Seismic performance of an innovative elliptical tube web reduced beam section connection

This study introduces an innovative corrugated web reduced beam section (RBS) connection, referred to as the elliptical tube web RBS (ETW-RBS) connection. In this design, the flat web of the beam is removed within a short distance from the column face and replaced with an elliptical tube. Due to the lower axial stiffness of the elliptical tube compared to the flat web, the flexural strength of the beam in the reduced section is decreased, facilitating the formation of a plastic hinge in this region. Additionally, the elliptical tube enhances the lateraltorsional stability of the beam within the reduced section. The seismic performance of the proposed connection is assessed using nonlinear finite element analysis (FEA). The numerical model is validated against experimental results from the literature, followed by an analysis of several models under cyclic loading to investigate the behavior of the proposed connection. Comparisons are made with the conventional radius cut RBS (RC-RBS) and tubular web RBS (TW-RBS) connections. Moreover, the influence of the distance between the column face and the start of the reduced section on the performance of the connection is examined. The findings indicate that the proposed connection exhibits stable hysteretic behavior, improved ductility, and reduced strength degradation compared to the RC-RBS connection. Furthermore, the extended length of the reduced section in the ETW-RBS connection, relative to the TW-RBS connection, reduces the maximum equivalent plastic strain, delaying failure due to low-cycle fatigue.