Experimental study of concrete shear keys encased by precast RC blocks

Shear keys at the interface of RC pile (hereafter refereed to RCP)) and RC blocks (hereafter referred to RCB) in integrated precast breakwater system (IPBS) have important roles in combining the RCBs into a single integrated body. Hence, a detailed estimation of shear strength between the RCB and RCP with proper shear key design is required. In the present work, the shear (joint) strength between RCB and RCP has been evaluated with different types of shear keys by conducting experiments on two different types of shear keys (full and partial shear keys). For the full shear key specimens, the maximum loads obtained increased linearly with increase in reinforcement ratios of RCB. The failure mode of full shear key specimen was found to be massive destruction failure of RCB without any failure of the shear key. On the other hand, the failure mode of partial shear key specimens showed direct shear failure at minimal failure surface of the shear key. The experimental investigation of concrete shear keys has confirmed that the failure modes vary depending on the amount of installed shear keys, highlighting the need to accurately predict the appropriate shear strength for the shear key encased by precast concrete blocks without post-tensioning. Based on the observations from experiments, a predictive equation on shear strength between RCB and RCB with partial shear keys was developed. The predictive equation considered the contribution of both shear keys and frictional shear behavior between contacted flat surfaces.