Experimental and Numerical Investigation of Bare and Strengthened Wide-Flange Sections Subject to Near-Field Blast Loading

When a wide-flange section is exposed to close-in detonation, local and global deformation modes are developed due to a complex nonuniform pressure environment. The local deformation includes local distortion and rotation of the flanges, as well as deformation of the web, or even breaching near the web/flange junction. Experimental studies are presented to investigate the response of wide-flange sections to close-in detonations with and without stiffener plates and loaded about their weak and strong bending axes. The effectiveness of the stiffeners in mitigating damage is studied, and although they do have a positive effect, in some cases, the stiffeners do not contribute to the member resistance. Numerical models, validated against the test results, are used for a parametric study on the effect of the angle of incidence between the charge and the section, and the web-to-flange thickness ratio. It is found that a member needs to be analyzed for loading directions between the weak and strong bending axes to account for the maximum possible flange distortion. The thickness of the flange is irrelevant for the local web deformation but important for the global behavior of the member.