Bending Stiffness and Load–Deflection Response Prediction of Mass Timber Panel–Concrete Composite Floor System with Mechanical Connectors

Mass timber panel–concrete (MTPC) composite floor systems are currently the preferred choice of designers for multistory modern mass timber construction. An analytical model for one-way-acting composite panels has been developed to predict the effective bending stiffness and load–deflection response of MTPC composite floor systems by considering the elastic-plastic behavior of interlayer connectors and the presence of a soft acoustic layer between concrete and timber. One-way-acting composite floor panels were tested under four-point bending and vibration with various configurations to validate the developed stiffness prediction model and investigate the influence of different parameters. The experiments showed that the model can predict the effective bending stiffness of MTPC composite systems within 10% of the bending test values in the elastic range and 14% of the modal test results. The so-called gamma method, commonly used for designing composite systems, provides predictions within 12% of the test bending stiffness, on average. Although both the gamma and proposed methods yield similar results, the proposed method is more comprehensive and less restrictive in terms of the underlying assumptions that underpin the method. The proposed model is also capable of predicting the postyielding load–deflection response of the composite system. A comparison of the predicted and tested load–deflection responses indicates a reasonable agreement between the two, although the predicted effective bending stiffness tends to be higher. The predictive capability of the model for the postyielding response can be further improved by considering the influence of cracking in concrete slabs.