Seismic Resistance of Reinforced Concrete Beam-Column Joints

Full size cast-in-place reinforced concrete beam-column joints representing a critical portion of a multistory building were tested under simulated earthquake loading. Six of the specimens tested represented an exterior joint unconfined by spandrel beams. A seventh specimen had short unloaded spandrels on each side of the joint. Test variables were column size, column axial load, and amount of joint lateral reinforcement. Reversible elastic and plastic load cycles were applied to each specimen to simulate earthquake loads. Suitability of recommended reinforcing details for use in earthquake resistant design was verified by test results. Specifically, closed rectangular hoops surrounding the joint were shown to be essestial in developing ductility and maintaining strength of isolated joints in structural frames. Energy absorption required in building frames subjected to earthquakes was demonstrated to be amply provided by a properly designed reinforced concrete frame.