Shear Reinforcement and Repair of Point-Supported CLT Floors Using Self-Tapping Screws

Abstract Mass-timber construction has become a cornerstone of sustainable development, combining low embodied carbon, renewable material sourcing, and efficient prefabrication. Among mass-timber products, cross-laminated timber (CLT) panels offer an efficient solution for two-way span, point-supported floors, where the panels are directly supported by columns. In such applications, the CLT punching shear resistance might be insufficient, requiring local reinforcement for which self-tapping screws (STS) can be adopted. The draft of Eurocode 5 provides guidance for STS reinforcement where the equivalent STS shear strength is added to the CLT rolling shear strength. The model is based on previous research on CLT panels without openings for column-to-column connections. Moreover, the effect of reinforcement zone size and the feasibility of STS repair are not fully understood. To study these parameters, more than 100 STS-reinforced point-supported CLT panels with opening for columns connections were tested. The results showed that reinforcement increased the punching shear resistance of intact panels by up to 60% and that repaired panels exhibited their original resistance. Since the Eurocode 5 model was shown to be nonconservative for all tested configurations, a modification was proposed, which more appropriately considers the reinforcement zone size. The predictions fell within 1%–11% of the experimental results presented herein and those of previous tests.