Resistance factors calibration and its application using static load test data for driven steel pipe piles

Abstract

This paper presents the reliability-based resistance factor calibration of driven steel pipe piles and the implementation of Load and Resistance Factor Design (LRFD) on practical design cases. Resistance factors of driven steel pipe piles were calibrated in the framework based on reliability theory using static pile load test results. The results of fifty seven load tests conducted to failure were compiled and these 57 data were divided into three different groups based on their data quality. For the three groups, reliability analyses were performed for two static bearing capacity equations and for different target reliability indices (2.0 and 2.33 for group piles and 2.5 for single piles) following the First-Order Reliability Method (FORM) and using the Monte Carlo Simulation (MCS). It is noted that the resistance factors were highly dependent on the quality of load test data. To implement the calibrated resistance factors, a case study on an actual bridge foundation design was performed. The case study result showed that, for the given target reliability index, the developed LRFD method using the resistance factors calibrated in this study could contribute to cost savings when it is compared with Allowable Stress Design (ASD) case using a safety factor of 3.0.