The effect of ductile connectors on the behaviour of timber–concrete composite beams

The load-carrying capacity and ultimate deformation capacity of timber–concrete composite systems can be significantly influenced by the ductility of the connection between the two materials. The use of more ductile connections can increase the load-carrying capacity of the composite system as well as its ultimate deformation capacity. In this work, the potential increase that might be expected for these two parameters due to the use of ductile connections will be assessed through numerical simulations, taking the non-linear behaviour of the connections into account.Furthermore, the connection ductility required to achieve the maximum load capacity depends on the mechanical properties of the connection as well as on the geometric and mechanical properties of the composite system. There are certain types of connections, such as notched connections, with a very brittle behaviour, for which the failure of the composite structure might be significantly influenced by connection failure, unless very small spacing between the fasteners is used. On the other hand, ductile connections such as dowel-type fasteners can be used with large spacing since their high ultimate deformation capacity is unlikely to be reached before the failure of either the concrete or the timber member. With the aim of identifying the maximum spacing that should be allowed for each specific connector type, numerical analyses were performed with the aim of identifying the maximum spacing that should be allowed for each specific connector type so as to maximize the load-carrying capacity and possibly increase the ultimate deformation capacity.