Seismic tests of beam-to-column connections in a precast concrete frame

Two full-scale beam-to-column connections in a precast concrete frame were tested under uni-directional and bi-directional cyclic loading that simulated earthquake-type motions. Variables included the detailing used at the joint to achieve structural continuity of the beam reinforcement, and the type of framing (whether two-dimensional or three-dimensional). The most relevant feature of the connection is that conventional mild steel reinforcing bars or prestressing strands, rather than welding or special bolts, were used to achieve beam continuity. Specimen design followed the strong-column-weak-beam concept. Beam reinforcement was purposely designed and detailed to develop hinges at the joint faces and to impose large inelastic shear force demands into the joint. During specimen fabrication, the joint details enabled ease and speed of construction. As expected, the joint controlled the specimen failure. In general, the performance of both beam-to-column connections was satisfactory. Joint strength was 80 percent of that expected for monolithic reinforced concrete construction. Specimen behavior was ductile due to hoop yielding and bar pullout, while strength was nearly constant up to drifts of 3.5 percent.