Numerical analysis of in- and out-of-plane coupling effects on angle bracket connections in CLT structures

Abstract

Angle bracket connections are commonly used to transfer shear loads in cross laminated timber (CLT) structures. In reality, these connections may experience multiple-direction loads simultaneously in the wind and seismic events. A two-phase numerical program was carried out to assess the coupling effect of biaxial loading on the performance of CLT wall-to-floor angle bracket connections. In phase I, a 3D finite element model of connections was developed using ABAQUS software and verified with the data from experimental tests previously carried out by the authors. In Phase II of the study, the verified model was used to simulate the performance of connections under three biaxial loads, i.e., in-plane shear and uplift, in-plane shear and out-of-plane outward shear, and in-plane shear and out-of-plane inward shear. The coupling effect on the performance of the connections was evaluated in terms of strength, stiffness, ductility, and failure modes under biaxial loads, and compared with the scenario where the connection was only loaded in in-plane shear. Results show that the application of biaxial loading may considerably decrease the in-plane shear performance of the angle bracket connections when the secondary load is more than 50% of its monoaxial resistance, while the effect of biaxial loading is limited when the secondary load is less than 25% of its monoaxial resistance.