Structural Response of Thin-Web Beams to Various Web Opening Retrofit Techniques

Abstract

A novel retrofitting method was tested to open steel girder webs. As no standard covers these procedures, this study examined the effect of mid-span apertures on AISC-designed narrow I-beams. Ten specimens with 1.8m length, 0.8m height, and 0.3m flange width were examined, with four simulated in ANSYS to validate results and explore parametric effects (yield stress and web thickness). Openings lower strength by 43% and increase deflection by 10%. Two retrofitting options involve patch plates welded to one or both sides of the aperture. Patch plate retrofitting removes 8% deflection and restores 26% strength. As an alternate retrofitting option, adding two stiffeners to the opening sides increases strength by 73% and reduces deflections by 68%. Patches and stiffeners work best together, improving strength by 123% and lowering deflection by 89%. Testing the modified specimens demonstrated that patch plate welding to treat steel web openings works well. Instead of treating the opening, stiffeners on the side improve girder behaviour. Experimental and finite element analysis results match at different levels. Additionally, numerical stress findings provide a satisfactory estimate of beam element stress.