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Experimental tests of cross-laminated timber (CLT)-concrete composite floor panels were conducted. The tests consisted of linear-elastic tests of square CLT-concrete composite panels with a novel shear connector to determine elastic orthotropic plate properties. After the linear-elastic tests, the panels were subjected to a patch load at the center of the panel and tested to failure. To investigate load transfer across longitudinal joints between adjacent panels, nonuniform bending tests were conducted. Results from the experimentally measured orthotropic plate properties showed that the shear connector increased the bending stiffness in the weak direction of the panel compared to prior test results using conventional shear connectors. The tests to failure exhibited larger differences in behavior between the strong and weak orientations of the specimens, with both showing substantial inelastic behavior prior to failure. Numerical finite element models of the patch-load test showed good agreement with experimental results. Analytical formulas using the obtained orthotropic plate properties did not agree with experimental results for the patch-load at linear scales, suggesting the simplified method is currently not suited for CLT-concrete two-way bending. Load-transfer tests found that the reinforced concrete topping is capable of transferring load across the longitudinal joint of two parallel panels to enable two-way bending of composite timber–concrete floors and that the addition of a plywood spline with closely spaced screws enables a higher degree of force transfer. [ABSTRACT FROM AUTHOR]

• Twenty in-plane shear tests on CLT surface spline connections were performed. • Splines were constructed using nails and three different screw spacings. • Nail spline connections were more ductile than the screw connections. • An engineering performance model for the CLT splines is presented. Cross-laminated timber (CLT) panels have been used as structural diaphragm elements that form the primary lateral force-resisting system in mass-timber buildings. To better understand the overall performance of CLT diaphragms, an experimental program including monotonic and cyclic in-plane shear panel-to-panel spline connections tests was conducted. The spline connections were constructed using nails and screws with different spacings. Experimental results from the testing program allow for characterization of the performance of the connection systems in terms of elastic stiffness, strength, and ductility. Based on the results of this specific testing program, nailed spline connections displayed similar performance in terms of stiffness and strength and were more 58.7% more ductile than the screw connections, which is partly explained by the larger overstrength factors observed for the screw connections. A simplified performance model is presented to aid designers in determining the elastic, inelastic, and post-peak force parameters of the various spline connections tested. [ABSTRACT FROM AUTHOR]