High-Strength Concrete Interior Beam-Column Joints with High-Yield-Strength Steel Reinforcements

Abstract

This study presents the experimental and analytical investigations carried out on high-strength concrete beam-column joints with Grade 700 longitudinal bars in beams and columns. Seven full-scale interior RC beam-column joints with various reinforcement detailing were designed according to the specific seismic provisions of current building codes. Test specimen variables included concrete compressive strength, reinforcement yield strength, and axial compression loading level. The test specimens were subjected to constant column axial loading and quasi-static lateral load reversals. The performance of each test assembly was examined in terms of cracking patterns, lateral loading capacity, reinforcement strain profiles, secant stiffness, energy dissipation capacity, joint shear strength, and bond performance. All specimens displayed ductile failure mode and it is concluded that the use of high-strength concrete and applied axial compression loading can improve specimen bond conditions. Parametric studies via finite-element analysis were performed to examine the influence of various parameters on the strength, bond condition, and energy dissipation capacity of the specimens. In addition, a backbone curve model for the shear behavior of the joints is proposed. An explanation for the observed cracking pattern and further analytical investigation on the joint shear capacity of the specimens is presented.