Experimental test of coupling effect on CLT angle bracket connections

In this paper, the coupling effect of axial and lateral loading on Cross Laminated Timber (CLT) angle bracket connections is investigated through experimental tests. Monotonic and cyclic tests of the connections were carried out in shear, with different levels of constant force applied in tension simultaneously. Specimens subject to four different levels of tension forces were tested and the results were analyzed in terms of key mechanical characteristics of those connections including strength, stiffness, ductility, strength/stiffness degradation, equivalent viscous damping and energy dissipation. The results show that shear and tension for angle brackets are strongly coupled. Co-existent of tension force reduces the lateral strength and stiffness capacity of the connection significantly. Under complex loading, the gap between nail and wood embedment mitigates and the friction increases, resulting in the reduction of pinching effect; hence, the energy dissipation capacity drops under larger deformation. The study gives a better understanding of hysteretic behavior of angle bracket connections for CLT where rocking motions occur, and provides reliable data for future numerical analysis of CLT structures.