Seismic behavior of replaceable steel truss coupling beams with buckling restrained webs

• A type of steel truss coupling beam with a buckling restrained web was proposed.
• The effects of configurations of the steel webs on seismic behavior were investigated.
• The proposed coupling beams exhibited excellent energy absorption capacity.
• A modified strip model was developed to predict the strength of a coupling beam.

In order to facilitate the constructability and meanwhile ensure desirable seismic behavior, an innovative type of replaceable steel truss coupling beam with a buckling restrained web was conceived and studied. The buckling restrained steel web is designed and detailed as a fuse and a damper of the beam in which all inelastic deformations and damage are concentrated. Bolted connections between steel webs and beam chords, as well as pin connections between beam chords and adjacent reinforced concrete shear walls, are employed to minimize the post-event repair/replacement difficulties and expenses. To evaluate the seismic behavior, three large scale coupling beam specimens were constructed and tested under cyclic loadings. The effects of some configurations of the steel webs including welded edge stiffeners and slits on the seismic behavior were highlighted. The test results indicate that all three specimens failed in a ductile manner with a concentration of inelastic deformation at steel webs and thus exhibited desirable deformation and energy absorption capacities. The strength and stiffness of the proposed coupling beam can be enhanced by welding edge stiffeners to steel webs while the steel web with slits is susceptive to suffer significant buckling of flexural links, resulting in a relatively lower strength and ductility of the beam. To predict the load carrying capacity of the proposed coupling beam, a modified strip model to account for the beneficial effects of the buckling–bracing provided by precast reinforced concrete panels was developed. The analytical results were compared with the experimental results.