately it is diff icult to maintain them under those adve rse c ond itions. Adding to this difficulty are the effects of insect and fungi damage to the wood. Therefore, care in selection and trea tment can decrease the frequency of attacks and the resulting damage. Examples of suitable timber include douglas fir, parana, pitch pine, larch, and western red cedar are in the soft wood class, and greenheart, jarrah, opepe, teak, and European oak are in the hardwood class. When assessing types, driving depths below th e ground level may req uir e concrete or creosote protection. The New York Foundation Code permits safe wor king stresses of 5 .9N/mm2 on the net area of ceda r. Norway pine, spruce, and other similar woods are 8.3 N/mm2. In hard soil s, in order to prevent pile damage during driving, a shoe is requ ired. In dif ficult driving conditions, jetting or pre boring a hole for the pile could be adapted rather than risking the undetected sp littin g or breakage of piles b elow the ground level. T he average length is


14 between 6 to 15 m. Timber pil es may be spliced if lon ger len gths are required. Avoiding middle sp licing is advised since sagging and distortion is maximum in the middle of the length. [15] 2.2 Hammer Types In pile driving, it is im portant to select a piling hammer. In order to s elect hammer type, it is necessary to consider the weight of pile and characteristics of the ground in which the pile is to be driven. Sing le-Acting and Double-A cting Hammers and D iesel Hammers are effective on all soil ty pes. Besides the value o f energy per blo w, the striking rate, fu el consumption, and sometimes noise of pile driving affects the selection of the hammer type. The valu e of energy pe r blow helps to assess the weight of the pile and the penetration of pile or the ultimate r es istance. The dynamic pile driving formula can help formulate the rough assessment energy value at the time of driving. H o wever, the manufact urer’s rated energy per blow may not always be reliable. The efficiency of a hammer may be very low if its maintenance is don e poorly or it is operated improperly. Also, packing inserted between pile and the hammer, and condition of packing material especially after a period of driving aff ects the energy. The rate of striking of a hammer depends on the resistance of t he pile head packing condition and pr essure of the stem or a ir pressure. The manu facturers maximum striking rate is b ased on hard driving resistance when the hammer or ram tends to bounce on well maintained equipment.[1] Five types of hammers e xist for driving piles. These are: Drop Hammer, S team and Diesel Hammers, Vibrator y Hammers, Pne umatic Hammers o r Air Hammers, Hyd raulic Hammers, and othe r types.


15 2.2.1 Drop Hammers Th e mass for Drop Ham mers is between 3 to 5 tons for driving precas t concret e piles, but for timber it is between 1 to 3 tons. The cross-section of hammers is normally 0.4 m 2 The mass can be one or two times more than total weight of the pile, and the minimum mass should be at least 3 tons f or 20-25 meter concret e piles. Also, for very long concrete piles the rate should be 30-40 times more than weight of pile per meter, prefer ably 4-5 tons. For timber piles, the mass should exceed twice the weight of the pile, the helmet and the follower, and the longer the hammer, the more concentrically the strike.[11] Figure 2.6 2.2.2 Steam and Diese l Hammers Stea m and Diesel Hamm ers are not convenient to use for soft clays. T he mass i s supposed to be larger than half of the total pile weight. The stem pressure is used in a SingleActing Steam Hammer to lift the ram that fa lls freely on the pile. T he stream pressure also can be used for the downward stroke of the hammer, w hich is called the Double–Acting Steam Hammer. In Double-Acting Steam Hammer, the striking velocity and blow intensity increases the penetration resistance of the pile. While drivin g, if the pile reaches the rocks, the blow intensity increase s two-fold. As a result the pile can be damaged, and the average blow rate is 40 to 60 blows/min. The Dies el Hammers is slow in soft clay where the driving resistance is low, and t he next blow does not start Therefore, the Diese l Hammers are prefera ble for cohesionless soil (sandy or silty soils or granular soils like gravel) and stif f clays. A lso when driving is don e from a floating bar ge it is advantageous to u se diese l hammers.[11] Figure 2.7a-b-c


16 2.2.3 Vibratory Hamme rs Vibratory Hammers are generally used i n loose or medium-d ense granular soil The Vibratory Hammers are us e d to drive both concrete a nd steel pile under diff icult soil conditions (primarily in gravel, sand and silt). In loose medium dense gravel the vibratory hammers are more beneficial to use. The ultimate bearing capacity of the piles in sand, driven by vibratory hamme r is approximately one-half of the bearing capacity of dri ven piles by drop hammers for th e same depth. The Vib ratory Hammers are relativ ely less noisy and have a higher penetration rate, especially in cohesionless soi ls (sa nd and gravel). On the other hand, there are some d isadvantages in the connections between vibratory hammers and piles. In addition the Vibrator y Hammers always need special heavy equipm ent in order to be handled and lifted.[11] Figure 2.8a-b 2.2.4 Pneumatic Hammers or Ai r Hammers Generally, Pneumatic Hammers or Air Hammers are used primarily to drive rails and redrive the pile s. The efficiency of Pneu ma tic Hammers is to a large extent dependent upon the air consumption. The rate is 100 to 300 blows per minute.[ 11]Figure 2.9 2.2.5 Hydraulic Hammer s The biggest advantages of hydraul ic hammers are relati vely low noise level and high efficiency While Pneumatic Ha mmer s ar e used, noise is a serious problem, therefore different methods are employed t o reduce the noise levels. Hydraulic Hammers are much more efficient in controlling noise. [11] Figure 2.10 2.2.6 Jetting Piles Water jetting is used to displace the granular so il from beneath the to e of the pile, then the pile can be driven into the hole formed by jetting and therefore a hammer may not


17 be necessary. Jetting is ineffective for clay s oil; however, it is very useful for lar ge gravel and cobbles. The most effective method is central jetting pile, w hich helps the pile not to deviate off line. Nevertheless, the combination of jetting and hammering can be used in the sand and gravel and someti mes air can be used fo r jetting instead of water. The nozzle size of jetting is among the 25 ,50,75mm(1,2,3 in), and the quantity of water required for jetting a pile of 250 to 350mm (10 to 14in) in size range from 15 to 60lt/s(200 to 800gal/min) for fine sands through sa ndy gravel. Required pump press ure is supposed to be at le ast 5bars (75lb/in2). Open-ended steel tubul ar piles and box piles ca n be jette d by a pipe operated between the flanges. Larger diameter tubular piles can have ring of peripheral jetting pipes but the resulting pile fabricat ion costs are high. In some cases la rge volumes of water used in jetting may cau se problems to occur such as a loss of skin friction. Jetting should be stopped above the final penetra tion level, and th e rem aining depth, which is around one meter (three feet) which could be driven by a hammer. Jetting method is best sui ted f or granular, overburden to end bearing rock or some other material resistant to erosion by wash water. Figure 2.11 2.2.7 Other Types of Ha mmers -Fondatec Other types of pile driving hammers include compound hammer, the air-gun the linear oscillator, and th e vibratory-impact ha mmer. The compound hamme r utiliz es compress ed air and stem to raise t he ram and to accelerate its fall and its construction is simila r to that of the hydrauli c differential hamm er. On the down stroke, no add itio nal mo tive fluid enters the cyl inder; the downward accelerating force results from the expansion of the air or steam above the piston acting on the differential area.


18 The air-gun type utiliz es a sudden injection of highly compressed air to raise the hammer ram within a cylinder. Upon reaching the top o f its stroke, the ram is allow ed to fall free to impact upon the driving anvil. This typ e was developed for un der water operations. The linear oscillator type of hammer gets its energy from the rapi d short-s troke vertical oscillations of a piston or ram operating in a cylinder. In general, hydraulic power oscillates the piston and sometim es the hydraulic power is controll ed by an electric al system. Some types of hammers` s troke and frequency can be varied to adjust to driving cond itions. Also, there is another typ e of hammer which u tilizes compressed air instead of hydraulic fluids, and a floating pist on bo uncing on a cushion of air. This prolongs the f orce application, which is a characteristic similar to that of the diesel ham mer. The vibratory-impact ham mer utilizes both vibrations and direct im pact to achieve pile penetration and is powered by electric energy.[2] 2.3 Hammer to Pile Detail s Details that can found between the hammer and pile include helmets, driving caps, dollies, packing, and safety ga tes Each of these details are essenti al for the overall efficiency of pile driving. 2.3.1 Helmets, Dolly, P acking, Driving Cap, Pile Gate A cast steel helmet can be placed over on a pile head to hold the resilient dolly and packing, which are interposed between the hammer and the pile to prevent the shattering of the latter at the head. Figure 2.12a-b-c-d Another factor is that the helmet should fit around the pile loosely so that the pile can rotate without binding on the helmet. The Dolly is placed in a square recess in the top of the helmet. It is squ are at the base and rounded on the top. It c an consi st of either an elm blo ck for easy driving or an


19 hardwood block such as oak, green heart, pynkado or hicko ry for hard driving. This Dolly is set into the helmet and onto the grain. Dollies can also be plast ic. Plastic dollies are especially more suitable for har d driving concrete and steel piles. In addition, plastic dol lies can withstand more than other dollies in much heavier driving. A third type of dolly (no t wood or plastic) is micarta, which consists of a phenolic resin reinforced with laminations of cros s grain cotton canvas. The laminate layers can be bonded to aluminum pl ates o r placed between a top steel plate and a bottom hardwood pad. Packing can be placed between the helmet and the pile head to cushion further blows to the concrete. Packing can consist of coiled rope, hessian packing, thin timber sheet s, coconut matting, or sawdust i n bags. While driving packing should be ins pected, to check for any losses of resil ience. Driving ca ps are u sed for the heads of steel piles. Their purpose is to protect the hammers more than steel pile. The undersides of driving caps for box and H section piles have projecting lugs to get in to the head of the pile. T hese projections are m ultiple and they are designed to fit piles over a range of diameters. The projections include jaws to engage the mating hammers.[1] Pile gates lock the base of the pile in the leads, and they hold the pile rigidly parallel to the lea d column. In most cas es the pile gate eliminates the need for a separate pile template or false work. Figure 2.13a-b-c-d 2.4 Positioning Equipment Positioning equipment mainly include piling frames, trestle guides, and vertical lea d sections. These positioning equi pment are classif ied int o these three types due to their usage. While a wide variety o f positioning equipm ent was used in the past, today some of them would not be considered efficient and are not used.


20 2.4.1 Piling Frames The essential part of piling frames are piling leads, which are stiff members of solid, channel, box, or tubular section held by a lattice or tubular mast that is i n turn supported at the base by a movable carriage and at the upper level by backstays. The latter can b e adjusted in le ngth b y a truly vertical position or be raked forwards, backwards, and sideways. Piling leads guide t he pile to it s correct alignment fr om the stage of its fi rst pitching in position to its final penetra tion. It also carries the h ammer and maintai ns it in position co-axially with the pile Whereas p i ling frames are mounted on elevated staging, ex tensio n leads can be bolted to the bottom of the main lead in order to permit piles to be driven below the level of the base frame. The Piling Winch is mou nted on the base fram e, and could be double or m ultiple drums w hich can handle hamm er and lifting pile. Thi s piling winch can carry out the d uties of operating the traveling, slewing and raking gear on the rig. A different type of pil ing frame is German manufactured Menck tubular fra mes, which have a single box section lead and frames made in five sizes with useful hei ght s ranging from 57 ft ( 17.5m) to 115 ft (35m). These piling leads can move forward and backward and sideways and carry 20 tons hammer with ram. Other piling frames include German Delmag Piling fram e tubular and latticed tub ular frames which have sizes that range between (25ft) 7.5m to 18.4m(60ft) and Swedish Akermanns M14-5P, which is 21m (69ft) high and operates a five-ton drop hammer. Its lead can be adjusted by hydraulic rams to forward and backward rakes of 26 and 45 degrees respectively. The German Menck and Delmag piling fram es are lighter and easy to erect.


21 Piling f ra mes can be designed for specific purposes. For example, the American–designed “moon beam” frame is used for driving raking piles for jetty structure s. A flat angle (1in 2.4 ) is possible and a sideways rake prevents the piling fr ame fro m becoming locked to the pile on a ris ing tide, which can happen when drivin g from a pontoonmounted rig with only a backward or forward rake. [1] 2.4.2 Trestle Guides A trestle guide functions as a lead. A pile is held at two points known as gates, and the trestle is moved from one group to another group by a crane.. Trestle gui des can be used in conjunction with pilin g frames. The pile, w hich is placed and held by a crane, is driven to penetration level. T he trestle’s leg keeps the pi le in the alignment. Tr estle guides are useful if there are rows of driven piles at close centers simultaneously; ther efore, these trestle guides are mostly used for wall foundations 2.4.3 Vertical Leads The primary purpose of pile driving leads is to h o ld the pile in position and the hammer and pile in axial alignm ent. Leads should be f itted with extensions to permit, when necessary, the hammer to operate below the bottom of the leaders. Pile driving leads should be sufficientl y rigid and fixed to hol d the pile firmly in its required position and in axial alignment with t he pile-driving hamm er. Lightweight or f ree-sw inging leads can permit the pile to drift off locat ion and out of the requi red alignment. Eccen tric hammer blows could also result in prod ucing dri ving str esses higher than the yie ld or ultimate strength of the pile material with it resulting in bending, spelling or braking. [2]


22 The usual practice of crane-supported ve rtical leads is to link the leaders to the he ad of the crane jib and to contr ol their vert ical or ba ckward or forward rake by means of adjustable stays near the foot of the leads. The average height of leads are 19.0m(62 ft) and 21.9m (72 ft) and carry approximately 3 tons mass of hammer.[1] Vertical leads are designed and manuf actured by different c ompanies because the ir usage can be different and d ifferent co untries seem to prefer certain types of leads. For instance, U-Type lead sections ar e used in the United States of Am erica more than Europe and Canada, and Berming hammer designed leads which have “II”,”C”, and “Box” sections are considered European type leads.[6] The classifications wh ich are done by manufacture rs according to section design are listed below. The first group is the Berminghammer New Designed “C” Section Leads. As a “Vertical Travel Lead,” a new lead column had been designed and produced b y this company. The “C-12” and “C15” leads, which are enhanc ed in strength, are new d esigned lead columns that are consi dered lighter but with si mil a r construction to the “C-18” lead. The “C-12” is also a new designed section compared with L-12A lead, which is the older version. The “C-15” is simil ar in weight to the H-12 and lighter t han “H-12A.”At the same time, it is stronger tha n either of older sections. Als o this new section is con sidered to replace the H-type lead section, and properties of these sections are included in the Appendix A3. The second group is the Berminghammer New Designed “II” Section Leads. The new Vertical Travel Lead “II-21” and “II-22” sections were designed to accommodate long, heavy piles and heavy hammers, and the properties of these sections are below. Appendix A3.


23 The third group is the Berm inghammer New De signed “Box 26” Sectio n Leads. These Vertical Travel Leads are very simi lar wi th U-Type leads, which are designed by HPSI, Pile Equipment, and Pileco. The 26 inches s ection incorporates a c ontinuous rear tr ack to provide for raising and lowering of the lead column through the upper slide on the front end of the kicker. This rear track does not f unction as an integral pa rt of the lead structural design. The lower section of a l ead incorporates a contin uous rear track on the lead center line for engagement of t he lower slide safety st op. In designing leads, the stiffness of join ts and the lateral rigidity are made to withstand side batter applications and lead swivel rotation is very important, and needs to be meticulously conside red. The Bermingham mer lead includes a hammer/auger trac k on the front face, a s lide track on the rear face an d man –access ladder rungs on both sid es with a safety belt fastening points throughout the length. Other lead manufacturer companies especially HPSI, Ple Equi pment, Vulcan have their own U-type which is very similar to Box-Type o f Berminghamme r. The sizes are quite similar, but each lead is their own design and there are som e differences in sizes. Also all these leads are available in ran ge of sizes to fit all standar d pile hammers. Strength, lightweight o f tubu lar steel construction, b olt connection strength and quality of weldin g are all significant factors in the manufacturing o f leads. Leads are desig ned in varying lengths from 10` to 30`. Some types of leads are U, box, and C series. An exam ple of a vertical lead from the C-series, specifically C-15 is the Vertical Travel Lead, designed by Berminghammer. The purpose of designing this lead i s to multiply the functions of the le ad and make pile driving more eff icient without decreasin g the strength capacity o f the ham mer The functions of the V TL by Bermingham mer can be summar ized as follows:


24 aThe entire lead column can be independently raised an d lowered in any of batter position. bThe leads can be raised before driving a p ile, wh ich allows for the driving of longer piles cThe leads allows the hammer to be guided to cut-off elevation regardless of boom angle. dLeads can be lifted cl ear of obstructions. eThe leads allow the cra ne to sit on the ground hi gher than pile area. fPile hammers may be mounted by f irst rising and then lowe ring the lead track in to th e hammer guides, eliminating the need to use a hole in the ground or to unbolt the hammer guides.”[4] We can classify crane-sup ported vertical leads into three main groups acco rding to their usage and design: a. Caisson type : These typ es are used for installing c oncrete cylinder piles an d steel pi pe piles in marine construction. Various models are available for pile sizes up to 48’’ ( inches) diameter. For pile siz es over 48” diameter (d ia), spec ial adaptors can be manufactured, or for specific large diameter, a new lead can be manufactured.[5] b. Truss Type Lead System s: M ost o f the contractors prefer this type because of easier service access to t he hammer and it is ea sier to adapt for sheet p iling applications. c. U, Box, or C-Series Type Lead Systems: These types of leads can be used as free swinging leads, fixed -extended or as vertical t ravel leads. The characteristics of free swing lead systems Figure 2.12 include: aThey are useable with every crane of the right lifting capacity


25 bThey have same lead se gments like fixed system except top and bottom section. cThey can also support ed with hydraulic spott ers dThey are very adaptable to dif ferent elevations and b atter piles, but takes much longer to position. The characteristics of the fixed-extended Figure 2.13 lead system include: a. They are attachable to m ost of cra nes b y using a boom point–connector to the existing crane bo om tie or so called h ammer head attached t o the crane boom. b. They are designed to fit other model of hammers. c. They can be interchan geable in order to perm it various length comb inations. d. They can be position ed faster, and are well s uited to level job site. T her efore, these leads are utilized with pin connectors for quick field assembly. However each company has a different pin connection design for their own lead. Vertical Travel Lead (VTL ) is combined the advantageous of fixed leads, fast and accurate positioning, with the ability to adjust the height of the lead base up or down. The VTL is connected to the boom by sliding connection which allows the lead to be elevated or lowered. The structural column of the VTL resist bending in forward, aft, and s ide batter positions. The hydraulic spotter is very rugged and transmit torque to the body of the crane rather than boom.


26 Figure 2.1 Concrete Pi les Figure 2.2 Post-Tensi oned Piles


27 Figure 2.3 Steel Pipes Figure 2.4 HP Steel Pil es


28 Figure 2.5 Sheet Piles Figure 2.6 Diesel Hydr aulic


29 Figure 2.7 Vibratory H ammers Figure 2.8 Mc Air Ham mer


30 Figure 2.9 Hydraulic H ammer Figure 2.10 Driving ca ps and Helmets


31 Figure 2.11 Pile Gate


32 Chapter 3 Experimental Program 3.1 Overview This chapter discusses the experimental setup used to evaluate the performance of a box-type lead section manuf a ctured by Bermingham mer Foundation Equi pment in Hamilton and Ontario. The intent of the experiment was to determine th e adequacy of a new connection that utilizes both perimeter bolts and a centroidal solid steel spigot. Therein, the shear stresses are intend ed to be carried by th e spig ot and bending stresses by a combina tion of the bolt group moment of inertia and the spigot bending strength. The determination of the balance of these two components and t heir relati ve contribu tions are the focus of this test program. The holes in the lead have m inor resistance to th e effects of bending. These hol es inside of the lead (in the channel sect ions) are there to reduce t he weight (They are prob ably no more than the weight of weld s.) Coincidently, they are very handy for the installation of the instrumentation. The holes in the face, which faces the crane supporting the lead, are for the safety stop on the kick er. If the kicker is raise d too high, the forc e on it from the le ad may want to push the kicker up the lead. In this condition a spring loaded safety stop will deploy into one of the holes in the back face of the lead.


33 The test specimen was fabricated and shipped to the University of South Florida by the manuf acturer on M ay 22, 2002. The lead s ection, denoted as a m odel C15, was fabricated from two C15 rolled steel sections on which two, 20” wide, 5/ 16” thick plates were welded to form a box -type section. The total lead length was 30ft long, comprised of two 15ft pieces connected at the center point with t he new connection type Figure 3.1 and 3.2 shows the details of the connection. Each hollow box section was strengthened with five plates that were laterally orien ted and welded to provide additional stiffness. On each side of the lead (in the C15 secti ons) and one of the two plate faces (Figure 3.3), holes were cut not only to reduce weight but also, to provide lad der-type steps to aide in pile hammer access in the field. The fourth face was left uncut to provide the surface on which a hammer cou ld slide. 3.2 Test Setup As the axial capacity of the connection was not of any serious concern, a four-point bending loading scheme was devised that would concentrate the bending stress in the region adjacent to the connection. The test specimen weighed 3330 lbs and required the use of tractors and an overhead crane to facilitate its placement under the loading frame. Figures 3.4 and 3.5 show the specimen be ing offload ed from the tractor-trailer, loaded into the laboratory, and situate d under the loading fra me. Installation on the lead section: As th e hammer was mov ing up and down, the ho les on the lead helped th e cable installa tion and proper move me nt of t he hammer. In this experiment, the displacement of c onnection, which is in t he middle of th e lead, was monitored.


34 The connection was designed i n three parts. These are t wo hollow lead section s, connection parts which are a cylindrical section, and bolts and connection accessories. Therefore, the two ho ll ow lead sections had been connected together by bolts and connection accessories and a solid cylindrical section was put into the hollow lead sections. The connection was the most important part of this lead section. When the the four point bend ing load was applied (60in from the center connection symmetrically) to the lead section ( Figure 3.6 ), deformation was observed. Figure 3.7 and 3.8 A load displacement curve up to 140,000lb (total load) linear deformation was observed. After this point, nonlinear defo rmation was observed until 175,000 lb (total l oad). However, the connection of lead sec tion yielded after 140, 000 lb. After the load h ad been re move d from the section, permanent deform ation was observed whi ch was 2.5 in the middle of the lead section (connectio n). Figure 3.9 After the test had been c ompleted, there were difficulties in the removal of the bolts and nuts, which are on the tension side. Deformation was not observed on two sides and their top bolts. There w as plastic deformatio n on the spigot, which i s locate d in the leads. This deformation wa s symmetrically arou nd 1/16 in on both ends. However the face of the lead sections had no plastic deformation due to slight yielding. In the experiment, 48 “C EA-06-125UR-120” ty pe rosette type st rain gages, six “STB AD808FB” blocks, 3 LVDT, and as data acqui sitio n system Megadac Exp o 114AC were used, and the experiment was completed in the structural laboratory at the University of South Florida.


35 3.3 Instrumentation The lead consists of two main pieces and connection parts. First, the cyl indric al section, which is an essential con nection part was inserte d into the half lead and affixed with a screw; then the other hal f of the lead was attach ed on it and then connected with the other half of lead with Hex HD1/2, bolts. Four bolts were used for bottom and top, two for each sides, so a total of 12 bolts were used for connection with their accessories. This connection is shown in the figure 3.10 and 3.11 The l ead sat on two steel rollers (o nly Y direction was rest ricted, X and Mz were free) and each roller was locat ed 25 ins from each end of the lead. Figure 3.12 On the spot where the roller was located, there was a vertical plate of le ad, which was welded i nside to the lead to strengthen the stiff ness of the lead. Strain gages (CEA-06-125UR -120) were then installed on each side in 12 spots on the lead; four spots were on the solid cylindrical section and connected cables to six “ STB AD808FB” block s, then these blocks were connected t o the computer through megadac. 3.3.1 Strain Gages Strain Gage S pecifications CEA gages are widely used in experimental stress a nal yses and in this experiment the CEA-06-125UR-120 w as used to measure the s train values. Resis tance i n ohms at 24 deg C is 120.0+0.4% or 120.0-0.4%, and gage factor at 24 C is 2.075+1.0% or 2.075-1.0%. Transverse sensitivity was at 24 C and 50%H. These gage s were supplied with fu lly encapsulated grid and exposed copper-coated integral solder tabs. Ope rating te mperature range was from –100 to 350 F (-75 to 175 C), and strain limits w ere approximate ly 5%


36 for ga ge length 1/8 in (3.2mm ) and larger; approxim ately 3% for gage length s. Their exposed area was 0.08x0.06 in (2.0x1.5 mm) and 45 single plane rosettes. The definition of CE A 06 125 UR 120 strain gage that used in this experiment. [13] CE: Thin, flexible gages with cast polya mide backing and encapsulation featuri ng large, rugged, copper coated solder tab s. This construction pr ovides optimum capability for direct lead wire attachment. [Carrier Matrix (Backing)] A: Constant alloy in self-temperature-compensated form. (Foil Alloy)06: Self-Temperature-Compensation. The S-T-C number is the approximate the rmal expansion coefficient in PPM/ F of the structural material on which the gage is to be used. 125: Active Gage Length in Mils (thousandths of an inch) UR: Grid and Tab Geom etry 120: Resistance i n Ohms Strain Gage instrumentation There were 12 spots on the lead and 4 spots on the cylindrical section for strain gage installation. Therefore, a total of 1 6 rosette strain gages we re used for this measu rement ( 48 gages). On one half of the lead, strain gages were instal led in the middle to four s ides (top, bottom, right side, left side), in the quarter four side s, and at the end four si des again as i n Figure 3 .13 On the cylindrical solid steel spigot, which was inserted into the lead to strengthen the connection, four r osette strain gages were installed on four sides bottom, top, right side and left side. Figure 3.14 Also, each of the strain gages (rosette gages) consisted of thr ee gages, whic h were located X, Y and diagonal directions. In the general case; maximum and minimum normal stresses, and t he principle stress directions were not known.


37 The angle defines the ori entation of the princip le planes, that is, the pl ane on which principal stress acts. The angles to the planes of zero shear stress are the same as the angles to the principal planes. Th erefore, three unknow ns s 1, s 2 and principle angle 1 must be determ ined in order to specify the state of stress at the point. Thre e element rosette strain gages were u sed in the experiment t o obtain the required pri nciple strain data. How ever, three strain measurement s were suffic ient to determine the state of strain at a point on the free surface, which was de monstrated by consid ering the thre e ga ges aligned with axes longitudinal, lateral and diagonal. Using the equation of strain transformation:p A = p xxcos 2 A+ p yysin 2 A+ ( xysin 2 Acos 2 A p B = p xxcos 2 B+ p yysin 2 B+ ( xysin 2 Bcos 2 B p C = p xxcos 2 C+ p yysin 2 C+ ( xysin 2 Ccos 2 C The Cartesian components of strain p xx, p yy, and J xy were determined by solving the equations above if p A p B, and p C were known like in this s ituation (t he se data were supplied from the experiment). The principal strains p 1, and p 2 and principal direction 1 were then determin ed from: m 1=1/2( p xx + p yy)+ % [( p xx + p yy)+ ( xy] and m 2=1/2( p xx + p yy)- % [( p xx + p yy)+ ( xy] 1=1/2tan [ ( xy/( p xx – p yy)], where 1is the angle be tween the principal dire ction for m 1 and the x-axis. The three rec tangular rosette gages were designed with 2 A=0, 2 B=45, and 2 C=90 Therefore; p A = p xx p B =1/2( p xx+ p yy+ ( xy) from this equatio n; 2 p Bp xxp yy= ( xy and p C = p yy When p A, p B, and p C were substituted the p rinciple s train m 1, m 2, and principal angle 2 1 were obtained in the terms of p A, p B, and p C from the experim ental test data.


38 m 1=1/2( p A + p C)+ % [( p A p C) + (2 p Bp Ap C) ] m 2=1/2( p A + p C)- % [( p A p C) + (2 p Bp Ap C) ] 1=1/2tan (2 p Bp Ap C )/( p A p C) 0< 1<90 when p B >1/2( p A + p C) -90< 1<0 when p B <1/2( p A + p C) 1=0 when p A> p C, and p A= m 1 1=90 when p A< p C, and p A= m 2 Finally, the principal stresses w ere determ ined in t erms of A, B, and C by the substitutions into the e quations above. Strain gage installation can be done in three main steps. These are: first, surfa c e preparation; second, strain gage bonding; and third, soldering. The purpose of surface preparation was to develop chemically and physically clean and smooth surface for bonding. The first operation was to clean up the spot w here strain gages would be bonded. Therefore, the first operation was de-greasing. CSM-1 de-greaser as a solvent was used with the clean gauze sponge to clean the entire lead. Then the surface, where the strain gages were, were abraded to remove the paint and oxides and to develop the surface texture suitable for bonding with 220-grit silicon-carbon paper. Abradi ng wa s started with a grinder and a s ande r, and M-prep Conditioner A was placed in the gaging areas. A conditioner was adde d during the lapping pro cess to keep the abrading surface wet. Afterwards, the surface was polished and was wiped dry with a clean gauze sponge and was handled carefully so as not to drag contaminants back to the gaging area. Then, using the 320-grit siliconcarbide papers the abrading was repeated. After the abrading was done, the desired locations were marked with a ball-point pen or a tapered brass rod was us ed. After marking, the next step, “Conditi oner A” was a pplied repeatedly and th e surface scrubbed with cotton-tipped applicat ors until t he clean tip was no longer discolored by scrubbing.


39 When the surface was proper ly cleaned, the clean are a was wiped with a single slow stroke of a gauze sponge. The stroke started in the middle of the cleaned area and wiped to one side, and the second stroke started from middle to the opposite side. For each stroke, a new gauze w as used and then the used one was thrown away. T he cleaned area was caref ull y protected against any contamin ants, which could com e from the dragging w ith the sponge. In order to provide optimum alkalinity for Micro-Me asurements, strain gage adhesives and the cleaned surfaces had to be neutralized; therefore, the neutralizing was done by applying M-Prep Neutr alizer 5 A, and scrubbing the su rface with a clean cotto n-tipped applicator. During this operation the surface was kept wet with Neu tralizer 5A, the surfac e was then dried with a clean gauze sponge using the same procedure mentioned previ ously (wipi ng from the middle to one side then to the oppo site side with a single slo w stroke). The surface was clean and ready for gage bonding. Technically, this gage installation should be done within 45 minutes. Electrical resistance strain gages are capable of making accurate and sensitive indications of strains on the surface of the steel, and their performance depend upo n the bond existing between them and the test part. Because of their sensit ivity, strain gages were carefully removed from its ac etate envelope by grasping the edge of the gages’ backing with tweezers and placing them on a chemically cleaned glass plate with the bonding side of the gage facing downward, and one end was anchored to t he glass plate behind the gage and terminals by M-Line PCT –2A cell ophane tape. The next s tep was to carefully pick up the gage and terminals and lift the tape at 30 45 angle until the tapes came free with the gage and terminal which were s till attached. The strain gage was ready for placement; theref ore, the gage tape assembly wa s carefully positioned The tape was held at a shallow angle; the


40 align was wiped; the tape was again lifted at a shallow angle until the a ssembly was free of the specimen and was repo sitioned; then the assem bly was again wiped at a shallow angle In order to apply adhesive the end o f the tape was lifted op posite the soldier tabs at a shallow angle until the gage and terminal was freed from the specimen. M-bond 200 Catalyst was sparingly applied in a thin uniform coat and brushe d over th e entire gage surface. The catalyst was then allowed to dry for at least one minute. The gage/tape assembly was held in a fixed position; one or two drops of M-Bond 200 was applied at the junction of the tape. The spe cimen surface was ab out 0.5in (13mm) outside the actual gage installation area. The tape/gage assembly was immediately rotated to approximately a 30 angle to bridge over the instal lation area. Then the tap e was slightly held taut, and beginning from the tab end of the gage, a single wipin g stroke was slowly made over the g age back down over the alignment marks on the specimen. All these steps for adhe sion were done in five seconds; otherwise the adhesive material wou ld have cured after enco untering th e air and adhesion would not work efficiently. As soon as these steps were completed, the gauze was discarded and thumb pressure was applied to the gage. This pressure was applied for approximately one m inute. It was allowed to stay for two more minut es to create a better bond. The tape was removed by pulling the tape back directly over itself; it was peeled very slowly and steadily off the surface. After the soldering iron reached the operating temperatur e, the tip was cleaned with a gauze sponge and tinned with fresh sold er. The gage tabs were ti nned with the soldering. A small amount of so lder was melted on the tip of th e soldering iron; then a r osin-core solder wire was laid across the gage tab and for one second firmly applied the iro n tip; finally, both the solder and tip were simultaneously lifted. Ev ent ually, a bright shinny s older was


41 deposited on the tab. If no solder was deposited, the soldering procedure was repeated. The three-conductor lead–in wires were first separa ted into individual lead s of in (20mm), then 1/2in (13mm) of insulati on of the wire was strip ped away by using the solde ring tips to melt the i nsulation on both sides of each end of the wire s. It was advised to not use a knife o r other blade. When the mai n lead wir e wa s stranded and termina l strips were used, it was convenient to cut all strands except o ne to fit the size of the copper pad. The longer strand then was then used as jump er wire. This method m ade soldering easier, bu t it was found this procedure was unnecessary if the lead wires were bonded directly to the solder tabs on CEASeries Strain gages. Each wire was cut by diagonal wire cutters and left 1/8in (3mm) of exposed, tinned wire. The lead in wires were tacked to the specimen with drafting tape so that the tinned end of the wi re was spring–loaded an d in contact with the solder bead. The solder connection was comp leted as before, for example, by applying the solder and iron tip for one second and remov ing them simultaneo usly. A rosin solvent w as applied to the solder joints. The protective coating (M-Coat A) was applied over the entire gage and terminal for long term, and it was applied to 1/8in (3mm) of lead wire insulation. Test Set up The experiment was run in the structure labo ratory of University of South Florida. In the structure laboratory the frame, which had been previously installed, was functioning as support system to apply force through hydraulic jack s on to the lead shown in Figure 3.15. In order to apply the nodal load, two hydraulic jacks were located 60 inches from the center (connection of two pieces) of the le ad symmetrically, a nd two steel p l ates (20x20) were located beneath the j ack to distribute the nod al load onto the lead whe re the steel plates faced. Figure 3.16. Therefore, these jacks were installed with the help of the other fr ame


42 system to the main fr ame. When the jacks st arted to push upwar ds, the fixed big fr ame reflected the same load back to th e specific location on th e lead through the hydra ulic jacks. Between the main big frame and the hydraulic jacks, the Load Cell was placed to mea sure the load inc rements during the exp eriment period. Also at the top of the Load C ell, on e more steel plate was placed to give a straight surface f or the load cell to get the read ings corrected as shown in Figu re 3.17. On tw o sides of the center, hy draulic jacks and load c ells were installed as ment ioned above. Theoretic ally, the two jacks would hav e synchronized while incrementin g the load on the le ad so that some idea about the capacity of this lead in tension would be known. The Load cell no:1 was connected to channel 0 and other Load cell no:2 was connected to the cha nnel 1 in Megadac, whic h is a data acquisition system. The lead was placed on the roller p in support, which restr icted the movement on Y direction under the frame along the west-east side. Figure 3.18 The steel roller was placed on the concrete bloc k, which was then pl aced under the main big frame to support the lead. There was no horizontal load or it might have slid; the load was applied jus t to the vertical, so there was no reason to restrict either X or Z directions. There were three LVDTs locat ed under the lead to me asure the displacemen t, specifically under the connection due to connection failure. One LVDT was placed u nder the connection on the center; the other two were placed 60 inches from the cente r symmetrically. These were also c onnected to Megadac by separate numbered cables, and each channel number was c hosen according to these cable numbers. For example, the west side of LVDT was connect ed to chan nel 2 in Megadac; the mi ddle one was connected to channel 3; and the east one was connected to channel 4.


43 The 16 rosette type strain gages were instal led on the lead section throu gh numbered and different colored wires as it is shown Figure 3.19. The first set of strain gages (four rosette gages) were placed 12 inches f rom the middle of the lead and were installed on four sides (up, down, right and left sides) of the cylindrical solid steel spigot. The second set of strain gages (four rosette gages) was placed 36 inches from the middle and the third set (four rosette gages) was placed 95 inches from the middle of the lead. Therefore, th e principal stresses on three sections on the lead and one section on the solid steel spigot were measured through the strain data at end of the test. Also these gages were placed on the four sides of the lead, and all the gages were num bered for strain reading s during the experimen t. Which strain valu e belongs to which pla ce was monitored to calculate maximum principal stress and other stresses that oc curred on the lead or spigot side s. All these strain gages were connected to Megadac with the prev iously numbered ca b les. The cables, which were different colors to distinguish th em from ea ch other were connected to blocks, had 8 channels sockets to connect them through Megadac, and th e blocks h ad a quarter bridge configuration. Therefore, all eight channels were conn ected to Megadac through circuit blocks which are called STB 808FB-1. There were two major func tions of th ese circuit blocks: A) To provide a fast and friendly interface from the bare wire leads of quart er, half or full bridge strain gag es to the AD 808FB-1 an alog input cards. B) To provide bridge completion resistors for quarter and half bridge strain gages. These STB`s were either 120 S (STB 808FB/120) or 350 S (STB 80 8FB/350), and provided the interfacing and bridge completion for eight channels of strain gages.


44 Also, there were five screw te rminals per channel labeled from left to right V, +, -, R, G, and three jumpers to set up a half quarter, or full bridge configuration. For th e first channel in the upper left corner of the STB (recognized as channel 0 in Optim terminology) were J01, J02, J03. For example, for J01: J was jumper, 0 w as the channel number, and 1 was the jumper number o f the channel It is listed as the strain ga ges connec tion to the Magadec as illustrated on figure 3.20 L: Longitudinal D: Dia gonal T: Transverse (La teral) STB Terminal Block I (1-8) was connected to channels from 40 to 47.STB Terminal Block Set II (9-16) was connected to channels from 48 to 55.STB Terminal Block Set III (17-24) was connected to channels from 56 to 63. STB Terminal Block Set IV (25-32) was connected to channels from 64 to 71. STB Terminal Block Set V (33-40) was connected to channels from 72 to 79.STB Terminal Block Set VI (41-48) was connected to channels from 80 to 87. All cables from strain gage to blocks were passed through the lead holes in the lead, and came out from end o f the lead to connect to t he blo cks. For all four gages, the connection of one section (four si des) was tied to each other to make the connectio n easier and more understandable. 3.3.2 LVDT The Linear Variable Differential Transformer (LVDT), which i s a n electromechanical device, is commonl y used as a variable-indu ctance transducer to measu re displa cement. It is designed to produce an AC voltage output proportional to the relative displacement of the t ransformer and the ar mature (Iron core).


45 In the experiment, the LSC 4” Model E-314 Long year LVDT`s (sensors#121, 122, 123) were used. It had a 10 volt exc itation and the sensi tivity wa s S=51.809mv/4.027 in/10volts. Principle of Operation After the AC excitation signal was applied to th e primary coil, voltag es were induced in the two secondary coils The magnetic core inside the coil winding assembly provided the magnetic flux path which linked the primary and seco ndary coi ls. Secondary coils wer e connected to a series opposing in the center or null position, because the two voltages were of opposite polarity. Since the output voltages were equal and o pposite in polarity, the outp ut voltage became zero; also, the null position of LVDT became very stable and repeatable. After the magnetic core was displaced from the null position, an electromagnetic imbalance occurred, and this imb alance gener ated a differential AC out put voltage across the secondary coils, wh ich was linearly proport ional to the direction and magnitude of the displacement. When the magnetic core was moved from the nu ll pos ition, the induced volta ge in the secondary coils, which the core moved toward, increased while the induced voltage in the opposite secondary coil decreased. Construction The typical LVDT consists of a movable core of magnetic material and three coils, which are t he primar y coil and the other two s econdary coils, comp rising the static transformer.


46 Transformer The basic transforme r formula states that t he voltage is proportion al to the top of the number of coil windi ngs, which is the backb one of the LVDT. The formula: Vout/Vin=Nout/Nin where N was the numbe r of coil windings and V was the voltage read. When the iron slid through the transformer, a certain number of coil windings were aff ected by the proximity of th e sliding core and thus g enerated a unique voltag e output. Open Wiring LVDT Most LVDT`s are wired as open wiring. The output voltage was proportional to iron core displacement when th e core slid through th e tra nsformer. The form ula was: D=M*Vout, where D was the displacement of the iron core with respect to the transformer, and M was the sensitivity of the transformer, which was sloped of the displacement-voltage.. Ratiometric Wiring LVDT The other type of wiring was ratiometric wiring.For this wiring the displac e ment formula was D =M*(Va-Vb)/(Va+Vb), and there were many advantages as stated below: Relative low cost due to its popularity. Solid and robust, capable of working in e wide variety of enviro nments. No friction r esistance, since the iron core does n ot contact the transform er coils, resulting in an infinite (very long) service life High signal to noise rati o and low output impe dance and negligible hy steresis. Infinitesimal resolution (theor etically). In reality, displacement resolu tion was limite d by the resolution of the amplifiers and volta ge meters used to proce ss the output signal.


47 Short response time, only limited by the inertia of the iron core and the rise time of the amplifiers. No permanent damage to the LVDT if measurem ents exceeded the desig ned range. [16] 3.3.3 Hydraulic Jacks In order to apply nodal load, two hydraulic jac ks, which were 10 tons c apacity (each), and Enerpac, model 5013 were used. These cy lindric al lightweight hydrauli c jacks were very practical and easy to carry and position since aluminum is a non-corrosive material and can be used in many causti c environments. Also it was made of 7075T -6 alloys, with a complete hard coat treatment, which pro vided a strength that riv als the strength of steel. The composite bearing, which covered the cylinder prevents metal-to-metal contact, reduces the side load issue and increases the life. Removable steel base plate and hardened steel sadd le resisted wear caused by use on co ncrete and other abrasiv e surfaces. Capacity range of hydraulic jacks were up to 150 tons; however, in the experiment, a 10 ton capacity one was used. Also, full stroke range was from 2 to 10 inch. There were four v ersions, which were S/ A sol id, hollow and lock nut and D/ solid –Enerpac hydraul ic jacks, which were ver y extensive Aluminum line in the industry. [17] 3.3.4 Data Acquisiti on System (Megadac) Data Acquisition Systems accepts input from a large number of transducers an d automatically process the data. Even though they are similar to Data Loggin g systems they are muc h faster than Data Logging systems (sample rates from 20,000 to 250,000 p e r second), and the on-board microcomputer, m emory capacity, and s peed of data-acquisition system incomparably more than data-logging syste ms. Sampling rates can be increased by


48 replacing DVM with high speed, s uccessive approxima tion, and analog to digi tal converters. The converters utilize sam ples and hold amplif iers that sample and ho ld the input value fixed during the conversion period. For example, for hig h-speed operations (25 0kHz) the flash type A/D converters can be u s ed. There are some opt ional components in a utomatic data acquisition system, and it can be custom design ed. All systems contain six ba sic subsystems, which are the controller, signa l conditioner, the mul tiplexer/amplifier, the analog to digital converter (ADC), the storage or memory unit, and the read out devices. The controller is a microprocessor that serves as the interface between the operator and the data acquisition sys tem. The operator ent ers the directions to the controller through the front panel keypad. A liquid crystal display (LCD) supplies readout of the syste m operating parameters and select readings of the quantities being measured. There are some parameters that affect programming the controller and data flow. These are the sampling rate, the sequence of channe ls to be monitored, the signal levels to trigger and t o stop recording, the time limits for th e same purpose, and th e activatio n limits for supervisory alarms. Also, the controller dir ects the flow of data collected in the random access memory. The data storing in the RAM buff er can be held for one cycle, erased, or transferred to a permanent storage medium suc h as hard disc or, onto high c apacity systems, an o ptical disc. The si gnal conditioner consists of power supply, the Wheatstone bridges, and terminals used to connect the output from a large number of bridges to the multiplexer. The bridges are contained on the plu g in a circuit board, whi ch can be modifie d by adding or deleti ng fi xed resistors to provide for quarter, half, or f ull bridge configurati ons. In this experiment three wire quarter bridge configuration was applied. The single wire from the


49 strain gage was connected to the (+) screw terminal for the channel, one of two wires on the other side of the strain gage was attached to the (-) screw terminal while the third lead was inserted to the R terminal. J01 and J02 were installed. J03 was installed in the 2-3 position as shown in Jumpers J+S1 and J-S2 were installed. Commonly, one single power supp ly was u sed, and it was highly regulated, by a constant current supply th at can be adjusted to provide about 4 mA to the bridge. There were two parts in the multip lexer portion of the sig nal conditioner scanner subassembly: The two output leads were connected to a bank of switches and the cable shield from each bridge to the differen tial amplifier. Nowa days, solid-state switching devices are used. Second, the circuits that control the switching sequence s were prog rammed in the controller. The low voltage signal from the bridge was switched through the multiplex er to the differential amplifier. The signa l was amp lified to be consistent w ith the full-scale voltage of the ADC. There are two types of ADC, which are the dual slope integrating type and successive approximation type. The dual integrating ADC is slow if 1K samples per second for low performance data logging system but the successive appro ximation ADC are m ore advanced acquisition systems due to its speed, which range from 20,00 0 to 25 0,000 samples per second. The data from the ADCs a re output from the interface unit on a parallel wired data bus and stored in RAM in first in fi rst out basis. T he data can be downloaded from RAM to permanent storage medium suc h as a hard disk. Data can be stored high on an optical disk for high capacity systems but not in this case. The instructions and addres ses are transferred


50 from the controller by the bus carriers, and it provides for the flow of the data and the organization of the memory devi ces. In digital forma t disks provide the inpu t data to an offline computer, which pro cess the data. Therefo re the data can be t ransf erred to spread sheet through software, which is used specifically for those data acquisition systems. ADCs, RAM, multiplexers, and storage devices have been improved; t herefore their capabilities are improved and with the systems capable of 250K samples per second, and a di gital data acquisition system can process several channels of dynamic signals with the capability of an oscillograph.[18] The Megadac product of Op tim Electronics h as ve ry high reliability of da ta acquisition a nd signal-conditioning equipment has been designed to meet demanding applications in th e autom otive, aerospace, and s tructural testing comm unities. With its modular design and programmable i nput and output modu les, Megadac is field expandable to 512 channels and off ers 1 gig aby te of on-board mem ory. Megadac is availabl e in measuring both active and passive transduc ers. Besides that, Megadac 3016 ADC w/808FB1 Cards have been used in this experim ent. 3.4 Running the test As it was mentioned above, all installation was completed on the day before the test. All strain gages were instal led on the lead and hydra ulic jacks were supported from the main frame in the structure laboratory. T wo rollers were placed 25 inches from each end of the lead, and three LVDT w ere located one in the cen ter of the lead and the ot hers 60 inches from the center (connection) Because o f lead w eight (3330lb, 1508.7 6kg), an overhead crane in the structure laboratory was used in the lifting and placing of all heav y equipment.


51 First, in order to check the stre ngth of side direction, th e side of lead was placed up and down on the support. Two hy draulic jacks were pla ced symmetrically 6 0” from center. When the hydraulic j ack’s pr essure of increment s tarted to push the main frame, it automatically reflected back to the lead. The total force of tw o hydraulic jacks were increa sed up to 41500lb, and with the p arallel the displaceme nt incremented to 6.9 8”; however there was no failure and the Load-D isplacement graph is f airly linear, after it wa s unloaded. Therefore, at least this test provided some rough ideas about the bending capacity on sides of the lead. The lead was t hen flipped 90 degr ee on the storage a xis to get the same effect on the connection when it was held by a crane and the hammer was going up and d own. This side was more critical due to the bending of lead and connection. While th e hammer was moving up and do wn the same side becam e more cr itica l. This experiment focused on the up and down side (according to crane hold, front and b a ck). There was nothing added to second test, and the same equipment was used again. The Hydraulic jacks pushed the same distance from center (60”), and applied the force gradually through hydraulic jacks. When the tot al load pressure came up to 160,000lb, it was fairly linear, but after 160,000lb, the connection yielded, and when the total load pressure reached 170,000lb, t he displacement was 4.2 9”, and eventually und er the same load pressu re (170,000lb), th e displacement reached 5.86” which in dicat ed the connection definitely had yielded. Therefore, load pressure was decre ased gradually until i t reached to zero. After the load pressure had totally been remov ed from lea d, t here was permanent displacement of 2.52inches.


52 On the bottom side of the lead connection a permanent gap, which is 5/8” remained. Figure 3.21 The connection had yie ld slightly and the defo rmations, which were mentioned as vertical displace ment and ho rizontal opening occurred as a result. Besides the displacement, the stress distribution on lead was checked and the maximum stress occurred on the top and bottom of the solid steel spigot, w hich had also yielded. The bottom tension strain was 2340 : p ; the top compression was 2430 : p ( p y=1586 : p ). The lead was not deformed; the spigot caused failure and d isplacement. The perm anent displacement was 2.5 ” even though in the figure 3.22 it was seen as 2-7/8” be cause the string rope was fixe d from two ends of th e lead, and as it is sh own S upport s were located 25” from the i nside end of the lead. T his means the support loca ti on leads moved upward while the mid dle sections were displacing downward. While separating each part from each lead, the b ottom bolts and nuts w ere punched together; th erefore, these could not be unscrewed by hand tools and had to be cut to remove the parts. The bolts that were placed on the top and tw o sides were unscrewed easily; they did not cause any difficulties due to any tension or comp ression effect. The connection face of the lead was not deformed, as it was expected to be, bu t th e failure was only very slight, There were no distortions observed on the connection face of lead even though it was checked after the e xperiment was completed. Figure 3.23


53 Figure 3.1 Lead Connection Figure 3.2 Spigot and B olts


54 Figure 3.3 Holes on The Lead For Instrumentation Figure 3.4 Placin g Under The Frame


55 Figure 3.6 Loading 60 From The Center Figure 3.5 Placing Lead


56 Figure 3.8 LVDT For Displacement Figure 3.7 LVDT For Middle Displacement


57 Figure 3.10 Connectio n with 12 bolts Figure 3.9 Permanent Displacement


58 Figure 3.11 Bottom Displacement(LVDT) Figure 3.12 Support 25" From End


59 Figure 3.14 Strain Gages on The Spigot Figure 3.13 Strain Gage Locations


60 Figure 3.15 Hydraulic Jacks Figure 3.16 Applying Nodal Load


61 Figure 3.17 Load Cell Figure 3.18 Pin Suppo rt


62 Figure 3.19 Deform ation Under The Load Figure 3.20 STB Layout


63 Figure 3.21 Permane nt Gap Figure 3. 22 Permanent Displacement


64 Figure 3.23 No Distort ion on Face


65 Chapter 4 Experimental Results 4.1 Overview In this chapter, various types of graphical and tabular output from numerous strain gag es will be discussed. Graphics, which were produced showed the response of various gage locations compa red with each other, and criti cal locat ions were discussed. Graphics were produced from the overall structural respons e, for e xample, LoadDispla cement Load-Strain, Load-Principle Stress-Principle Angle, and Data Point Numbers were graphically mentioned and the results were discussed. Prior to calculating the princi ple strain and stre ss 5630 data points from the experiment were evaluated as load-strain readings and 16 rosette gages were placed on four different sections on one part of the lead and the spigot. The first set of rosette gages(G1, G2, G3, G4) were installed at the twelve, three, six and nine o’clo ck positions on the spigot All four o f the gages were central ized as accurately as pos sible. A second set of r osette gages (G5, G6, G7, G8) were place d like the first set of gag es (on four sides of the lead), but one foot from the middle of the total length of the lead. The third set (G9, G10, G11, G12) were installed three feet from the middle of the total length of the lead, the fourth set (G13, G14, G15, G16) were installed eig ht feet from the mi ddle of the lead. This chapter will focus on the analysis and the correlation of the test results in respect to their the location.


66 Also, the raw data and the c alculated values (principle strain and stress) were reflected onto charts and graphic s to make the structu ral behavio r of the lead more easi ly understandable. On the other hand, prio r to the modeling, und erstanding the st ructu ral behaviors are critical in improving the modeling. The modeling was inspired from the analysis of the structural behaviors contained in this section. 4.2 Principle StrainStress-Angle The most efficient way of verifying the reaction of the lead und er the load pressure was to analyze the stress and strain values that result ed from the experim ent. This revealed where the most critical point s were, or which points could have been more flexible or could have been neglected. Therefore, it can be concluded how t his stru cture reacted and what the capacity of the structu re was, or these values c ould assist in designing future le a ds. The raw strain data were used in the calculation to arrive at the maximum pri nciple strains for each spot where the rosette gages were installed. As it was mentioned in Chapter II about the rosette type strain gages, the purpose of the gages were to have the maximum strai n. T he rosette gage consisted of three gages, which were placed longitudinally, diagonally, and transversely (latera l) on the gage. Since there are three directions, in order to find the maximum and minimum strain value s and the principle angle that gives the maximum strain, these calculations were done for each rosette gage (16). T he most critical strain could be the compress ion, tension or shear str ain. Calculation equat ions were mentioned in the previous chapter. ( D ue t o the failure in the connection, the maximum strain reading was fou nd to be on the solid stee l sp ig ot, which was the mai n connection part. The two parts of l ead were not failed in the experiment. However, the spigot


67 was failed and distorted slightly. When the raw data was monitored, G1 t he gages longitudinal showed 2420 g as max strain and G3 the gages longit udinal had -2340 g the highest strain value under 171,000lb of force which also was in the no nlinear ra nge in the experiment. These two gages were located at the twelve and six o’clock positions, and had values, which were expected to be the same. Since the strain difference of the two gages (G1 and G3) were 120 g the gages were not perf ectly centralized in thei r placement. Therefo re, this diff erence occurred. In addition, the tension occurred on top (G1) and compression occurred on the bottom(G3) of the solid spigot. ( Figure 4.5,Figure 4.9 ) In addition, in linear range, the maximum prin ciple strain observed on the longitudinal gages was 1590 g for the G1, and 1530 g for the G2. ( Figure 4.7 ) Under the same pressure of 144,0 00lb, the tw o diagonal gages of spigot which were located G2 (south) diagonal, an d G4 (north) diagonal, indicated the maximum reading as 114 g and 102 g which were very low and not critical in comparison to the G1(up) and the G3(down). As seen on the figure 4.4 and figure 4.8, the principle angle is zero for both the top and bottom gages. The longitudin al strain gage had the hig hest strain value. However, on the side gages, the gage positioned diagonally had the higher strain value and was fairly low when compared with the top and bottom strain v alues, and the principle angle was close to zero. The principle angle was higher than top and bottom angles wh ich were close to 0.1 rad and 0.6 rad when the maximum load was applied. The applied load reached 170,000lb, then reduced back to zero gradually. The second set of rosette strain gages were located one foot from the center of the total length of the lead and did not indicate high strain values. Si nce these gag es (G5, G6,


68 G7, G8 ) are close to the connection, a big portion of stresses were transferred to the connection. In this case, when the maximum total load pressure was applied, the top and bottom maximum strain gages(G5 and G7) whose longitudinal strain gages became 344 g and 425 g which were not considered high values. Also the si de gages (G6 and G8) maximum values were -319 g and -358 g and these values belon ged to diagonal gages. ( Figure 4.15, Figure 4.19) The top principle angle was zero rad; the bottom was 0.3 rad which was ver y close to zero, but for the side gages (G6, G8), the diagonal gage had the higher value, and principle angle was around 0.6 rad. As seen in the graph, ( Figure 4.12, Figure 4.16 ) the top, bottom, and side stra ins were similar and had low values, and the pr inc iple angle was very close to zero. But for side gages angle, the graph ( Figure 4.14, Figure 4.18 ) had fluctuation which was from +0.6 rad to -0.6 rad. T he thir d gag e set were G9,G10,G11, an d G12, which were loca ted three fee t from the center of the two leads. When the longitudinal gage G9 (Figure 4.21) reached 264 g it was under 120,000 lb pressure, then reduced parabolically to 160 g as the load pressure reached170,000 lb. The transverse strain increased fairly linearly under 170,000 lb load pressure and gave 227 g which was still very low in comparison to the spigot top and bottom values However, the bottom gage G11 (Figure 4.25) had -1640 g which was almost eight times more than the top gage value. The longitudina l strain increased linearl y until 170,000lb load pressu re. There was another issue which needs focu sed upon and carefully analyzed. The G7 (Figure 4.17) rosette gage`s longitudin al stra in 424 g was lower than G11 ( Figure 4.25 ) which was 1640 g Both the G7 and G11 we r e loca ted on the bottom. The G7 was very close to the c onnection at around one foot and the G11 was located at three feet. How ever, the G1 1


69 indicated a higher strain value tha n the G7. If the lead wa s monolithic and had no connection, the G7 would have had a higher strain because, in that case, the maximum moment would have occurred in the middle and would have created the maximum stress and strain. However, in this case, there were connections which took a large portion of the strain from the middle. Adding to this is the fact that the G11 was located at the same spot where the load pressure was applied, but on the underside of the lead section. Therefore, the G11 strain became greater than the G7 strain. When the side gages were observed, the strain-load versus graph of the G10 and G12 acted similarl y. Until 140, 000lb load pressure, there were almost no increases, and the strainload remained nearly zero, but after 140,000lb which was nearly the linear range limit for the spigot, the maximum strain increased up to 122 g for th e G10(d iagonal) and 72 g (diagonal) for the G12. ( Figure 4.23, Figure 4.27 ) The principle stresses were calculated as 47 ksi, which was nearly th e yielding stress for the G11 bottom gage under 17 0,000lb load pressure, and the principle angle f or this str ess was considered to be zero. Figure 4.24 On the other hand, the to p gag e G9 gave a n interesti ng curv e similar to the strain, as it was increased to 8 ksi under 12,000lb, and decreased to 5.3 ksi when the loading reached 170,000lb parabolically, and went up to 6.3 in l ast 1 000lb loading. Figure 4.20 The differences betw een the top and bottom gages readings should not have been that high. Even though the stress values were below the yielding point, the gages readin gs indicated the readings were incorrect. Due to the glueing, the weak adhesions between strain gage and the metal lead surface could have created these false readings; therefore, a fter a certain strain level was achieved even when the real strain


70 increased on the lead, the strain ga ge might not have been read correctly Th e principle angle for this stress was near ly zero again, but during the loading time up to 160,000lb, the angle went to 0.2 rad. During the last 10,000lb loading, the angle increased to 0.8 rad, and it still read very close to zero. The side gages also experienced similar stresses. While the G10 indicated 2. ksi, the G1 2 indicated 3.72 ksi, an d both gages had a simil ar curve. The G12, up to 160,000lb load pr essure, the stress was in creased to 1.5 ksi, then suddenly increased and went u p to 3.72 k si. The G10 has 0.8 ksi under 160,000lb and th en it increased to 2 ksi, and the princip le angle was around 0.6 rad even though there w ere fluctuations. The curve and the stress increments were similar in the two side gages (G10, and G12) on the graph. (Figure 4.22, Figure 4.26) The fourth set of gages were G13, G14, G15, and G16, a nd they were located eight feet from the connection which was located in th e center of the tw o lead lengt hs. The top longitudinal gage indicated 260 g and the bottom longitudinal gage indicated -494 g when total load pressure increased up to 170,000lb The si de maximum strain values are 412 g for the G14 ( Diagonal), and 387fo r the G16 (Diagonal) Figure 4.32, Figure 4.36 In general, the fourth set of value s, which were located th e furthest from the middle connection, were lower than the other three sets o f strain gages. The longitudinal botto m strain gages indicated that there was more tension strain than the other side s, but also the two sides’ diagonal strain values were higher than the top longitudinal gages. Ho wev er, since the strain values w ere not considerably high, the strain values were not cr itical. Since, the strain values were low, the stress values were also low.


71 The sides’ maximum principle stresses were 12 ksi, and 13.3 ksi for both the G14 and G16. Figure 4.31, Figure 4.35 Even though the stress v alues were close to each o ther, there were still small dif ferences. B ecause the G14 and G16 strain gages were not pla ced on both parallel sides accu rately; the small diff erences might have be en derived from their misplacement. The principle angle was nearly zero, but again th ere were slight differences between both of the sides. While the G14 was 0.8 rad, the G16 became -0.4 rad. For the G13 top gage, the principle stre ss was calculated as 1 ksi, and for the G15 bott om gage it became 25 ksi. Figure 4.28, Figure 4.33 The principle angle for the G13 decreased during the load incrementation from 0.3 to 0.1 rad. However, th ese were insignificant val ues and were neglected and the principle angle would be considered zero. Stress increments wer e linear, and it was parallel with the lo ad pressu re. Data readings were very clear and the principle angle was stable as 0.7 rad, which varied slightly from zero. It was necessary to sum marize the strain data a ll over the structure to have a better understanding of the reaction of the s tructure under the max imum load. This would give a better idea concerning w hich location was more critical, where a nd for what reason it wa s necessary to have been more practical and more efficient and in which location stresses were negligible and which on es might assist and stim ulate future lead desig n criteria.


72 Table 4.1 Summary of Prominent LoadStrainLocations Group no Gage Orientati on Bottom ( :, ) Top ( :, ) South ( :, ) North ( :, ) Load (lb) G1 Long -2340 2420 70.5 0 170,000 Diag -983 871 160 -135 170,000 Trans 2.4 -678 18.2 -55 170,000 Gage no 7,8,9 1,2,3 4,5,6 10,11,12 G2 Long -425 271 270 -261 170,000 Diag -278 5 -319 -358 170,000 Trans 381 344 -222 76.6 170,000 Gage no 19,20,21 13,14,15 16,17,18 22,23,24 G3 Long -1640 260,160 0 46 170,000 Diag -662 203 122 72 170,000 Trans 504 227 88 44 170,000 Gage no 31,32,33 25,26,27 28,29,30 36,35,34 G4 Long -492 260 22 387 170,000 Diag 168 177 415 8.44 170,000 Trans -195 35 0 0 170,000 Gage no 43,44,45 37,38,39 40,41,42 46,47,48 4.3 Load-Displacement This study focused mainly on the load and the displacement corre lation and understanding the structure behavior a s was mentioned during the loading proc ess because the load displacement cur ve indicates the capacity of the structure, especially the connection which is the most critical part of the structure. However, the displace ment where the load was applied on two sides of the lead was helpful for th e modeling which wil l be explained in Chapter V in detail. From the Load-Displ acement curve, the ela stic range was monito red as it was increased to around 144,000lb of load pressure, and the d isplacements occurred as 2.09 in for the first load point (eas t), 2.99 in for the middle point, and 2.11 in for the second loading point(west). After that point, the Load -Displaceme nt curves slightly began to yield. When the loading reached 165,000lb, the midd le point displacement became 3.89 in; therefore, the


73 nonlinear portion was clearly obs e r ved. When loading in creased incrementally until 170,000lb, the load pressure was ceased. Therefore, displacement was reached at 4.23 in. Additionally, during the load holding period, the m iddle displacement increased from 4.23 in. to 5.87 in. ( Figure 4.2 ) While applying the sa me loading range from 1 44,000lb to 165,000lb, the east loading point displaced from 2.09 in. to 2.69 in., and the west loading point displaced from 2.11 in to 2.72 in. When the load reached 170,000lb, the east loading point displacement was m easured as 2.93 in, and west loading point displacement measured as 2.96 in, then both displacements were increased up to 4.09 in. and 4.13 in. Due to th e parallel loading, the east and we st loading points` displ acements were equal to each other, and the middle displacem ent was deformed more than the other tw o points. Therefore, the permanent displacement in the middle was me asured as 2.48 in. on th e east and the west loading point became 1.71 in. and 1.72 in. ( Figure 4.1, Figure 4.3 ) Yielding occurred onl y on the connection(spigot) after the loading test sp igot and the two connection faces of the lead were measured. Even though deformation on the connection face wa s neither observed nor measured by a sensitiv e straight angle, it was assumed there would be a distortion on the connection face of the lead and no deformation was measured. H owever, t he spigot was deformed, but only v ery sightly The permanent defo rmation was measur ed as 0.125 in vertically after the test was completed. The permanent displacements for the four sides of the spigot and wher e the strain gages were placed is depicted in the sketch (Figure 4.37) The two sides seemed to no t be disto rted, bu t the top end and bottom end (1 and 3) were deformed slightly. Although the connection fail ed, the o ther connection accesso ries were not distorted except for one bolt connection located on the tension side (bottom). All of the


74 bolts, two for each side, four for the top and from three bottom bolts were easily removed. The bottom middle sout h bolt had to be cut loose because the distortion of the thread s would not allow them to work properly. When 144,000lb of load pre ssure was applied, the p rinciple stress was calculated as 46 ksi, which was the yielding limit of steel that is used for the manufacturing of th e steel spigots. The maximum principle strain was 1590 :, Since these va lues were the most critical in the experiment, it was more convenient to consider those for the indication of the linear portion. Therefore, 144,000lb total force, 3.01 in. in the middle displacement, and the maximum moment was calculated as 684 0kip -in. Simply, if it was calculated from F x=M/Sx, the stress would have been 44.12 ksi which was 5% less than the real value. Also, the strain equat ion = F x/E; the strain was calculated as =(6840/29000)*1,000,000= 1409 :, which was 11% less then the real maximum strain value that resulted from the experiment. These values are similar to ea ch other. This data an d the calculations were i n the linear range. From the experimen t -46 ksi, stress was the referenc e parameter, which in dicated the limit of the linear range for the modeling in chapter V. On the other hand, the ma nual calculations men tioned below were not s imilar to the test results, but it gave an idea about the structure’s behavior. The moment of ine rti a calculated was similar to one of Berminghammers’ calculations, but varied slight ly. Also, the manual cal culations resulting were stiffer than the m odeling and the experim ental results. Moment of Inertia of The Lead :


75 Table 4.2 Moment of Inertia Calculations For Ixx Part area(A i) yi Aixyi Aixyi2 Ii=bh3/12 (Ix)I 1 3 0.5 1.5 0.75 0.25 1 2 4.48 0.16 0.7168 0.114688 0.038 0.152688 3 3 0.5 1.5 0.75 0.25 1 4 5.46 7.82 42.6972 333.8921 84.59 418.482104 5 5.46 7.82 42.6972 333.8921 84.59 418.482104 6 3 15.14 45.42 687.6588 0.25 687.9088 7 4.48 15.48 69.3504 1073.544 0.038 1073.58219 8 3 15.14 45.42 687.6588 0.25 687.9088 TotalX 31.88 249.3016 3118.261 170.256 3288.51669 yt=Ai Yi/Ai 7.82 Yb=15.64-yt 7.82 Ixx=Ix-A iyt2 1338.978 Table 4.3 Moment of Inertia Calculations For Iyy Part area(A i) Xi AixXi AixXi^2 Ii=bh^3/ 12 (Iy)I 1 3 1.5 4.5 6.75 2.25 9 2 4.48 10 44.8 448 73.17 521.17 3 3 18.5 55.5 1026.75 2.25 1029 4 5.46 2.8 15.288 42.8064 0.073 42.8794 5 5.46 17.2 93.912 1615.286 0.073 1615.3594 6 3 1.5 4.5 6.75 2.25 9 7 4.48 10 44.8 448 73.17 521.17 8 3 18.5 55.5 1026.75 2.25 1029 TotalY 31.88 318.8 4621.093 155.486 4776.54 Xt=AiXi /Ai 10 Xb=20-Xt 10 Iyy=Iy-AiXt^2 1588.579


76 Table 4.4 Moment of Inertia Calculations with Holes For Ixx Area No Ai(in2) yi Aiyi (Aiyi)yi Ii (Ix)i 1 2.8 7.8 21.84 170.352 11.43 181.782 2 2.8 7.8 21.84 170.352 11.43 181.782 3 1.6 15.48 24.768 383.4086 0.014 383.4226 Tota lHx 7.2 68.448 724.1126 22.874 746.9866 Total X 31.88 249.3016 3118.261 170.256 3288.517 Tota l Hx 7.2 68.448 724.1126 22.874 746.9866 Totalx 24.68 180.8536 2394.148 147.382 2541.53 Yt=AiY i/A 7.327942 in Yb=15.6-7.32 8.28 in Ixx=(Ix)IAyt^2 1216.246 in^4 Table 4.5 Moment of Inertia With Holes For Iyy Area No Ai(in2) Xi AiXi (Aixi)xi Ii (Iy)i 1 2.8 2.8 7.84 21.952 0.037 21.989 2 2.8 17.2 48.16 828.352 0.037 828.389 3 1.6 10 16 160 3.33 163.33 Total 7.2 72 1010.304 3.404 1013.708 TotallY 31.88 318.8 4621.093 155.486 4776.579 Tota l Hy 7.2 72 1010.304 3.404 1013.708 Total 24.68 246.8 3610.789 152.082 3762.871 Xt=AiX i/A 10 in Iyy=(Iy)I -Axt^2 1294.871 in^4


77 Table 4.6 Moment of Inertia With Holes For Second Section of Ixx Part Ai yi Aiyi Aiyi2 I=bh3/12 (Ix) =Aiyi+I 1 3 0.5 1.5 0.75 0.25 1 2 7 4.45 31.15 138.618 0.146 138.764 3 3 0.5 1.5 0.75 0.25 1 4 5.46 7.82 42.6972 333.892 84.59 418.482 5 5.46 7.82 42.6972 333.892 84.59 418.482 6 3 15.1 45.42 687.659 0.25 687.909 7 4.48 15.5 69.3504 1073.54 0.038 1073.58 8 3 15.1 45.42 687.659 0.25 687.909 Total 34.4 279.735 3256.76 170.36 3427.13 yt=Ai yi/ Ai 8.13 yb=h-yt 7.47 Ix=(Ix)-Aiyt2 1152 St=I/yb 154 Side Holes Part Ai yi Aiyi Aiyi2 I=bh3/12 (Ix) =Aiyi+I 1 2.8 7.8 21.84 170.352 11.43 181.782 2 2.8 7.8 21.84 170.352 11.43 181.782 Holes 5.6 43.68 340.704 22.86 363.564 Total 28.8 236.055 2916.06 147.5 3063.56 yt=Ai yi/ Ai 8.196347 yb=h-yt 7.403653 Ix=(Ix)-Aiyt2 1128.776 St=I/yb 152.4621


78 Table 4.7 Moment of Inertia of Spigot and Bolts(Connection) of Ixx Part Ai yi Aiyi Aiyi2 I=bh3/12 (Ix) =Aiyi+I 1 41.2 7.9375 327.025 2595.761 135.09 2730.851 2 0.785 1.625 1.275625 2.072891 0.785 2.857891 3 0.785 1.625 1.275625 2.072891 0.785 2.857891 4 0.785 1.625 1.275625 2.072891 0.785 2.857891 5 0.785 1.625 1.275625 2.072891 0.785 2.857891 6 0.785 1.625 1.275625 2.072891 0.785 2.857891 7 0.785 9.25 7.26125 67.16656 0.785 67.95156 8 0.785 6.625 5.200625 34.45414 0.785 35.23914 9 0.785 9.25 7.26125 67.16656 0.785 67.95156 10 0.785 14.25 11.18625 159.4041 0.785 160.1891 11 0.785 14.25 11.18625 159.4041 0.785 160.1891 12 0.785 14.25 11.18625 159.4041 0.785 160.1891 13 0.785 14.25 11.18625 159.4041 0.785 160.1891 Total 50.62 397.8713 3412.529 144.51 3557.039 yt=Ai yi/ Ai 7.859961 yb=h-yt 7.740039 Ix=(Ix)-Aiyt2 429.7862 St=I/yb 55.52766 All moment of iner tia calculations above is reflected to graph whic h correspond to yielding moment. Also for r ecommended max imum moment yi elding moment is multiplied with 0.6 constant value for safety.(Figure 4.39)


79 In the linear range Hand Calculations For Displacement : ksi=1000*psi kip=1000*lb E=290008ksi Ixx=1304in4 Iyy=13988in4 A=31.7in2 l=360in F=72kip Sx=167.4in3 Sy=140.3in3 M72=F*95*in M72=570ki p-ft tan $ =570/(95/12) tan $ =72 tan $ =y1/(95/12*3) y1=tan $ *95/(12*3) y1=190 M1=0.5*(95+60) M1=6.45 ki p-ft tan =y2/(95/12) y2=tan *95/12 y2=3.958 A1=(y2*95/12) A1=15.668 A2=y2*(60/12) A2=19.791A3=(6.458-y2)*60/(12*2) A3=6.24M0=A1*y1 M1=A2*y2 max=[1/(E*Ixx)]*[ I M0*M1dx] load=[1/(E*Ixx/12)]*(A1y1+A2*y2+A3*y2) load=[1/(29000*1304/12)]*(15.668*380+19.791*570+6.25*570) load=0.95in In the Linear Range Dis placements Hand Cal culations with the Sprin g(Bolts): Bending Moment: h: Distance between tw o bolts. A: Area of bolts' cross section.


80 L : Length of bolts n : Number of bolts N bolt=0.466in h=12.625in E=29000ksi n:4 Lbolt=8in Abolt= B N bolt/4 Abolt=0.17 in 2 =u/h F bolt=Fbolt/Abolt M=Fbol t*h bolt= F bolt/E u= *Lbolt M72= F bolt*E*h*Abolt M72=(u/Lbolt)*E*A bolt*h M72=( 2 *h/Lbolt)*E*Abol t*h M72=[h*E*Abolt/L bolt]* 2 Whe re, K=(h*E*Abolt* n/Lbolt) Therefore; M72=K* 2 2 =M72/[h*E*Abolt*n /Lbolt] 2 =570/[12.625*290 00*0.171*n/8] 2 =1.442*1/10 spring=15* 2 *12 spring=0.260 Gravity: Total Weight=3300lb Total Length=360in T =3300/360 T =9.25 lb/in gravit y=5* T *Lbolt4 /(384*E*Ixx) gravity=5*9.25*8*8*8*8/(384*29000*1304) gravity=1.305*1/100000


81 total= load+ spring+ gravity total=1.21In displacement In the experiment, when the sa me load (2*72000lb) a pplied to the structure, 2.32 in displacement was read. Therefore hand calculation gives 52% of actual displacement which is very accurate


82 Figure 4.1 Lvdt1 Load-Displacement Curve Figure 4.2Lvdt2 Load -Displacement Curve Figure 4.3 Lvdt3 Load Displacement Curve


83 Figure 4.5 G1 Strain-L oad Figure 4.6 G2 Principle Stress-Angle and Load Figure 4.4 G1 Principl e Stress-Angle and Loa d


84 Figure 4.9 G3 Strain-L oad Figure 4.7 G2 Strain-L oad Figure 4.8 G3 Principl e Stress-Angle-Load


85 Figure 4.11 G4 StrainLoad Figure 4.12 G5 Princip le Stress-Load Figure 4.10 G4 Princip le Stress-Angle and Loa d


86 Figure 4.13 G5 StrainLoad Figure 4.14 G6 Princip le Stress-Angle and Loa d Figure 4.15 G6 StrainLoad


87 Figure 4.16 G7 Princip le Stress-Angle and Loa d Figure 4.17 G7 StrainLoad Figure 4.18 G8 Princip le Stress-Angle and Loa d

PAGE 100

88 Figure 4.19 G8 StrainLoad Figure 4.20 G9 Princip le Stress-Angle and Loa d Figure 4.21 G9 StrainLoad

PAGE 101

89 Figure 4.22 G10 Principle Stress-Angle and Load Figure 4.23 G10 Strain -Load Figure 4.24 G11Princ iple Stress-Angle and L oad

PAGE 102

90 Figure 4.25 G11 Strain -Load Figure 4.26 G12Princ iple Stress-Angle and L oad Figure 4.27 G12 Strain -Load

PAGE 103

91 Figure 4.28 G13 Upwa rd Principle StressAngle and Load Figure 4.29 Downwar d Principle Stress-Ang le and Load Figure 4.30 G13 Strain -Load

PAGE 104

92 Figure 4.31 G14 Principle Stress-Angle and Load Figure 4.32 G14 Strain -Load Figure 4.33 G15 Princ iple Stress-Angle and L oad

PAGE 105

93 Figure 4.34 G15 Strain -Load Figure 4.35 G16 Princ iple Stress-Angle and L oad Figure 4.36 G16 Strain -Load

PAGE 106

94 Figure 4.37 Deformation on Spigot Figure 4.38 Moment-D isplacement Diagram

PAGE 107

95 Figure 4.39 Moments & Moment of Inertia

PAGE 108

96 Chapter 5 Numerical Modeling 5.1 Introduction In this chapter, the n umerical modeling of the Lead Section will be discuss ed in deta il. The Le ad is modeled using Finite Elements Program ANSYS and Feap, and the results from the modeling and the test data will be compared in the next chapter. First, the lead section was modeled and analyzed in the linear range, and the res ults agreed with the test data. In the non-linear range the analysis was perform ed under displacement control; therefore forces, strains, and stresses were predicted. The lead section had small geometric hol es on the two side faces and on the bottom face. These small holes h elped the lead to be more practic al in instrumentation. These small holes did not have a considerable effect on the stresses on the lead and were neglected in the modeling. 5.2 Defining Geometry The geometry was created in ANSYS using the following command: Preprocessor > Modeling (Create) > Key points > O n working plate Preprocessor > Modeling (Create) >Lines > Straig ht lines The geo metry of the lead has to be carefully modeled due to the complication o f connection, which links two sections by 12 bolts and one steel solid spigot. The c omplexity of the geometry can som etimes caused nume rical problems. The b ox section was modele d

PAGE 109

97 using shell element, and the bolts and the spi got were modeled usin g beam elements. Al l elements had to be defined in a th ree dimensio n box section, including the bolts and the spigot. Therefore, while defining the box geometry for shell element, the m iddle points of thickness of the box se ction were defined as k ey points. First, the key points were crea ted on the X, Y, and Z coo rdinate system. Key p oints are generally very us eful to create any geometric shape an d ma ke it easier to control or modify any kind of geometry There were a total of 46 key points used to create the whole geometry. The lines were created by using the ke y points. Through line s, the key points were connected together, an d each key point was sha red by two neighboring elements. For the spigot connection, it w as necessary to create extra key points which were numbered 45, and 46. In order to create these two key po ints, eight more key p oints were added as 9,10,11,and 12, and 41,42,43, and 44. These ten key point s belong to two elemen ts, which created the bottom shell and the spigot. Figure 5. 1 Therefore, both key points 45 and 46 belong to the bottom shell and beam (spigot) at the same time. The joints, 14-24, 16-26, 2131, and 29-19, were co mmon key points to b oth shell and beams (b olts). Through key points, lines were used to create the areas of the shell elements, but for the beam elements a line could be defined as a beam. A lso it was possible to cre ate areas directly through the key points. Using the arbitrary opti on in modeli ng it was possible to create an area either by li nes, or through the key p oints. The order of the key points were important to create an area in ANSY S; the picking of a line should not be c rossed when creating an area by lines

PAGE 110

98 5.3 Defining Element T ypes The elements were def ined using the followi ng commands: Preprocessor > Eleme nt Type > Add/Edit/Del ete The ANSYS element library contains more than 150 different element ty pes. Each element type has a unique number and a prefix t hat identifies the element category. The following categories are available in ANSYS: B E AM, CIRCUit, COMBINat ion, CONTACt, FLU ID, HF(High Frequenc y), HYPERelastic, INFINite, INTE Rface, LINK, MASS, MATRIX, MESH, PIPE, PLANE, PRETS(Pretension), SHELL, SOLID, SOURCe, SURFace, TARGEt, TRANSducer, USE R, VISCOelastic (or visco plastic). Also, the element typ es determine among other things: The degree of freedom s et (which in turn implies the disc ipline structural, therm al, magnetic, electric, quadrilateral, brick, etc.) Whether the element lie s in two-dimensional or three-dimensional space. As mentioned ear lier, the lead section is modeled using beam shell and elements and will be described as below. 5.3.1 BEAM4 Element Type Beam4 is an eleme nt with tension, compressio n, torsion, and bendin g capabilities. The element has six degrees of freedom at each node displacement in the X, Y, Z directions and rotations ROTX, ROTY, ROTZ around the X, Y, Z directions respectively. The problem faced was there were many types of elements in the same problem. For the box section, lead is modeled using shell elements, a nd all the thi cknesses of the shell

PAGE 111

99 section were considered in the linear range. During the experiment there were no distortion s. For the main connection part the spigot, two different element types were used for the linear and nonlinear cases respect ively. For th e linear case, the 3D Elastic Bea m4 for bolts connected the four corners and the spigot; for nonlinear c ase 3D Elastic Beam4 was used for bolts; 3D Plastic Beam 24 element type was used for the spigot. 5.3.2 SHELL63 Element Type The elastic Shell63 eleme nt has both bending and membrane capabili ties. These types of elements allowed for two types of loads planes and normal, t o be applied. At each node, six degrees of freedom are defined the x, y, z displacement and the rotations around the x, y, and z axes. Stress stiffening and large deflection capabilities are included. A consistent tangent stiff n ess matrix option is av ailable for use in large d eflection (finite rotation) analyses. There are som e s imilar elements whi ch are: Shell43, Shell1 81(plastic capability), and Shell9 3 (mid-side node capa bility). The Shell63 element is defined by four nodes, four thicknesses, an elastic foundation stiffness, and an orthotropic ma terial properties. Orthotropic material directions correspond to the element coordinat e directions. The elem ent coordinate system orientation is described in the coordinate systems. The element x-axis may be rotated by an a ngle THETA (in degrees). The thickness is assum ed to vary smoothly over the area of the element, with the thickness input at the four nodes but if the element has only a constant thickne ss, only TK(I) needed to be input. If the thick ness is not constant, all four thickness must be inputted separately.

PAGE 112

100 The elastic foundation stif fness (EFS) is define d as the pressure required to pro duce a unit deflection of the foundation. The elast ic foundation capabili ty is bypassed if EFS is less than or equal to zero. Element loads are described in bo th Node an d E lement Loads. Pressures can be inputted as surface loads on the element face. Positive pressure acts upon the element, and edge pressures are inputted as force per unit length. The lateral pressure loading may be equivalent to the (lumped) element load applied at the nodes or distributed ov er the face of the element. The equival ent element load produ ces more accurate stres s results with flat surface, or the elements represe nting a cu rved surface or for eleme nts supported on an elastic foundation since certain fictitious bending stress are eliminated. 5.3.3 BEAM24 Element Type Beam24 is a 3D t hinwalled beam type elem ent, with an arbitrary cr oss-section (open or closed). It has tension, compression, bending and St Venant torsional capabilities. Any open cross-section or singlecelled closed section can be used. The element has six de grees of freedom at each node: displacement in x, y, z directions and rotations about the x, y, and z axes. Also the elemen t has plastic, creep, and swelling capabilities in the axial direction as well as a user-defined cross-section. The cross-section is defined by a series of rectangular segments which are connected to each other. The orientation of the beam along its longitudinal axis is specified by a third node. The geometry, the node locations, and the coordinate system for this element are sh own as an example in Figure 5.2. The element is defined by nodes I and J in the global coordinate syste m. Node K defines a p lane (with I and J) containing the ele ment z axis. The elem ent z axis runs parallel to the centroidal line

PAGE 113

101 of the element and through nodes I and J. Node K is always required to define the element axis system and it must no t be collinear with nodes I and J. If this element is used in large deflection analysis, t he location of K is used only initially to orient t he element. The straight segments are created and input into the element y-z plane. Th e centroid and shear center loc ations of the beam, with respect to the origin, define the implied nodal offsets. In addition, real consta nts are needed to be used to describe the cross section of the beam. The input consists of the coordinates (y, z) of 20 segment points in t he element y-z plane and th e thi ckness of the corresponding segment (TK) in a y, z, TK format. All 20 points are not needed to be used in defining the cross-s ection. The segments are inputted so they make a continuous ou tline of the cross-secti on. The end-point of o ne segment i s the beginning point of the next segment. In som e cases segments may be given zero thickness in order to backtrack over previously defined segments to continue the outline. The thickness in y, z, TK is the thickn ess of th e segmen t that is defined by this point and the previous point. Therefore, the first point thickness is not used and becomes zero. Even though the spigot was cylindrical, it was appr oximated with an equivalent box section as shown in Figure 5.3, Figure 5.4. From table 5.1 the moment of inertia (Ix) of the bea m was calculated as 133in 4 while the cylindrical spigot`s moment of Inertia (Ix) wa s calculated 135in 4 in Table 5.2 5.4 Defining Real Constant The following comm and is used to define th e real constant. Preprocessor > Real Constant >Add...

PAGE 114

102 Element real constant s are properties depende nt upon element types such as cross sectional properties of a beam element. For instance, real constants for the 2D BEAM3, beam element s are : area (AREA), mom ent of inertia (IZZ), he ight (HEIGHT), shear deflection constant (SHEARZ), initial strain (ISTR N) and added mass per u nit length (ADDMAS). All element types do not require real constants, and some element types may have different real constan t values. As with element types, each se t of real constants has a reference number, and the table of reference numbe r versus real constant set is called the real constant table. While defining t he ele ment, it is necessary to point to the appropriate real constant reference number using the REAL command: Menu > Preprocessor > Cr eate > Elements >Elem Attributes If there are multi ple el ement types, a separate real constant set (different real constant reference numbers) should be us ed for each element type. The same element type can also reference several real c onstant sets. In this model three element types were pic ked for plastic deformation, and f ive sets of real constants were defined. Element Type1, SHELL63 was used with Set 1, Set 2, and Set 3. Set 1 de fined the top and bottom thickness, which was 0.32 in.; Set 2 defined the vertical thickness which was 0.4 in.; and set 3 defined the thickness of the four external top and bottom parts, which was approximated to 1 in. For element Type2, BEA M4 was used with Set 5, which defined the cross-sectional areas of bolts, and it was determined that the bolts were not yielded during the observation at the conclusion of the experiment.

PAGE 115

103 Since the connection part spigot was distorted, the spigot was modeled a s 3D BEAM24, and Set 4 was used to define its thickness and the global coordinates(y, z) of the segmental rectang ular beam. 5.5 Defining Material P roperties Most element types require material properties, and depending on application, material properties can be linear o r nonlinear. Each set of material properties ha s a material reference number with elemen t type and real constants This material referenc e numbers versus material property sets table are defined Material Table. The material prop erty set s may have multiplied withi n one analysis. ANSYS identifies each set with a unique reference number. 5.5.1 Linear Material properties The material properties are defined using the following command: Menu >Preprocessor >Ma terial Props >Material Mo dels Linear material pro perties can be constant or temperature-dependent, isotropic or orthotropic. The appropriate proper ty label must be specified as EX, EY, EZ for Young`s modulus, KXX, KYY, KZZ for therma l conductivity. For isotropic material, only the Xdirection needs to be define d ; the other directions default to the X direction value. For example, in this model the following command is used to define material property:MP,,,,,,,, MPTEMP,1,0MPDATA, EX, 1,,29000 Young`s modulus for material, ref. No. 1 is 29000 MPDATA, PRXY,1 ,, 0.30 Major Poisson's ratios ( also PRYZ, PRXZ).

PAGE 116

104 The material properties used in this model correspond to a constant, isotropic, l inear type, which was chosen from material library available through the GUI. Young`s modu lus, density, coefficient of thermal expansion Poission`s ratio, ther mal conductivity and specific heat are defined for this type of model. In this mo del the Young`s (EX) mo dules as 29,000,000 p si and Poission`s ratio (PRXY) to be 0.3. These volumes are for all element types, shell63 element, beam4 and beam24. 5.5.2 Nonlinear Mate rial Properties Nonlinear material properties are usually tabular data, su ch as plasticity data (stressstra i n curves for different hardening laws), mag netic field data (B-H cu rves), creep data, swelling data, hyper elastic material data, etc. In addition to the elasticit y modulus and Poissi on`s ratio which were assumed to be 29,000, 000psi and 0.3, tangent modulus and yielding stress need to be defined. Ta ngen t modulus model selected to be 3 percent of You ng`s mod ulus, and the yielding s tress is assumed to be 46 ksi. 5.6 Defining Mesh The command (Main Menu > Preprocessor> Me sh T ool) helps to provide a convenient path to many of the most common mesh. The Mesh Tool is an active “tool box”, not only because of num erous functions or too ls that it contains, but also once it is opened it remains until it is closed. There are ma ny short cuts in ANSYS commands via the Me sh Tool. These are can be mentioned as below:

PAGE 117

105 Controlling Smart Si zing Levels Setting element size c ontrols Specifying element shape Specifying meshing type(free or mapped) Meshing solid model e ntities Clearing meshesRefining meshes In this model, two major factors were considered wh en specif ying element shape; desired element shape and dimension of the model to be meshed. Main Menu> Preprocessor> Mesh Tool >Meshing-Mesher Opts >Meshing-Mesh> Volum es-Mapped> 4 to 6 sided First the size of ea ch elem ent was determined by the default specifications.(SMRTSIZE or DESIZE). The element sizes that the program choo ses may or may not be adequate for the analysis, dependin g on the physics of the s tructure. One way to change the mesh would be to change the default SmartSize level (SMRTSIZE) and remesh. In this model for all shell elements the size area was chosen to be two inches. For bolts, beam element size control was chosen to be 1 inch and each bolt was selected as line and defined. The solid spi got connection was size d as one inch and other sides were sized as five inches. In addition to specifying element shape, free or mapped s tyle should be chosen to mesh the model. T herefore, for both sh ell and beam elements mapped op tion was chosen to mesh the model. F or shell through four k ey points model was m es hed, and for

PAGE 118

106 beams through Pi cked Lines model was meshed. in this model. The final mesh consist of 7630 shell elements Figure 5.5 and 21 beam elements. Figure 5.6 5.7 Applying Load and Obtain The Solution In this step, the solution option was used to define the analysis type, analysis option, apply loads, specify load step options, and initiate the finite element solution. 5.7.1 Applying Load Loads are used in ANSYS as bo undary conditions(con strains, supports, or boundary field specifications) as well as other externa lly an d internally applied loa ds. The load ANSYS program is di vided in to six categorie s: DOF Constrains ForcesSurface Loads Body LoadsInertia Loads Coupled-fields Loads All loads can be applied on s olid element (key poin ts, lines, and areas or nodes and elements). For instan ce load can be specified at a key point or a node. It c an be specified on lines and areas or on nodes and element fa ces. Even though if lo ad was specified on the solid model, the program automatica lly transfer it to the nod es and elements at the beginning of the solution. There are different advantages and disadvantages of applying load on solidmodel or finite element model. In this model, loads were applied on a total of 16 nodes for both sides of the lead section. For the linear analysis, 10,000lb was applied f or each node; therefore, a total 160,000lb was applied vertically d ownward from two p oint, and it caused

PAGE 119

107 a -2.43 in displacem ent, w hich is almost the same with the experiment data. However, for a nonlinear case, the analysis was carried out under displacement control. The same 16 nodes were displaced -4 in on the same place, where the load was applied, but on the bottom plate because all displacem ent values were measured from the bottom in the experim ent. In modeling, in order to make a kind of simulation be twee n experiment and mo deling in ANSYS, displacements were ap plied on the bottom sh ell. Additionally, grav ity load which was lead`s weight was appli ed as a load on the lead system also. At the two ends of the lead to stimulate pin support (Y direction was constr ained), five node po ints 24 in far from the end, were restricted from each side. On the east side, all DOF were constrained, but on the west side just Y direction was constra ined. Therefore, whi le fixing one end, it wa s allowed to move horizontally to other end. 5.7.2 Obtain The Solution Main Menu> SolutionAfter entering dat a into the solution processor, analyses type and options can be defined. 5.8 Modeling and Experimental Results Comparison In this thesis, a c omparison between analytical and experimental resul ts is conducted The analytical results were derived using by Feap and ANSYS. Figures 5.6 and 5.7 show the global experimental and analytical load-deformation response of the structure respectively. The analytical response was derived using the finite e lement program ANSYS, as suming the structure i s behaving elastically. From the tes t results, it is observed that yieldi ng started at a load level t hat equals 144,000lb. The peak load was shown to equal 170, 000lbs and resulted in a permanent middle displacement of

PAGE 120

108 2.5” after unloading. The a nalytical results agreed well wit h the test results in the linear range. Figure 5.6 shows the global experimental and non-linear analytical load-deformation response. The analytical response was derived using the finit e element program Feap. From the figure, the analytical results agreed well with the experimental ones in both the linear and nonlinear ranges. Figure 5.8, obtained from ANSY S, shows the deform ed configuration of the entire structure at yieldi ng. The experimental principle and longitudinal strains in the top of the spigot section are sh own in Fi gures 5.10 and 5.11 res pectively. The analytic al longitudinal strain contou r plots at yielding are shown in F igure 5.11. The experi mental longitudinal strain at yielding equals 1590 :, while the analytical value equals 1830 :, The experimental longitu dinal and principle stresses ar e shown in Figures 5.12. The anal ytical longitudinal stres s distribution is shown in Figure 5.13. The max imum analytical stre ss in the spigot is shown to be equal to 46.8 ksi. Figures 5.14 and 5.15 show the contour plots of the shear strains and stresse s respectively. The m aximum shear stresses and strains occurred in the region near the connection. The previous results confirmed t he accuracy of the analytical model in predicting the local behavior of the connection.

PAGE 121

109 Figure 5.1 Connection Key Points Figure 5.2 B24 Thin B eam Example

PAGE 122

110 Figure 5.3 Thin Beam in Design Figure 5.4 General Mesh & 7630Shell Elements

PAGE 123

111 Figure 5.5 Connection Mesh & 21 Beam Elem ents Figure 5.6 Load-Middle Displacement Comparison Between Experiment and Feap

PAGE 124

112 Figure 5.7 Load-Displacement Lvdt1 Comparison Between Experiment and ANSYS Figure 5.8 Deforme d Shape

PAGE 125

113 Figure 5.10 G1 Principle Strain Figure 5.9 Connection Displacement

PAGE 126

114 Figure 5.11 Normal S train Z Direction Princi ple Strain Figure 5.12 G1 Princip le Stress

PAGE 127

115 Figure 5.13 Principle S tress Figure 5.14 XZ Shear

PAGE 128

116 Figure 5.15 Shear YZ

PAGE 129

117 Chapter 6 Conclusion This study dis cus ses the testing and modeling of a pile driving lead section manufactured by Berminghammer E ngineering Foundation. This section is denoted as a C1 5 due to the inclusion of two standar d C15x33 channel secti ons to make up the lead crosssection. This type of equipment is necessary for the installation of deep pile foundations which transfer large st ructural load to deep bea ring strata. The section was tested in the USF struct ures labo ratory under four-point bending while monitoring load, displacements and strains. In addition, a numeric al analysis of the teste d specimen was conduc ted using two finite ele ment programs, AN SYS and Feap, in order to verify and calibrate the experimental data. The conclusions of this works are described below:a) The failure mode observed during the experiment was mainly due to the yielding of the connection. Howev er the connecting plates w ere not distorted. No yielding in the Ctype box section was observed. Also, all the bolts faired well did not fail. b) The capacity of the lead section unde r the described loading cond ition has been shown to be equal to 144 kips, w hich is adequate for m ost practical c ases. T he corresponding mid-span displacem ent has been recorded as 3 inches, and the displacement

PAGE 130

118 Table 6.1 Allowable Hammer Weights for C15 under the load w as 2.1 inches. Also, corresponding strain was observed as 1590 :, and yielding moment was calculated as 570kip-ft. c) The maximum a ppli ed load was 172 kips, an d the corresponding m id-span displacement was 5.87 inches. At the location of the load (5 ` from mid-span) the displa cement at the maximum loa d was 4.1 inches. The s trains and stresses at tha t load level, recorded at the top of the spigot, were 2240 :, and 70 ksi respectively. d) The non-linear global behavior of the section could be captured accurately wi t h beam-type elements such as the ones available in the Feap l ibrary. The se beam-type elements captured accurately the loc al connec tion behavior, a three di mensional finite element model such as the one performed by ANSYS is needed. e) The allowable moment is calculated as 342ki p-ft with safety factor 0.6 Than it is correlated with the capacity o f lead section that can carry m ax weight of hamm er with the variable lead inclinatio ns. Table 6.1 gives some idea ab out capacity of C15 lea d section in Kips.

PAGE 131

119 References [1] M. J. Tomlinson, “Pile Design and Construction Practice ” ,Piling Equipments and Methods, pg 69-89, 1977 [2] Amer ican Society of Civil E ngineers, “Practical Gu idelines for the Selecti on, Design an d Installation of Piles” Installation, pg 37-52, 1984 [3] Bengt B. Broms, “Precast Piling Practice” ,Pile Driving and Piling Equipment, pg 2126,1981 [4] Brochure of Bermin ghammer Foundation Equipment Construction Limited, Wellington Street Marine Terminal, Hamilton, Ontario, Canada L8L 4Z9 [5] Brochure of Pileco, Incorporation, P.O Box 16099 Houston, TX 77222[6] Speech with Mark Rutla n, Civil Engineer in Pile Equipment, Inc, 1058 Roland Avenue Green Cove Springs, Florida 32043-8361 [7] Speech with David L. H oover, Chief Engineer Welling ton Street Marine Term inal, Hamilton, Ontorio L8L 4Z9, Canada [8] Brochure of HPSI, 1203 Ozark, North Kansas City, Missouri 64116 [9] Brochure of Pile Drivi ng,Inc. 1 058 Roland Avenue, Green Cove Springs, Fl, 32043-8361 [10] Brochure of Vulcan Foundation Equipment, 2501 Riverside Drive P.O. Box 5413 Chattanooga, TN 37406 From Web Page Updated October31,2002 [11] Bengt B. Broms, “Pr ecast Piling Practice”, Pile D riving and Pile Equipment,pg 2127,1981, London [12] Engineering Data Sheet, Measurements Group, Inc., Raleigh, North Carolina, 27611 [13] Student Manual for Str ain Gage Technology(B ulletin 309D), Measure ments G roup, Inc., Raleigh, North Carolina, 27611 [14] Joseph E. Bowles, ”Foundation Analysis and Design”, Single Piles-Static capacity and Lateral Loads; Pile/Pole Buckling, pg 867-963 1996

PAGE 132

120 [15] M J Tomlinson, ”Foundation Design & C onstruction”, Pile Foundations 2:Structural Design and Construction Methods, pg 329-370,1995 [16] [17] http://enerpac. com/ [18] James W. Dally, William F. Riley, Kenneth G. McConnel, “Instrumentation For Engineering Measurements”, Digital Recording Systems, pg 109-112, Second Edition [19] Speech with Dr. Austin Gray Mullins, Assistant Prof. / USF[20] F.E.Young, “Piles and Foundations”, Materials For Piles, pg 193-199,1981 [21] Dinesh Mohan, “Pile Foundations”, Piles, Their Installation and Structural Design, pg 3, 1988 [22]

PAGE 133

121 Appendices

PAGE 134

122 Figure A1 Positioning with Europan Type Lead Appendix A Lead Sec tion Tables

PAGE 135

123 Figure A2 U-Type Lead Section with Pin Connection Appendix A(Continued)

PAGE 136

124 Table A3 Different Types of Lead Section Appendix A (continued)

PAGE 137

125 Table A4 Properties of C15-C12 Lead sections Appendix A (continued)

PAGE 138

126 Appendix B Hammer Specifications Table B1 Air-Activated oil and fuel injection B -2005 Hammer

PAGE 139

127 Appendix B (continued) Table B2 Air-Activated Oil Fuel Injection B-3005

PAGE 140

128 Figure B3 Air-Activated Oil and Fuel Injection B-3505 Appendix B (continued)

PAGE 141

129 Appendix B (continued) Table B4 Air Activated Oil and Fuel Injection B -4005 Hammer

PAGE 142

130 Table B5 Air-Activated Oil and Fuel Injection B-4505 Appendix B (continued)

PAGE 143

131 Table B6-Air-Activate d Oil and Fuel injection B-5005 Hammer Appendix B (continued)

PAGE 144

132 Table B7 Air-Activated Oil and Fuel Injection B-5505 Appendix B (continued)

PAGE 145

133 Appendix B (continued) Table B8 Air-Activated Oil and Fuel Injection B-6005

PAGE 146

134 Table B9 Air-Activated Oil and Fuel Injection B -6505 Hammer Appendix B (continued)

PAGE 147

135 Appendix B (continued) Table B10 dcp Diesel Hammer(HPH 1200)

PAGE 148

136 Appendix B (continued) Table B11 dcp Diesel Hammer(HPH 2400)

PAGE 149

137 Appendix B (continued) Table B12 Delmag Di esel Hammers

PAGE 150

138 Appendix B (continued) Table B13 Diesel Hammers Comparison

PAGE 151

139 Appendix B (continued) Table B14 Standard Fre quency Vibrators

PAGE 152

140 Appendix B (continued) Table B15 Vibratory H ammers

PAGE 153

141 Table B16 Vibratory Hammer Comparison Appendix B (continued)

PAGE 154

142 Appendix B (continued) Table B17 ICH Hydrau lic Hammer

PAGE 155

143 Table B18 HPSI&MENC K Hammer Appendix B (continued)

PAGE 156

144 Appendix B (continued) Table B19 Vulcan Air H ammer

PAGE 157

145 Table B20 HPSI Hydra ulic Hammer Appendix B (continued)

PAGE 158

146 Appendix C Feap File Feap * Bursi composite beam (N & mm), Full Bond ,,3,2,3,2,200 parameter e=18 n=7h=1.0 i=1.0j=0.271d=15.6*hf=14*hw=0.295*h t=0.4527*h a=2.559*hb=2.165*h z=47.24*hc=0.5*hg=0.32 k=0.4l=1 coor 1,1,0.,0. e+1,,360,0. elem 1,1,1,1,2e, ,1,e,e+1 boun 2,,0,1,0 e/2-2,,0,1,0 e/2+4,,0,1,0 e,,1,1,0 disp e/2-2,,0.,-4.,0. e/2+4,,0.,-4.,0. ml1d concr_2,2 -5.34*i,-0.002,-0.05,0.1,0.*i,1.d10*i

PAGE 159

147 Appendix C (continu ed ) steel_1,6 37.0*i,29.0d3*i,0.030.,0.,0.,0.steel_2,7 37.*i,29.d3*i,0.03,20.,0.925,0.15 0.,0.,0.,0. STEEL_2,8 70.*i,28.5d3*i,0.014,20.,0.925,0.150.,0.,0.,0.STEEL_2,9 360.*i,3650.*j,0.1,15.,0.925,0.150.,50.,0.,50.BOND_1,10 2.5, 360.*i, 3.5, 12., 250.*i bond prop's u1,q1,u2,u3,q3-2.5,-360.*i,-3.5,-12.,-250.*i10.,0.4,1.3,1.3 BOND_2,12 2.5, 325., 2.5, 12.0, 125. bond prop's u1,q1,u2,u3,q3 -2.5,-325.,-2.5,-12.0,-125. 5.,0.4,2.3,2.3BOND_2,11 2.5, 360.*i, 2.5, 10., 250.*i bond prop's u1,q1,u2,u3,q3-2.5,-360.*i,-2.5,-10.,-250.*i10.,0.4,1.,1.HYSTER_1,4 1.d10,1.d-5,0.1-1.d10,1.d-5,0.1 0.,0.,0.,0.fsec18,1n,1,16,1,1.,1.-d/2+g,-f/2 d/2-g,-f/2 d/2-g,-f/2+k -d/2+g,-f/2+k n,1,16,1,1.,1.d/2-g,-f/2 d/2,-f/2 d/2,f/2,d/2-g,f/2

PAGE 160

148 Appendix C (continued) n,1,16,1,1.,1. -d/2+g,f/2-k d/2-g,f/2-kd/2-g,f/2 -d/2+g,f/2 n,1,16,1,1.,1. -d/2,-f/2-d/2+g,-f/2 -d/2+g,f/2-d/2,f/2n,1,1,16,1.,1.-d/2+l,-f/2-3-d/2+1,-f/2 -d/2,-f/2 -d/2,-f/2-3n,1,1,16,1.,1. d/2,-f/2-3d/2,-f/2d/2-1,-f/2 d/2-1,-f/2-3n,1,1,16,1.,1.d/2,f/2d/2,f/2+3 d/2-1,f/2+3d/2-1,f/2 n,1,1,16,1.,1.-d/2+1,f/2-d/2+1,f/2+3-d/2,f/2+3-d/2,f/2conn 2.8*h^2,-d/2,b,4 4,4,4,4 mate,1 user,035,1,1,1 1,1,1,1,1 0.,0. 0.,0.,0.,0. 0.,0.0.,0. 0.,0. 5,1,1,1

PAGE 161

149 Appendix C (continued) 1,1,1,1,1 0.,0. 0.,0.,0.,0. 0.,0. 0.,0.0.,0. SENS 1,1,42,0 end BATCH prop end20.,0. 100.,1.00.,0. BATCH tplotnopr dt,,0.5loop,time,200loop,,10tang,,1nexttime,200.0 disp,all reac,all stre,all next,timeend disp,e/2+1,2 reac,e/2-2,2 stop

xml version 1.0 encoding UTF-8 standalone no
record xmlns http:www.loc.govMARC21slim xmlns:xsi http:www.w3.org2001XMLSchema-instance xsi:schemaLocation http:www.loc.govstandardsmarcxmlschemaMARC21slim.xsd
leader nam Ka
controlfield tag 001 001447472
003 fts
006 m||||e|||d||||||||
007 cr mnu|||uuuuu
008 040114s2003 flua sbm s000|0 eng d
datafield ind1 8 ind2 024
subfield code a E14-SFE0000212
b SE
1 100
Uslu, Kadir.
0 245
Evaluation of pile driving lead section
h [electronic resource] /
by Kadir Uslu.
[Tampa, Fla.] :
University of South Florida,
Thesis (M.S.C.E.)--University of South Florida, 2003.
Includes bibliographical references.
Text (Electronic thesis) in PDF format.
System requirements: World Wide Web browser and PDF reader.
Mode of access: World Wide Web.
Title from PDF of title page.
Document formatted into pages; contains 161 pages.
ABSTRACT: Driving piles constitute a large portion of the high-capacity foundations used today. They transfer structural loads to deep bearing strata when adequate surficial soils are not available. The mechanisms required to install these piles generally consist of a hammer, hammer lead, a crane, and various support rigging. This study focused on lead sections, specifically, one which was manufactured by Berminghammer Foundation Equipment, Inc. The dimensions and strength of a lead section must be capable of supporting both the pile driving hammer and the longest anticipated pile for a given site. The strength of the section must be capable of withstanding hundreds of tons in compression and bending. If the lead is operated in a batter, (tilted forward, backward, or sideways) the weight of the hammer and pile causes much more bending than the vertical orientation. The cross-section details for these long steel sections vary from design to design but usually incorporate some form of bolt group, pins, and steel alignment dowels. This thesis focuses on the design, modeling, and testing of such a connection. The motivation of the study stems from a company-wide incentive to standardize the connections used to splice the Berminghammer C15-series lead section. In an effort to verify a proposed connection design, Berminghammer Foundation Engineering solicited the University of South Florida to test a full-sized lead section to failure, while monitoring the splice-connection performance.
Adviser: Mullins, Gray
lead connection.
principle strain stress.
load displacement.
capacity of lead.
Dissertations, Academic
x Civil Engineering
t USF Electronic Theses and Dissertations.
4 856