Experimental study on the residual seismic performance of CFDST columns after contact explosion

Abstract

Bridge columns are susceptible to various hazards throughout their service life, including accidental explosions, terrorist bombing attacks, and earthquakes. To support engineers and owners in making informed decisions regarding post-blast maintenance strategies for damaged bridges, it is crucial to gain a thorough understanding of the residual performance of affected bridge columns following the aforementioned incidents. This paper aims to investigate the residual seismic performance of concrete-filled double-skin steel tube (CFDST) columns through experimental means after being exposed to blast loading. The study consists of two phases: a field blast test and a quasi-static cyclic test, both conducted to evaluate the residual seismic performance of CFDST columns. Two circular column specimens and two square column specimens, each with similar nominal axial load-carrying capacities, were constructed and tested. One circular and one square column were initially subjected to a contact explosion before undergoing lateral cyclic loading. The remaining two columns were directly tested under cyclic loading to examine their seismic performance in an undamaged condition. By comparing the test results of the blast-damaged columns with those of the intact columns, the residual seismic performance of the blast-damaged columns is evaluated. The results indicate that the blast-damaged columns retain satisfactory lateral strength, stiffness, ductility, and energy dissipation capacity, highlighting the resilient performance of CFDST columns in a post-blast earthquake scenario. Furthermore, it was observed that the residual seismic performance of blast-damaged columns is more affected in the loading direction towards the side of blast damage. A residual index of energy absorption capacity is proposed to quantify the residual seismic capacity of blast-damaged CFDST columns. The results demonstrate that circular column exhibits better blast resistance and residual seismic performance compared to the square column. This study contributes valuable insights for the application of CFDST columns in multi-hazard scenarios involving potential contact explosions in seismic regions.