Shear Behavior of Different Connections for Cross-Laminated Timber-Concrete Composite Floor

his study aimed to investigate the effects of wood species, screw inclination angle, screw arrangement, notch depth, and load-to-grain direction on slip modulus and shear strength of screw connection and notch connection for cross-laminated timber (CLT) concrete floor under push-out tests. A total of 65 push-out tests were conducted to investigate slip modulus and the shear strength of screw connection and notch connection for the CLT concrete composite floor.
his study evaluated the effects of wood species, screw-to-grain angle, screw arrangements, notch depth, load-to-grain direction for screw connections, and notch connection on TCC floors under shear loads. TCC connections using different wood species of CLT panels, screw-to-grain angle, and screw arrangements showed different shear properties for slip modulus, strength, displacement, ductility ratio, and failure behaviors. The main failure behaviors for screw connections were crushing failure on CLT, cracking failure on concrete, single plastic hinge failure in the shear tension-loaded, double plastic hinges failure in the shear compression-loaded, and fracture failure of screw connectors. TCC connections using different wood species of CLT panels, notch depth, and load-to-grain direction showed different shear properties for slip modulus, strength, displacement, ductility ratio, and failure behaviors. The main failure behaviors for notch connections were crushing failure on CLT, rolling shear failure on CLT, cracking failure on CLT, crushing failure on concrete, and cracking failure on concrete.
New developed predicting equations predict slip modulus and the shear strength for TCC using screw connectors with accuracy from -30% to 13.1% for slip modulus and shear strength and for TCC using notch connectors with accuracy from -27% to 3% for slip modulus and shear strength, respectively. This study suggests the predicted equation is reliable and can be used for the design of TCC floors with screw and notch connections.