Predictive Models for the Stiffness of Vertical Screws as Shear Connection in Timber-Concrete Composite Floors

The stiffness, strength, and arrangement of the shear connection play a crucial role in the design of timber-concrete composite (TCC). This paper reviews the available analytical models for prediction of the stiffness of TCC shear connections. The methodology of different analytical models for stiffness of the mechanical fastener TCC connection is discussed and the accuracy of these models is examined based on push out test results for shear connectors. The simplified stiffness models underestimated the experimental data of normal wood screw with an error ranging approximately 10–40%, whereas the models based on Winkler’s theory were inaccurate and calculated a much lower stiffness compared to that of experimental test with an error of approximately 60%. The reasons attributed to inaccuracy of the stiffness models are described. This paper recommends further investigation on the prediction of foundation moduli of timber and concrete as the main input parameters of the models based on the Winkler’s theory.