Ultimate Strength of Beams with Rectangular Holes

Abstract

An experimental and analytical investigation of the behavior and ultimate strength of wide-flange beams having unreinforced rectangular web holes is summarized. Rectangular holes were chosen because of their prevalence in practice. Four 10-ft long 16WF36 simply supported beams were tested with one or two concentrated loads. Results showed that as the load on the beam with a web hole increases, the first yielding in the beam in the vicinity of the hole occurs at the corners of the hole as a result of stress concentration at the corner. With further increase of the load, yielding spreads through the web and through the flanges. The ultimate load can be predicted by a lower-bound solution in which strain hardening is neglected. The ultimate loads for the test beams averaged 19% below the experimental loads. The allowable design loads indicate that the plastic-design analysis gives the greater allowable load, except at very high moment-shear ratios.