Behaviour of reduced web section connections in fire - an experimental and numerical study

Abstract

This paper presents a comprehensive investigation into the fire behaviour of steel beams with reduced web section (RWS) connections, which are commonly employed to enhance ductility in seismic design. Despite their increasing popularity in real applications in steel design for seismic regions, the performance of RWS connections under fire conditions has not been thoroughly investigated. This study details the results of the first fire test conducted on an RWS connection, carried out at the fire laboratory of Tampere University. Complementing the experimental work, a finite element model was developed and validated against the test data, allowing for an extensive parametric study. Key variables examined include steel grade, load ratio, and geometric properties of the elliptical cuts in the web. The results reveal that duplex stainless steel grade 1.477 offers the greatest fire resistance among the materials tested, while carbon steel performs the least well. Furthermore, increasing the load ratio generally reduces fire resistance, with carbon and austenitic stainless steels being particularly sensitive to this parameter. Based on these observations, design recommendations are provided to optimize the fire resistance of RWS connections.