Development of Strut Model for Evaluating Shear Capacity of Beams With Elongated Circular Web Openings

There are a number of reasons for considering web openings in steel structures with I-sections. Design of these structural members is always a practical challenge in steel construction. There are several design methods available in the literature for design of these components. Most of these methods rely on the moment-shear-axial interaction curves. However, the preliminary studies have shown that the real performance of these reduced sections is in the form of diagonal struts. The objective of this study is to present a new model based on the tensile and compressive action of diagonal struts at reduced web region to calculate shear strength of the perforated section.For this purpose, the geometry and dimensions of the diagonal struts are described and the shear strength of reduced section is calculated accordingly. To assess the accuracy of proposed geometry and dimensions for diagonal struts, a topology optimization is conducted for two finite element models and results are compared to the proposed values based on which a good agreement is found between optimized and proposed geometries. Next, design curves are presented for calculation of shear strength followed by comparison of proposed model and its predictions with the ones obtained from numerical analysis. Comparing the predictions of the proposed model with the results of 120 finite element samples, the absolute mean error and standard deviation of absolute error were calculated to be 6% and 3.7%, respectively. This comparison shows that, although the presented model is simple and easy to use, it has acceptable accuracy and can be utilized for calculation of shear strength in perforated steel I-beams.