by JH Long · 2009 · Cited by 18 — on the pile being driven, the hammer being used, and the soil into which the pile is Pile Driving Analyzer (PDA), and developed a fifth method, called the
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Comparison of Five Different Methods for Determining Pile Bearing Capacities Prepared for Wisconsin Highway Research Program Andrew Hanz WHRP Program Manager 3356 Engineering Hall 1415 Engineering Dr. Madison, WI 53706 by James H. Long, P.E. Associate Professor of Civil Engineering Josh Hendrix David Jaromin Department of Civil Engineering University of Illinois at Urbana/Champaign 205 North Mathews Urbana, Illinois 61801 Contact: Jim Long at (217) 333-2543 jhlong@uiuc.edu
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Wisconsin Highway Research Program #0092-07-04 Comparison of Five Different Methods for Determining Pile Bearing Capacities Final Report by James H Long Joshua Hendrix David Jaromin of the University of Illinois at Urbana/Champaign SUBMITTED TO THE WISCONSIN DE PARTMENT OF TRANSPORTATION February 2009
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– i – ACKNOWLEDGMENTS. iv DISCLAIMER.. vi Technical Report Documentation Page. vii Executive Summary.. ix Project Summary.. ix Background ix Process.. x Findings and Conclusions xii Chapter1. 1 1.0 INTRODUCTION. 1 Chapter2. 3 2.0 METHODS FOR PREDICTING AXIAL PILE CAPACITY.. 3 2.1 INTRODUCTION 3 2.2 ESTIMATES USING DYNAMIC FORMULAE.. 3 2.2.1 The Engineering News (EN) Formula. 4 2.2.2 Original Gates Equation.. 5 2.2.3 Modified Gates Equation (Olson and Flaate).. 5 2.2.4 FHWA-Modified Ga tes Equation (USDOT).. 6 2.2.5 Long (2001) Modification to Original Gates Method. 6 2.2.6 Washington Department of Transportation (WSDOT) method. 7 2.3 ESTIMATES USING PILE DRIVING ANALYZER (PDA). 7 2.4 EFFECT OF TIME ON PILE CAPACITY 9 2.5 CAPWAP (CASE Pile Wave Analysis Program). 10 2.6 SUMMARY AND DISCUSSION 11 Chapter3.. 13 3.0 DATABASES, NATIONWIDE COLLECTION AND WISCONSIN DATA 13 3.1 INTRODUCTION. 13 3.2 FLAATE, 1964 .13 3.3 OLSON AND FLAATE, 1967 14 3.4 FRAGASZY et al. 1988, 1989. 14 3.5 DATABASE FROM FHWA 15 3.6 ALLEN (2005) and NCHRP 507.. 15 3.7 WISCONSIN DOT DATABASE. 15 3.8 SUMMARY.. 16 Chapter4.. 30 4.0 PREDICTED VERSUS MEASURED CAPACI TY USING THE NATIONWIDE DATABASE.. 30 4.1 INTRODUCTION. 30 4.2 DESCRIPTION OF DATA.. 30 4.3 COMPARISONS OF PREDICTED AND MEASURED CAPACITY.. 31 4.4 WISC-EN METHOD. ..33 4.4.1 Wisc-EN vs. SLT. 33 4.4.2 Wisc-EN vs. PDA (EOD) and CAPWAP (BOR).. 34 4.5 WASHINGTON STATE DOT METHOD (WSDOT).. 34
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– ii – 4.5.1 WSDOT vs. SLT ..34 4.5.2 WSDOT vs. PDA and CAPWAP 34 4.6 FHWA-GATES METHOD.. 35 4.6.1 FHWA-Gates vs. SLT 35 4.6.2 FHWA-Gates vs. PDA(EOD) and CAPWAP(BOR).. 35 4.7 PDA(EOD) AND CAPWAP(BOR). 35 4.8 DEVELOPMENT OF THE fiCORRECTEDflFHWA-GATES METHOD 36 4.9 SUMMARY AND CONCLUSIONS.. 37 Chapter 5. 79 5.0 PREDICTED VERSUS MEASURED CAPAC ITY USING THE DATABASE COLLECTED FROM WISCONSIN DOT.79 5.1 INTRODUCTION. 79 5.2 DESCRIPTION OF DATA.. 79 5.3 WISC-EN AND FHWA-GATES COMPARED WITH PDA-EOD. 81 5.4 WISC-EN AND FHWA-GATES COMPARED TO PDA-BOR. 82 5.4.1 Wisc-EN 84 5.4.2 FHWA-Gates.. 84 5.5 STATIC LOAD TEST RESULTS 85 5.6 FHWA-GATES COMPARED TO WISC-EN.. 86 5.7 EFFECT OF HAMMER TYPE.. 87 5.7.1 Wisc-EN 87 5.7.2 FHWA-Gates.. 87 5.7.3 PDA-EOD 88 5.8 Wisc-EN, FHWA-Gates, PDA-EOD compared to CAPWAP-BOR. 88 5.8.1 Wisc-EN 88 5.8.2 FHWA-Gates.. 88 5.8.3 PDA-EOD 89 5.9 WSDOT Formula.. .90 5.9.1 PDA-EOD 90 5.9.2 SLT. 90 5.9.3 CAPWAP-BOR.. 91 5.10 CORRECTED FHWA-GATES FORMULA.. 92 5.10.1 PDA-EOD.. ..92 5.10.2 SLT 92 5.10.3 CAPWAP-BOR. 93 5.11 CONCLUSIONS.. 93 5.11.1 PDA-EOD.. ..93 5.11.2 Wisc-EN.. ..94 5.11.3 FHWA-Gates 95 5.11.4 WSDOT Formula.. 96 5.11.5 Corrected FHWA-Gates. 97 Chapter6 130 6.0 RESISTANCE FACTORS AND IMPACT OF USING A SPECIFIC PREDICTIVE METHOD 130 6.1 INTRODUCTION.. 130 6.2 SUMMARY OF PREDICTIVE METHODS.. 130 6.3 FACTORS OF SAFETY AND RELIABILITY. 131 6.4 RESISTANCE FACTORS AND RELIABILITY. 132 6.4.1 First Order Second Moment (FOSM). 132 6.4.2 First Order Reli ability Method (FORM).. 133 6.5 EFFICIENCY FOR THE METHODS AND RELIABILITY. 134 6.6 IMPACT OF MOVING FROM FS DESIGN TO LRFD.. 135
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– iii – 6.6.1 Factor of Safety Approach 135 6.6.2 Reliability Index for Factor of Safety Approach and LRFD.. 135 6.6.3 Impact of Using a More Accurate Predictive Method.. 137 6.7 CONSIDERATION OF THE DISTRIBUTION FOR Q M/QP138 6.7.1 Resistance Factors Based on Extremal Data.. 138 6.7.2 Efficiency Factors Based on Extremal Data 139 6.7.3 Impact on Capacity De mand using Efficiency Factors Based on Extremal Data.. 140 6.8 SUMMARY AND CONCLUSIONS 140 Chapter7 153 7.0 SUMMARY AND CONCLUSIONS 153 Chapter 8.. 158 8.0 REFERENCES.. ..158
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– iv – ACKNOWLEDGMENTS The authors acknowledge the contributions from the technical oversight committee: Mr. Jeffrey Horsfall, Wisconsin Department of Transportation, Mr. Robert Andorfer, WisDOT, Mr. Steven Maxwell, and Mr. Finn Hubbard. These members provided helpful guidance to ensure the project addressed issues relevant to WisDOT. We also are grateful for the assistance provided by Mr. Andrew Hanz who ensured the administrative aspects ran smoothly.
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– vi – DISCLAIMER This research was funded through the Wis consin Highway Resea rch Program by the Wisconsin Department of Transportation and the Federal Highway Administration under Project # (0092-07-04). The contents of this report reflect the views of the authors who are responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views of the Wisconsin Department of Transportation or the Federal Highway Administration at the time of publication. This document is disseminated under the sponsorship of the Department of Transportation in the interest of information exchange. The United States Government assumes no liability for its contents or use thereof. This report does not constitute a standard, specification or regulation. The United States Government does not endorse products or manufacturers. Trade and manufacturers™ names appe ar in this report only because they are considered essential to the object of the document.
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– vii – Technical Report Documentation Page 1. Report No. WisDOT 0092-07-04 2. Government Accession No 3. Recipient™s Catalog No 4. Title and Subtitle Comparison of Five Different Methods fo r Determining Pile Bearing Capacities 5. Report Date 6. Performing Organization Code 7. Authors James H. Long, Joshua Hendrix, David Jaromin 8. Performing Organization Report No. WisDOT 0092-07-04 9. Performing Organization Name and Address Department of Civil Engineering University of Illinois 205 North Mathews/Urbana, Illinois 61822 10. Work Unit No. (TRAIS) 11. Contract or Grant No. 12. Sponsoring Agency Name and Address Wisconsin Department of Transportation 4802 Sheboygon Avenue Madison, WI 73707-7965 13. Type of Report and Period Covered Final Report Jan 2007-Aug2008 14. Sponsoring Agency Code 15. Supplementary Notes Research was funded by the Wisconsin DOT through the Wisconsin Highway Research Program. Wisconsin DOT Contact: Jeffrey Horsfall (608) 243-5993 16. Abstract The purpose of this study is to assess the accuracy and precision with which five me thods can predict axial pile capacity. The methods are the Engineering News formula currently used by Wisconsin DOT, the FHWA-Gates formula, the Pile Driving Analyzer, the Washington State DOT. Further analysis was conducted on the FHWA-Gates method to improve its ability to predict axial capacity. Improvements were ma de by restricting the application of the formula to piles with axial capacity less than 750 kips, and to apply adjustment factors based on the pile bein g driven, the hammer being used, and the soil into which the pi le is being driven. Two databases of pile driving information and static or dynamic load tests were used evaluate these methods. Analysis is conducted to compare the impa ct of changing to a more accurate pred ictive method, and incorporating LRFD. The results of this study indicate that a ficorrectedfl FHWA-Gates and the WSDOT formulas provide the greatest precision. Using either of these two methods and changing to LRFD should increase the need for foundation (geotechnical) capacity by less than 10 percent. 17. Key Words piles, driving piles, pile fo rmula, pile capacity, LRFD, resistance factor 18. Distribution Statement No restriction. This document is available to the public through the National Tech nical Information Service 5285 Port Royal Road Springfield VA 22161 19. Security Classif.(of this report) Unclassified 19. Security Classif. (of this page) Unclassified 20. No. of Pages 21. Price Form DOT F 1700.7 (8-72) Reproductio
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– ix – Executive Summary Project Summary This study was condu cted to assess the accuracy and precision with which four methods can predict axial pile capacity. The methods are the Engineering News formula currently used by Wisconsin DOT, the FHWA-Gates formula, the Pile Driving Analyzer, and the method developed by Washington State DOT. Additional analysis was conducted on the FHWA-Gates method to improve its ability to predict axial capacity. Improvements were made by restricting the application of the formula to piles with axial capacity less than 75 0 kips, and to apply adjustment factors based on the pile being driven, the hammer being used, and the soil into which the pile is being driven. Two databases of pile drivin g information and static or dynamic load tests were used evaluate these methods. Analyses were condu cted to compare the impact of changing to a more accurate predictive method, and incorporating LRFD. The results of this study indicate that a ficorrectedfl FHWA-Gates and the WSDOT formulas provide the greatest precision. Using either of these two methods and changing to LRFD should increase the need for foundation (geotechnical) capacity by less than 10 percent. Background The Wisconsin Department of Transportation (WisDOT) often drives piling in the field based on the dynamic formula known as the Engineering News (EN) Formula. The Federal Highway Administra tion (FHWA), as well as others, have provided some evidence and encouragement for state DO Ts to migrate from the EN formula to a more accurate dynamic formula known as the FHWA-modified Gates formula. The behavior and limitations of the FHWA-modified Gates formula need to be defined more quantitatively to allow WisDOT to assess when use of the Gates method is appropriate. For example, there is eviden ce that the Gates met hod may be applicable only over a limited range of pile capacity. Furthermore, there needs to be a clear quantitative comparison of predictions made wi th FHWA-modified Gates and
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