PILE TESTING-SELECTIONS AND ECONOMY OF SAFETY FACTORS. IN: CURRENT PRACTICES AND FUTURE TRENDS IN DEEP FOUNDATIONS

Historically, while driven piles were designed conservatively by a static analysis, and then almost always installed to a driving formula, the inaccuracy of dynamic formulae for field verification of pile capacity is widely recognized. In some cases the design was verified by a static load test, performed along ASTM D1143 (1994) procedures to a maintained load of two times the design load, which engineers viewed as having the same effect as the pile having a safety factor of two. However, since static tests rarely failed, the actual safety factor was certainly higher. Modern piling practices have seen several improvements. The Federal Highway Administration (FHWA) actively promoted quick static loading procedures up to three times the design load. Computer analyses with the so-called "wave equation" with realistic models for hammer, pile and soil) have largely replaced dynamic formulae. Over the last 30 years, dynamic pile testing has become routine due to: (a) good correlation with static tests to failure; (b) the additional information it provides on hammer performance and driving stresses; and (c) the economy of this testing. Codes, both in public and private sectors, have been developed for both load and resistance factor design (LRFD) and allowable stress design (ASD) to minimize the risk of foundation failures. The selection of global safety factors (or LRFD resistance factors) to satisfy a foundation design with tolerable risk and at an acceptable cost relates to the types and amount of capacity verification performed. Based on a review of several codes, a comparison of traditional methods of dynamic formulae and static analyses with modern methods of analysis and testing is made, demonstrating the economics of the modern methods through the reduction in safety factors.

• Record URL:
  https://doi.org/10.1061/40743(142)14
• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/isbn/0784407436
• Corporate Authors:

  American Society of Civil Engineers

  Geo-Institute
  Reston, VA  United States  20191-4400
• Authors:
  • Likins, G
• Conference:
  • Contributions in Honor of George G. Gobel
  • Location: Los Angeles California, United States
  • Date: 2004-7-27 to 2004-7-31
• Publication Date: 2004-7

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 239-252
• Monograph Title: CURRENT PRACTICES AND FUTURE TRENDS IN DEEP FOUNDATIONS
• Serial:
  • ASCE Geotechnical Special Publication
  • Issue Number: 125
  • Publisher: American Society of Civil Engineers

Subject/Index Terms

• TRT Terms: Capacity restraint; Computer aided design; Load limits; Resistance (Mechanics); Safety; Soil stabilization; Static and dynamic tests; Stress ratio; Structural design; Support piles
• Subject Areas: Bridges and other structures; Design; Geotechnology; Highways; Safety and Human Factors; I24: Design of Bridges and Retaining Walls;

Filing Info

• Accession Number: 00987892
• Record Type: Publication
• ISBN: 9780784407431
• Files: TRIS
• Created Date: Mar 10 2005 12:00AM