Experimental investigation and finite element analysis for seismic capacity prediction of RC shear keys with different failure modes

Exterior reinforced concrete (RC) shear keys are widely used to protect bridge superstructures from lateral unseating and overturning during major earthquakes. The peak capacity and envelope curve of the shear keys are essential parameters for evaluating their performance. This study was conducted as a follow-up to the experimental research by the authors, which aimed to investigate the seismic properties of shear keys. In this subsequent research, RC shear keys were numerically simulated using the ABAQUS software to reveal the damage evolution and strain development. The modeling results were compared with test observations, where three typical failure modes were considered including diagonal, horizontal, and sliding failures. The results are in good agreement with the experiments in terms of the envelope curves for the diagonal and horizontal failure shear keys, but they underestimate the residual strength of the sliding failure shear key. The strain distribution and concrete damage are in good accord with the field observations. Through comparison with experimental tests, this study developed three analytical models to evaluate the performance of each failure mode, which yielded better predictions than the existing methods. Ultimately, these findings enhance the understanding of the shear key behavior and its effectiveness in protecting bridges against seismic hazards. •Three failure modes of shear keys were studied including diagonal shear, horizontal shear and sliding shear failures.•Capacity ratio and joint condition are the major factors that affect the failure mode of RC shear key.•Horizontal failure mode exhibits a secondary strengthening in stiffness, while diagonal and sliding failure modes show continuous decline.•Numerical modeling was conducted to study the failure mechanism of RC shear keys, with analytical models proposed to predict peak capacity.•Horizontal failure mode was suggested for protecting superstructure, while diagonal and sliding failure modes are suitable for substructure.