Numerical investigation and design rules for flexural capacities of H-section high-strength steel beams with and without web openings

This paper presents a finite-element (FE) investigation on the flexural capacities of H-section high-strength steel beams with web openings. A non-linear finite-element model (FEM) was developed for H-section high-strength steel beams with web openings, which included initial geometric imperfections. The FEMs were validated against the test results available in the literature for H-section high-strength steel beams with web openings. The validated FEMs were then used to conduct a parametric study comprising 180 FEMs to investigate the effects of different cross-sections, the opening diameter, the number of opening and the type of loadings on flexural capacities of H-section high-strength steel beams. The flexural capacities predicted from the finite-element analysis (FEA) were also used to study the performance of the current design guidelines for steel structures. A comparison of numerical strengths and design strengths found that the American National Standard (AISC) is over-conservative by as much as 61%, whereas the North American Specification (NAS) and Chinese Code (CC) are conservative by 34% on average, when predicting the flexural capacities of H-section high-strength steel beams with web openings. In addition, the Steel Design Guide Series 2 (SDGS-2) and Continuous Strength Method (CSM) for cold-formed steel (CFS) members with openings are generally appropriate for H-section high-strength steel beams with web openings subjected to flexural failure. Moreover, the design rules from Direct Strength Method (DSM) were found to be over-conservative by around 40%. Accordingly, this paper proposes modified design equations over the existing design rules of SDGS-2. The proposed design equations have predicted closely the flexural capacities of H-section high-strength steel beams with web openings, being only 1% conservative to the FEA strengths.