Fire design of steel-to-timber dowelled connections

The load-carrying capacity of timber structures is often limited by the resistance of the connections. Thus, highly efficient connections such as multiple shear steel-to-timber connections with slotted-in steel plates and steel dowels are needed for an efficient design. The load-carrying capacity of multiple shear steel-to-timber dowelled connections with slotted-in steel plates in fire primarily depends on the temperature-dependent reduction of embedment strength of the timber members. In order to accurately predict the fire resistance of the connection, knowledge of the temperature distribution in the cross-section as well as the influence of steel elements (slotted-in steel plates and steel dowels) on the charring of the timber members is essential.Based on an extensive experimental and numerical analysis, a design model for the calculation of the load-carrying capacity in fire of multiple shear steel-to-timber dowelled connections with slotted-in steel plates subjected to tension was developed and is presented. The design model is in analogy with the reduced cross-section method according to EN 1995-1-2 commonly used for the fire design of timber members. The proposed design model takes into account different geometries of the connection and the influence of the steel elements on the temperature distribution in the cross-section.