Experimental study on post-fire mechanical properties of high strength Q460 steel: Fid-Bau Portal

Experimental study on post-fire mechanical properties of high strength Q460 steel

Wang, Weiyong / Liu, Tianzi / Liu, Jiepeng

Abstract In order to evaluate the residual strength of high strength Q460 steel structures after fire, an experimental study was undertaken to investigate the post-fire mechanical properties of high strength Q460 steel. Tensile coupons taken from high strength Q460 steel sheets were exposed to different temperatures up to 900°C, and were then allowed to cool down to ambient temperature before they were tested to failure. Two cooling methods were considered, namely; natural air cooling and cooling by water. Tensile coupon tests were conducted to obtain their post-fire stress–strain curves and associated mechanical properties (yield strength, elastic modulus, ultimate strength and elongation). It was found that the post-fire mechanical properties of high strength Q460 steel are significantly reduced below the original ambient temperature mechanical properties if they had been exposed to temperatures exceeding 600°C. Hence a new set of equations is proposed to predict the post-fire mechanical properties of high strength Q460 steel. Such post-fire mechanical property assessments allows structural and fire engineers to make an accurate prediction of the safety of fire exposed high strength Q460 steel buildings.

Highlights • Tensile tests for high strength Q460 steel were undertaken after cooling down from temperatures up to 900°C. • Post-fire mechanical properties of high strength Q460 steel were reported. • Predictive equations were given for evaluating performance of high strength Q460 steel after fire exposure. • Reference for safe evaluating and reuse of members made of high strength Q460 steel after fire was provided.