Experimental evaluation of angle bracket connections in CLT structures under in- and out-of-plane lateral loading

Abstract

In cross laminated timber (CLT) structures, angle brackets are commonly used in wall-to-floor connections to transfer the shear in seismic and wind loads. In reality, these connections could experience multi-directional forces under in- and out-of-plane lateral loads. A two-phase experimental program consisting of 12 monotonic tests in the first phase, and 24 monotonic and 24 cyclic tests in the second phase was conducted to investigate the behaviour of CLT wall-to-floor connections, connected with two different sizes of steel angle brackets and four types of fasteners, under uplift, in-plane shear, and out-of-plane shear loads. The performance of the connections was evaluated in terms of strength, stiffness, ductility, energy dissipation capacity, and failure modes. Results show that small diameter fasteners are more desirable for wood-to-wood angle bracket connections in terms of failure modes, load-bearing capacity and stiffness. Specimens exhibited considerable ductile performance under both uplift and in-plane shear loads due to combinations of yielding of brackets and yielding or pull-out of screws. Connections loaded under out-of-plane tension may fail in splitting of CLT panels. Fully-threaded screws led to higher strength, stiffness and energy dissipation capacity but less ductility compared to partially-threaded screws in angle bracket connections.