Experimental Investigation and Design Equations for Steel Strap Connections in CLT Construction

Steel strap connections are widely used in mass timber buildings. Therefore, accurately predicting their tensile behaviors and properties is crucial for the structural design of cross-laminated timber (CLT) systems. The goal of this study is to investigate the tensile properties of steel strap connections in wall-to-wall and floor-to-floor applications. The effects of different wood species, number of screws, screw spacing, construction type, and loading protocols on the tensile behaviors of the steel strap connections on CLT were investigated. Results showed that increasing the number of screws (from 6 to 12) significantly enhanced tensile resistance by up to 75%, and greater screw spacing (60 to 200 mm) strongly influenced stiffness and deformation capacity. The failure behaviors of the steel strap connection varied according to the wood species, number of screws, and screw spacing. Based on the findings, design guidelines are proposed for selecting appropriate connection configurations to resist uplift forces in CLT construction. The proposed prediction models showed good agreement with the experimental results, with average differences of 7.0% for stiffness, 18.1% for tensile resistance, and 3.9% for the ductility ratio.