Experimental investigation of keyed shear joints subjected to a combination of compression and shear loads

Recently an increased attention has been given to the behaviour of keyed shear joints, which are typically used as vertical connections between precast reinforced concrete wall elements. The previous investigations have primarily focused on the load carrying capacity and the load-displacement relationship of connections exposed to pure shear. In practice, however, such connections typically carry shear loads in combination with normal tension or compression stresses. This paper describes an experimental setup, where biaxial compression can be applied in two principal directions by hydraulic actuators. The setup allows for an experimental investigation of combined loading on structural joints between precast concrete elements, with loads introduced in a controlled and adjustable manner. The experimental program consisted of 9 keyed shear connections between L-shaped precast concrete elements. The tests were performed with different levels of compressive normal stresses ranging from 0 - 4 MPa. The experimental results are presented as load-displacement curves, which show a systematic dependency on the level of normal compression. The cracking behaviour and the governing failure modes are discussed. Finally, a simple analytical equation is established to describe the loaddisplacement relationship of the connections.