Upgrading of nonductile reinforced concrete frame connections

An innovative seismic upgrading technique for existing reinforced concrete frame connections constructed prior to the 1970s using corrugated steel jacketing is proposed and evaluated. Six, one-third scale, reinforced concrete beam-to-column connections were tested under quasi-static cyclic loading to study their seismic performance. The investigated test parameters include the amount of joint and column transverse reinforcement, corrugated steel sheet thicknesses, and jacketing of column only or of both column and beam. Test results demonstrated that existing reinforced concrete frame connections upgraded using corrugated steel jackets performed satisfactorily when subjected to high cyclic load levels. The corrugated steel jacket was found to be an effective system of upgrading as it increases the joint shear strength and the energy dissipation capacity. A method for the design of the corrugated steel jacket thickness and depth of corrugation is formulated.