Abstract

By using an electronic database consisting of previously tested pile data and ten completed full-scale pile tests in Iowa, USA, load and resistance factor design (LRFD) resistance factors considering various construction control methods and set-ups were developed. The focus of this paper is on technology transfer from research to practice as the resistance factors derived at the end of the research required modifications. In a collaboration between a state agency, a private company and a university, this effort facilitated the development of a pragmatic LRFD design guide considering the pile set-up phenomenon that is suitable for use by design engineers. A summary of the joint effort and details of the end product as a lesson for other transportation agencies and similar future endeavours is presented in this paper, which highlights the steps beyond research needed to make the research outcomes valuable for practical use in design and construction while promoting the use of the LRFD principle for pile design.

Highlights

  • In response to the Federal Highway Administration mandate that all new bridges initiated after 1 October 2007 be designed according to the load and resistance factor design (LRFD) approach, a comprehensive research programme for developing cost-effectiveLRFD procedures for bridge piles in Iowa has been successfully completed

  • LRFD resistance factors with consideration of various construction control methods and pile set-ups documented in the report by AbdelSalam et al (2012)

  • SLT, static load test; Rm, measured pile resistance determined from SLT based on Davisson’s criterion; Re, estimated pile resistance using the Iowa Blue Book method; REOD, estimated pile resistance at END OF DRIVE (EOD); RBOR, pile resistance determined at BOR; Capwap, Case Pile Wave Analysis Program HP, steel H-pile; N/A, not available downdrag, uplift and end bearing in bedrock are illustrated in track 1

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Summary

Introduction

In response to the Federal Highway Administration mandate that all new bridges initiated after 1 October 2007 be designed according to the load and resistance factor design (LRFD) approach, a comprehensive research programme for developing cost-effective. The Iowa Blue Book method combines the a-method (Tomlinson, 1971) for cohesive soil materials and the Meyerhof (1976) semi-empirical method for cohesionless soil materials (Dirks and Kam, 1994) Using both the historical data and field test results, regional LRFD resistance factors were developed, following the American Association of State Highway and Transportation Officials (AASHTO) LRFD framework. SLT, static load test; Rm, measured pile resistance determined from SLT based on Davisson’s criterion; Re, estimated pile resistance using the Iowa Blue Book method; REOD, estimated pile resistance at EOD; RBOR, pile resistance determined at BOR; Capwap, Case Pile Wave Analysis Program HP, steel H-pile; N/A, not available downdrag, uplift and end bearing in bedrock are illustrated in track 1. The LRFD design guides and examples were developed for the state of Iowa, they can be adopted by other national and international agencies

Design guide
Design examples
Design steps
Design comparison
Conclusions
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