Seismic Performance of RC Beam–Column Joints Constructed with Engineered Cementitious Composites

Abstract

This paper presents experimental and analytical investigations carried out on RC beam–column joints incorporating engineered cementitious composite (ECC) material in the beam–column joint region. Six interior and exterior beam–column joints with different reinforcing detailing in the joint cores were designed and tested. Representative column axial loading and quasi-static lateral cyclic loadings were applied. Hysteresis behavior, crack patterns, joint shear stress, energy dissipation capacity, and strain profiles of reinforcements were examined. Results demonstrated ductile failure with flexural plastic hinges generated in the adjacent beams, which indicated an improvement of the joint shear capacity with the application of ECC. An analytical truss model for ECC joints was developed to investigate the joint shear force transfer mechanism. The predicted internal force flow of the ECC joints under seismic action yielded a reasonable correlation with the crack pattern. The effect of the joint transverse reinforcement also was studied based on the analytical model. A parametric study was performed via a validated finite-element analysis. Results indicated that higher column axial loading was detrimental to the performance of the joints, especially above an axial load ratio of 0.3 for joints incorporated with higher strength ECC. In addition, joint transverse reinforcements still needed to be added in some cases to avoid joint shear failure.