Finite element analysis and simplified envelope curve model for RC shear key under earthquake-tsunami actions

Coastal bridges are vulnerable to the compounded effects of earthquakes and subsequent tsunamis. Their limited lateral restraints can result in critical risks such as the deck unseating or overturning. To this end, reinforced concrete (RC) shear keys are often integrated to enhance the superstructure resilience. While previous studies have investigated their seismic performance, their effects under seismic -tsunami actions remains relatively unexplored yet. This study employed finite element (FE) analysis to examine shear key properties under such conditions, with emphasis on hysteretic curves, concrete damage, and strain evolution. The FE model was developed in accordance with precedent tests, and the modeling results were also compared with tests. A simplified envelope curve model was developed using both geometry and rebar configuration, with various damage states included to reckon their seismic damages after initial earthquakes. The proposed model was validated and aligned well with test results. Further, a framework was proposed to determine the envelope curve for bridges at different damage stages. This study aims to provide insights into the seismic -tsunami analysis on coastal bridges by considering their varying properties under seismic and tsunami actions.