Vibration Performance and Stiffness Properties of Mass Timber Panel-Concrete Composite Floors with Notched Connections

Mass timber panel-concrete composite (MTPCC) floors combine timber and concrete through high-performance connections to create an efficient floor system with high stiffness, high strength, and low self-weight. Previous research on MTPCC floors focused on improving the composite efficiency of floors under static loadings by testing different types of shear connectors. The dynamic performances of MTPCC floors, which can govern the floor span and thickness, have not been well investigated. In this study, vibration tests were conducted on glued-laminated timber panels and notch-connected MTPCC floors with different spans, thicknesses, and connection layouts. The dynamic properties, including natural frequencies, damping ratios, and mode shapes, were obtained for floors under different supporting conditions. Test results showed that MTPCC floors with a 6-m span had fundamental natural frequencies generally higher than 8 Hz. The addition of the concrete layer to the bare timber panels improved the floor fundamental natural frequency and damping. Deflection tests and walking tests were performed on MTPCC floors to evaluate the floor vibration serviceability performance, and it was found that the existing design criteria predicted inconsistent results. The flexural stiffness of MTPCC floors determined from vibration and deflection tests was close to full composite, while only partial composite action in the composite floors was achieved under a higher load level in destructive bending tests.