American Society of Civil Engineers

Improving Prediction of the Load-Displacement Response of Axially Loaded Friction Piles

by Muhannad T. Suleiman, A.M.ASCE, (Assistant Professor, Department of Civil and Environmental Engineering, Lehigh University, 326 STEPs Building, Bethlehem, PA, 18015. E-mail:, Sherif S. AbdelSalam, (Graduate student and Research Assistant, Department of Civil, Construction, and Environmental Engineering, Iowa State University, 355 Town Engineering, 50011-3232. E-mail:, and Sri Sritharan, M.ASCE, (Wilson Engineering Professor and Assoc. Chair, Department of Civil, Construction and Environmental Engineering, Iowa State University, 376 Town Engineering, 50011-3232. E-mail:
Section: Foundations and Ground Improvement, pp. 36-45, (doi:

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Document type: Conference Proceeding Paper
Part of: Geo-Frontiers 2011: Advances in Geotechnical Engineering
Abstract: This paper describes a Modified Borehole Shear Test (mBST) and a Modified Direct Shear Test (mDST) and their use to improve the prediction of the load-transfer (or t-z) analysis of axially loaded friction piles. The mBST and mDST enable direct measurement of the t-z curves along the soil-pile interfaces for cohesive soils in the field and for cohesionless soils in the laboratory, respectively, thereby improving the prediction of load-displacement response of piles. As part of this study, two full-scale instrumented static vertical load tests were conducted on steel H-piles and the t-z analysis was used to model these piles utilizing the TZPILE software. In these models, t-z curves established from the mBST and mDST as well as those currently used based on Cone Penetration Test (CPT) data were used to predict the pile load-displacement response. By comparing to the measured responses from static load tests (SLTs), the mBST- and mDST-based models produced closely comparable load-displacement responses. In contrast, the CPT-based models over predicted the loads at a given target displacement, underscoring the benefits of the mBST and mDST.

ASCE Subject Headings:
Axial loads
Drilled shafts