Cyclic Loading Test for Beam-Column Connections with 600 MPa (87 ksi) Beam Flexural Reinforcing Bars

Abstract

An experimental study was performed to evaluate the seismic performance of beam-column connections using Grade 600 MPa (87.0 ksi) bars for beam flexural reinforcement. Four full-scale interior connections and three exterior connections were tested under cyclic lateral loading. The specimens were designed according to the special seismic provisions in ACI 318-11. The column depth-beam reinforcing bar diameter ratios h(c)/d(b) were 20.5 to 25.0. The structural performance of the specimens with 600 MPa (87.0 ksi) D22 (diameter = 22 mm [0.87 in.]) and D25 (diameter = 25 mm [0.98 in.]) bars were directly compared with that of the specimen with 400 MPa (58.0 ksi) D25 bars. In the case of the interior connections, the load-carrying capacity and maximum deformation were close to those of the specimen with 400 MPa (58.0 ksi) bars. On the other hand, the energy dissipation capacity of the specimens with 600 MPa (87.0 ksi) bars decreased by a maximum of 25% due to the increased bond-slip at the joints. In the case of the exterior connections, significant bond-slip occurred at the beam bottom bars due to insufficient development length, which decreased the deformation capacity and energy dissipation capacity of the specimens.