Structural fire performance of steel-concrete composite girders in web shear buckling: Advanced numerical analysis

Abstract

This study investigates the structural fire performance of steel-concrete composite plate girders prone to web shear buckling – a critical failure mode intensified by rapid and uneven heating in fire conditions. A validated numerical model developed in ABAQUS Software is used to simulate fire scenarios and assess key parameters affecting girder behavior. Through a series of parametric case studies, the influence of web geometry, load ratio, material grade, and shear connection on fire resistance is systematically explored. Results show that reducing web slenderness and panel aspect ratio significantly improves fire performance, while increasing material strength and shear connection offers limited benefits. The redistribution of shear forces during heating reveals that, prior to collapse, the concrete slab carries more than half of the total shear load due to its lower temperature and higher relative stiffness. The study also evaluates the applicability of existing analytical models for shear strength under elevated temperatures, showing improved prediction accuracy when the contribution of the concrete slab is included. This research provides new insights into the behavior of steel-concrete composite girders in fire and offers a robust numerical framework for optimizing design against fire-induced shear buckling, addressing limitations in current analytical methods.