Experimental and Numerical Study on Shear Buckling of Composite Plate Girders in Fire

Abstract Steel‐concrete composite plate girders are key structural elements used in loadbearing structures of high capacity or long spans. Despite lateral stiffeners, their slender webs remain prone to web out‐of‐plane shear buckling, especially under high temperatures, such as during fires. However, the shear buckling behaviour of these girders, both at ambient and elevated temperatures, requires further study. This research focuses on experimental and numerical study of shear buckling in steel‐concrete composite plate girders under fire exposure. Along with the largescale elevated temperature tests a computational framework using ABAQUS is developed and validated against experimental results, to analyse the structural fire response of composite plate girders as well as further influencing parameters. As a result of this integrated study, it is shown that higher web slenderness and panel aspect ratio, along with partial shear connection, reduced top flange rigidity, higher load ratio and lower material grade reduce the overall fire resistance. Furthermore, it is shown that thermal gradients and thermal expansion lead to accelerated web shear buckling. Finally, the concrete slab enhances stiffness and insulates the top flange, slowing its heating rate and taking 50% of the total shear force.