Behavior of dowelled and bolted steel-to-timber connections exposed to fire

This study focuses on the load distributions among fasteners in steel-to-timber connections loaded in tension parallel-to-grain under fire exposure. The experimental results of some types of connections with various geometrical configurations are available. The influence of the type of fasteners (bolt, dowel) on the thermo-mechanical behavior of the connections is studied. A three-dimensional finite element model validated on the basis of experimental results is used. Good agreements were observed between the simulated and the experimental values of temperatures and failure times. The type of metal fasteners is crucial to the thermo-mechanical behavior of connections. In the studied connections, one bolt is used in each row of fasteners to prevent the separation between the assembled members. The presence of the bolts greatly influences the behavior of the connections mainly under fire. Various geometrical configurations of connections with only dowels or changing the positions of the bolts are studied. An analytical approach is proposed, from a specific type of connections, by varying some influent geometrical characteristics. A numerical experimental design is realized from the calculated time to failure of the connections.

► FE model used to simulate the behavior of multiple fasteners joints in fire.
► The position of bolts and dowels is analyzed regarding the fire performance.
► Experimental results used to validate the thermo-mechanical model of timber connections.
► Analytical approach proposed to predict the fire resistance using numerical experimental design.