Experimental and theoretical evaluation of TCC connections with inclined self-tapping screws

Timber-concrete composite (TCC) structures have become a wide-spread technique to realize new composite floors or improve existing ones. The key-point to guarantee adequate mechanical performance to these composite structures is the use of connectors characterized by adequate strength and stiffness between timber beam and concrete slab. Modern cylindrical connectors, such as self-tapping screws, are rising interest because they combine high performance mechanical properties and quickness of execution. In this paper, a simplified theoretical approach to calculate shear strength and stiffness of TCC joints made with inclined screws is suggested and compared to current design procedures. Furthermore, a report on short-term push-out tests of TCC joints realized with inclined self-tapping screws carried out varying fastener arrangement, diameter and concrete type is given. A comparison between the results obtained with the theoretical method and experimental tests is reported and critically discussed in terms of both strength and stiffness.