Steel-Reinforced Concrete Coupling Beams. I: Testing

Abstract

Structural steel-reinforced concrete (SRC) coupling beams are an alternative to conventional and diagonal rebar-reinforced concrete coupling beams. To address gaps in previous testing that was used to develop design recommendations, four large-scale, flexure-yielding, cantilever SRC coupling beams were embedded, without inclusion of auxiliary transfer bars and bearing plates, into reinforced concrete structural walls. Beams were tested by applying quasi-static, reversed-cyclic shear loading to the coupling beam, and moment and shear to the top of the wall to create cyclic tension and compression fields across the embedment region. The primary test variables were the structural steel section embedment length, beam span length (aspect ratio), quantities of wall boundary longitudinal and transverse reinforcement, and applied wall loading (moment, shear, and axial load). Favorable performance, characterized by minimal pinching and asymmetry in the load-deformation response and concentration of damage at the beam–wall interface, was associated with long embedment length, moderate-to-light wall demands, and heavy wall boundary reinforcement. Reduced embedment length, large wall demands, and light wall boundary reinforcement led to reduced performance, with increased pinching, asymmetry, and cyclic degradation evident in the load-deformation response and significant damage in the embedment region.