Seismic testing and performance of precast high-strength concrete beam-column joints subjected to high axial tension

High-rise buildings are subjected during severe earthquakes and strong winds to intensive large axial and lateral loads, particularly at their lower stories, where the exterior columns experience varying high axial loads. Herein, the seismic performance of two precast high-strength reinforced concrete exterior beam-column joints subjected to different varying high-axial levels is investigated while premature shear failure is generally suspected. High-grade steel bars were used for reinforcement. Splice grout-sleeves and mechanical anchors were used in the columns and beams, respectively. The strength of the concrete was 70 MPa. The maximum axial tension level in columns was 90% of the yield strength of the main bars. Under high axial tension, the tested subassemblies exhibited stable response, good damping characteristics, appropriate lateral force resistance and energy absorption capacity. They performed well within the lateral story drift angle of 3% where the successive failure modes (beam/column flexural yielding followed by joint shear failure) confirmed the appropriateness of the design equations in AIJ and ACI regulations. Furthermore, the use of mechanical anchors proved to be very effective and no sign of concrete crushing (pushing toward the exterior face of the joint) was observed within the lateral story drift angle of 2%.