Comparative Assessment of RC and CFST Columns in Rigid-Frame Bridges Subjected to Horizontal and Vertical Ground Motions

Abstract

The study aims to explore the application of concrete-filled steel tube (CFST) columns as a more resilient and sustainable alternative to vulnerable reinforced concrete (RC) columns in rigid-frame bridges prone to significant damage during strong earthquakes with large vertical ground motion intensities. A series of multi-axis hybrid simulations on a rigid-frame bridge structure are conducted, with circular and square CFST column cross-sections. The structure is subjected to combined horizontal and vertical ground motions using the state-of-the-art hybrid testing facility, the multi-axis substructures testing (MAST) system at Swinburne University of Technology. The test results of the CFST columns are then compared with those of a previous hybrid testing study on circular RC columns used in the construction of the same bridge structure. The study utilizes the classic performance-based earthquake engineering (PBEE) framework to compare the observed damage states and quantify the repair sustainability metrics, including repair cost (economic), repair downtime (social), and repair carbon emissions (environmental). The research findings confirm the superior seismic performance of CFST columns and highlight their potential in enhancing the resilience and sustainability of critical and post-disaster bridges that are susceptible to strong vertical ground motions.