Experimental Investigation of the Shear Resistance of CLT Panels with Unreinforced and Reinforced End Notches

This paper presents a comprehensive experimental investigation into the shear resistance and failure of both unreinforced and reinforced notched cross-laminated timber (CLT) panels. It also includes an in-depth statistical analysis, employing both one-way and three-way analysis of variance (ANOVA), to interpret the experimental findings. A total of 162 test specimens with various notch sizes in both minor and major strength directions and reinforcement using self-tapping screws (STS) were tested in bending. Unnotched CLT panels primarily failed due to rolling shear in the transverse layers. Notches reduced shear resistance and influenced failure mode and crack propagation. STS were effective in increasing shear resistance, with inclined screws being slightly more effective compared to vertical screws. For CLT panels oriented in the minor strength direction, a notch with a depth of 40% of the panel’s depth resulted in a 60% reduction in shear resistance. For these specimens, approximately half of the resistance of un-notched panels could be achieved by reinforcement. Comparing experimentally observed shear resistances to predicted values based on the available design approaches revealed that these approaches might not be conservative, particularly when the notch was within a transverse layer of CLT oriented in the minor strength direction. The findings offer insights for engineers involved in designing notched and reinforced CLT and can contribute toward developing future design guidelines.