Seismic performance of bending‐type frictional steel truss coupling beams

Abstract

AbstractTraditional coupling beams, once seismically damaged, are very difficult to be repaired. Recent studies developed new coupling beams by introducing mid‐span dampers. The shear deformation is concentrated in the damper, thus protecting the primary concrete members. However, the concentrated shear deformation will result in slab damage. This paper proposes a novel bending‐type steel truss coupling beam (BFTCB) that adapts to slab bending deformation. The steel truss is securely connected to the slab at the top chord. It remains elastic during an earthquake, while inelastic deformation is confined to friction dampers equipped on both ends of the bottom chord. Friction dampers render the coupling beam damage‐reparability, which can be rapidly repaired by retightening or replacing the bolts after a major earthquake. The main body of wall piers sustain negligible damage and can remain in service; thus, they can be exposed to more earthquakes during the lifetime of the building. Unlike solid web sections, the truss configuration decouples bending and shear demands, as well as stiffness and strength, which improves the design flexibility. Quasi‐static tests were conducted to validate the design concepts and confirm the replaceability of the BFTCB. The BFTCB displayed full and stable hysteretic behavior. The theoretical formula for the strength and stiffness of the BFTCB afforded acceptable accuracy. The proposed BFTCB shows promising potential for resilience‐oriented high‐performance structures.