Effect of Temperature-Induced Moment-Shear Interaction on Fire Resistance of Steel Beams

The interaction between bending and shear effects in steel beams can be amplified under fire conditions due to rapid degradation in strength and stiffness properties of steel, together with temperature-induced local instability effects. This paper presents temperature-induced moment-shear (M-V) interaction phenomenon in compact (Class 1) steel beams. Results generated from numerical studies are utilized to quantify the effects of temperature-induced critical parameters influencing moment-shear interaction, shear and flexural sectional capacity, as well as instability in steel beams under fire conditions. The major findings of this work are two folds: (1) occurrence of temperature-induced instability adversely reduces shear capacity, as compared to flexural capacity, and (2) this rapid degradation in shear capacity trigger moment–shear interaction phenomenon at elevated temperatures. Eventually, this shifts failure mode in steel beams towards a shear dominant failure mechanism on the interaction envelope.