Experimental study on seismic performance of different failure modes of RC shear keys

The capacity of horizontal failure shear keys is larger than diagonal and slid-ing failure modes owing to its secondary stiffness-strengthening stage. Nevertheless, the seis-mic performance of shear keys with horizontal failure mode has received limited attention yet. This investigation involved the design and fabrication of ten reinforced concrete (RC) exterior shear key specimens. A quasi-static experiment was conducted to assess the seismic perform-ance of these shear key under cyclic load effects. The concerned properties include crack devel-opment, force-displacement relationship, rotation deformation and the stress distribution. The experimental results indicate that the failure mode is dependent on the capacity ratio between reinforcements. Horizontal failure shear key exhibits apparent second-rising of stiff-ness after its peak capacity, while the diagonal and sliding failure shear key undergo continu-ous decline under substantial deformations. Comparing the measured data with existing prediction models indicates that the models are more applicable to shear keys with diagonal failure mode as opposed to the others.