Quasi-static experimental study on seismic performance of exterior shear key with different failure modes

Abstract

The shear key with horizontal failure mode manifests secondary stiffness-strengthening capacity comparing to the diagonal and slide shear modes. It is more suitable for protecting bridges that sustain multiple hazard actions. However, the seismic performance of shear keys with horizontal failure mode has seldom been addressed. This study designed and manufactured ten RC exterior shear key models involving 1:3 geometrical scaling to achieve three failure modes with specific reinforcement layouts. A quasi-static experiment was performed to investigate the seismic performance of shear keys, including crack observation, force–displacement relationship, rotation and stress distribution characteristics. The experiment results indicate that the failure mode depends on the proportion of reinforcement capacity, and can affect the maximum resistance of shear keys. The shear key with horizontal failure exhibits apparent secondary stiffness strengthening characteristics, whereas the diagonal and sliding failure modes suffer persistent reduction under large deformations. Furthermore, the diagonal shear key exhibits the highest residual capacity under severe damage. The measured data are compared with the existing analytical models in terms of both peak capacity and envelope curves, showing the models are more applicable to diagonal failure shear key than the others.