Effect of pile orientation on the fatigue performance of jointless bridge H-piles subjected to cyclic flexural strains

This paper explores the effect of pile orientation on the low cycle fatigue (LCF) performance of steel H-piles (SPs) at jointless bridge (JB) abutments via experimental testing and finite element simulation. The experimental testing program includes 42 full scale SP specimens subjected to strong axis (SA) and weak axis (WA) bending. The SPs are tested under cyclic displacement reversals mimicking the thermal induced displacement cycles associated with the seasonal elongation and contraction of the JB in the summer and winter times. The magnitude of the axial load is also kept as a variable in the experimental testing program to investigate its effect on the cyclic performance of JB SPs. The test results are then verified via finite element simulation and a parametric numerical study is performed to further understand the cyclic behavior of SPs as a function of numerous parameters. The tests and numerical analyses results revealed that for identical cyclic flexural strain amplitudes, SPs oriented for WA bending generally demonstrate a superior performance in terms of LCF life in the presence of axial loads compared to those oriented for SA bending. Moreover, the research results showed that at large flexural strains, local buckling becomes more critical than the pile orientation for the LCF life of SPs in JBs.