Seismic behavior of eccentric new RCS joints with through columns

Abstract

Architectural requirements often result in beam-column joints with eccentrically framing beams. However, the fabrication of eccentric through beam-type reinforced concrete column and steel beam (RCS) joint is extremely complex due to the presence of column longitudinal reinforcement and joint confinement reinforcement. To mitigate the constructability issues associated with through-beam type RCS eccentric joints, the current study proposed a through-column type New RCS joint. The proposed New RCS joint used joint cover plates and continuity plates as additional attachments while eliminating the need for joint confinement reinforcement. Two large-scale beam column subassembly specimens were tested to evaluate the seismic behavior. Both specimens had high-strength reinforced concrete columns (New RC columns) with a design concrete grade of 84 MPa and steel reinforcement of specified yield stress 690 MPa. The experimental results revealed the asymmetric shear stress development in the joint cover plates due to joint eccentricity. Based on experimental observations, a joint shear force-deformation model was presented, which was able to capture the joint shear response with reasonable accuracy. Finally, simplified expressions were presented, which were able to provide reliable estimates of joint shear strength, which is suitable for design purposes.