Methods of Interpreting Structural Incompatibility in Bored Pier Uplift Test

Abstract

This paper presents two methods of analysis of data obtained from an uplift loading test on an instrumented bored pier reinforced only by a central steel angle to which the uplift load was applied. The objective of the analyses was to estimate the unit shaft resistance profile along the length of the pier at pull-out. The analysis methods consisted of a load-movement matching technique to obtain the unit shaft resistance profile down the pier in conjunction with a stability plot to determine pier integrity, and an iterative method to determine the mobilized unit shaft resistance down the pier from measured strains. Iteration was required because the uplift load caused cracking in the concrete of the pier, resulting in a loss of structural compatibility between the concrete and the steel angle. The two methods of analysis resulted in unit shaft resistance profiles that were in good agreement, giving confidence in the results