Procedures to rehabilitate extremely damaged concrete members using innovative materials and devices

Abstract

Using innovative materials or devices in techniques for strengthening or repair of RC concrete members may provide interesting alternatives for structural engineers. Laboratory tests were conducted on full scale reinforced concrete columns and a masonry wall that suffered severe damage. Carbon Fiber Reinforced Polymer - CFRP sheets and anchors were used to improve shear capacity or ductility elements. CFRP jacket were installed on column hinge regions while diagonal ties (tension braces) were used on the masonry wall. Mechanical splices were used in columns where concrete crushed and bars buckled by replacing the buckled bars and providing continuity to the longitudinal reinforcement. It was found that performance of the retrofitted members was comparable to that using conventional techniques and the performance was generally better than certain “fast” retrofit procedures reported in the literature. The choice of technique depends on the degree of damage, the cost of replacement, and performance required.

Having the results of cyclic load tests of rehabilitated concrete members, envelope or backbone curves were obtained following the ASCE41-07 and proposed ASCE41-13 procedures. The backbone curves were used to develop behavioral models that can be used in the analysis and design of those types of concrete members and retrofit procedures. The inclusion of the behavioral models into current Performance Based Seismic Design procedures for strengthening of existing or repaired damaged buildings is proposed.