Vierendeel Bending Study of Perforated Steel Beams with Various Novel Web Opening Shapes through Nonlinear Finite-Element Analyses

The Vierendeel mechanism is always critical in perforated steel beams with single large web openings, where global shear forces and Vierendeel moments coexist. Thus far, the main parameters that affect the structural behavior of such beams are the depth of the web opening, the critical opening length of the top T-section, and the web opening area. A comprehensive finite-element (FE) study of four sizes of perforated steel sections with three different sizes of 11 standard and novel nonstandard web opening shapes was undertaken, and their primary structural characteristics are presented in detail to provide a simple design method for general practice. The different geometric parameters were isolated and studied to understand the significance of their effects and in turn advance the knowledge on the performance of perforated steel beams. An elaborate FE model was established, with both material and geometrical nonlinearity, allowing load redistribution across the web openings and formation of the Vierendeel mechanism. The reduction of the global shear capacities, because of incorporation of the local Vierendeel moments acting on the top and bottom T-sections, was obtained directly from the FE analysis. Following that, a comparison of the global shear-moment ($(V/M)$) interaction curves of the steel sections with various web opening shapes and sizes was established, and empirical generalized $V/M$ interaction curves were developed. Moreover, the accurate position of the plastic hinges was determined together with the critical opening length and the Vierendeel parameter. This work has shown that the shape of the web opening can also significantly affect the structural behavior of perforated beams, as opposed to the equivalent rectangular shape predominately used so far. In addition, the effect of the position of the web opening along the length of the perforated beam was revealed. The importance of the parameters that affects the structural performance of such beams is illustrated. The thorough examination of the computational results has led to useful conclusions and an elliptical form of a web opening is proposed for further study. The outcomes are considered relevant for practical applications.