Title: Behavior of Beam Column Joints Using High-Strength Materials

Author(s): S. Sugano, T. Nagashima, H. Kimura, and A. Ichikawa

Publication: Symposium Paper

Volume: 123

Issue:

Appears on pages(s): 359-378

Keywords: beams (supports); columns (supports); cyclic loads; high-strength concretes; high-strength steels; joints (junctions); reinforced concrete; shear properties; tests; Structural Research

DOI: 10.14359/2866

Date: 1/1/1991

Abstract:
Cyclic loading tests of eight half-scale interior beam-column subassemblages using high-strength materials were carried out to investigate their seismic behavior under high joint shear stress vn ranging from 140 to 200 kg/cmý. Concretes with three nominal compressive strengths; 400, 600, and 800 kg/cmý was used. High-strength reinforcing bars with a yield strength of 4000 and 6000 kg/cmý were provided as beam longitudinal reinforcement. Reinforcing bars with a yield strength of 8700 kg/cmý were used for joint transverse reinforcement. To prevent premature shear failure in joints and significant slippage of beam bars through joints, four different types of joint detail were planned. They included high-strength bars for joint reinforcement, anchor plates attached to beam longitudinal bars in the joint, relocation of beam plastic hinges away from the joint, and joint reinforcement using steel plates. The beam-column joints using high-strength concrete of 600 kg/cmý or higher showed ductile behavior up to 5 percent story drift, even under conditions of high join-shear stress. No significant bar slippage or bond deterioration was observed, including the joints using high-strength beam main bars. The high-strength transverse reinforcement worked effectively as joint reinforcement, as indicated by considerably high strains measured in joint hoops. The relocation of beam plastic hinges away from the joint reduced damage of the beam-column joint. Based on the test results, guidelines for design of such reinforced concrete beam-column joints are presented.