The probabilistic seismic assessment of aged concrete arch bridges: The role of soil-structure interaction

Abstract

This study aims to investigate the effect of soil-structure interaction (SSI) on the seismic response of a medium-span old concrete arch bridge in Iran's railway network, through incremental dynamic analysis (IDA). To this end, the finite element model of the bridge was developed and its dynamic properties were calibrated based on experimental results. The effect of soil-foundation flexibility was taken into consideration in the computational model. Results from analyses were summarized in IDA curves and the effect of SSI was assessed through the probabilistic framework. To this end, the failure state of bridges was evaluated and a comparison was made between the rigid and flexible base models. The mean annual frequency of exceeding the failure state of the rigid-base bridge was also compared with flexible-base models to investigate the effect of SSI on the return period of failure state of the bridge. Furthermore, the SSI effects were assessed on the confidence level of bridge safety. Results show that ignoring the SSI effect leads to an overestimation of bridge capacity as well as the confidence level of satisfying the safety state. Similarly, the return period of bridge failure increases when a rigid-base model is employed.