Influence of mixed-angle screw installations in CLT on the cyclic performance of commercial hold-down connections

Abstract

Mass timber products such as cross-laminated timber (CLT) are continuously gaining popularity in the construction industry due to their low carbon footprint, high strength-to-weight ratios, and good aesthetics. Seismic performance of CLT shear walls is often governed by the connections such as hold-downs and shear keys as CLT panels generally have high in-plane strength and stiffness. This paper presents a study investigating the benefit of mixed-angle screwed hold-down connections for CLT shear walls in seismic regions. A total of 42 connection tests were conducted and different connection configurations were studied. By choosing an appropriate ratio of inclined and 90° fasteners and using capacity design to prevent brittle failure modes, the connections were able to consistently achieve high strength and stiffness, and moderate to high ductility ratios. An overstrength factor of 2.3 was also derived for the tested connections. Comparisons to the predictive Eurocode 5 equations demonstrated that current design equations are reasonably accurate.