Cyclic Testing of Replaceable Steel Coupling Beams with Reduced Beam Sections and Moment End-Plate Connections

Abstract

Coupled walls are a common lateral load resisting system for buildings located in seismic regions. Coupling beams create a ductile link between walls that increase the structure’s resistance to lateral forces and its ability to dissipate seismic energy. During a major seismic event, coupling beams dissipate energy by yielding and acting as a fuse. Replaceable steel coupling beams are an alternative to conventionally and diagonally-reinforced concrete coupling beams and offer the advantage of improved constructability and post-earthquake reparability. Previous studies on replaceable steel coupling beams have focused on shear yielding beams, while this study focused on flexure-yielding beams. Five two-third-scaled, cantilever steel coupling beams with reduced beam sections (RBSs) were tested under fully reversed cyclic loading. The primary test variables were parallel or single steel coupling beams, RBS cut geometry, and moment end-plate to embedded plate wall connection. Coupling beams with and without RBS cuts had deformation capacities of 8% or greater and 6%, respectively. Using RBS cuts within the parameters of AISC 358-16 resulted in the largest ductility. The moment end-plate to embedded plate connection was determined to have a significant effect on the beam stiffness.