Analytical and numerical investigation of the seismic behavior of tubular web reduced beam section connections

The reduced beam section (RBS) connections in steel structures are widely used to achieve sufficient ductility and avoid creating brittle failures in moment‐resisting frames. Compared to other types of connections, conventional RBS connections have the potential to reduce moment capacity and induce larger lateral deformation in the structure. In order to resolve this problem, novel forms of RBS connections have been proposed in recent years, such as tubular web RBS connections, which have shown a desirable performance under various loading conditions in previous studies. Therefore, this study conducted an analytic and numerical investigation of this connection under seismic loading. In this regard, the first step is to introduce the analytic equations related to the structural properties and stability of the reduced beam with the tubular web. Using these equations, a comprehensive procedure for the design of the tubular web RBS connections is presented. After that, a numerical model of the tubular web RBS connections is created and then analyzed under cyclic loading using the finite element method in ABAQUS software. Based on the results of this simulation, the suggested connection meets the criteria of valid international standards and can be used in the special moment‐resisting frame. In order to assess the impact of using the proposed connection in moment‐resisting frames, the performance of two 2D moment‐resisting frames with this connection is studied. This study shows that the maximum percentage increase in relative displacement caused by using tubular web RBS connections is 1.68%, whereas this figure rises to 10.6% when conventional RBS connections are used. Therefore, the designers can use tubular web RBS connections instead of conventional RBS connections to increase the lateral stability of the structure and control its lateral deflection due to the seismic loadings without having to increase the dimensions of the frame elements.