Numerical investigation on web of steel I-beam with closed top flange under patch loading

This paper studies the failure of steel beams' webs and suggests strengthening systems. The study investigates the patch-loading resistance of I-girders with closed top-flange configurations (triangle or rectangle) formed by welding stiffener plates or angles between the web and flange edge. Non-linear finite element models are developed and validated to examine the ultimate structural response and failure modes, followed by a parametric study addressing the interaction between stiffener thickness, web thickness, and relative stiffener depth, all under variable patch loading lengths. Compact stiffeners provide a greater increase in girder strength, particularly for thin webs and short patch load lengths, whereas slender stiffeners are less effective. Increasing stiffener depth and thickness enhances load redistribution and delays web deformation. Triangular configurations generally provide higher resistance than rectangular configurations for the same added steel area. EN can calculate the web capacity for the models in the study, but to conservative side. Recommendation is to apply the actual stiffener stiffness in EN avoiding the limitation given in code. Overall, the findings provide practical guidance for selecting stiffener dimensions and closed-flange configurations to improve web resistance under patch-loading.