Load-bearing capacity of the steel-to-timber connections in fire temperature

Cracow University of Technology, The Faculty of Engineering, ul.Warszawska 24, Cracow 31-155, Poland

Abstract

Connections are usually the weakest parts in most structures, especially in fire conditions. The load-bearing capacity of timber structures is often limited by the resistance of steel connection between timber structural members. The temperature distribution in the cross-section as well as the influence of steel fasteners on the charring of the timber members is necessary to predict the fire resistance of the connection. This paper presents a summary of results from numerical studies on the fire behaviour of the steel connections between timber structural members. To make the three-dimensional thermal models of the joints, the FE (finite element) programme SAFIR was used. Then, the finite element models of the connections were used to analyse the temperature distribution inside cross-sections under standard ISO-fire exposure. The failure modes from the literature were used to predict the load-bearing capacity of the steel connections at elevated temperatures. The reduction of the cross-section caused by charring, the reduction of embedment strength and the reduction of steel strength at fire conditions were taken into account in the calculations.