Behaviour of reinforced concrete frames rehabilitated with concentric steel bracing

The seismic performance of low-rise nonductile reinforced concrete (RC) buildings rehabilitated using concentric steel bracing is investigated. A three-story building was analysed using various ground motion records. The effectiveness of the steel bracing in rehabilitating the three-story building was examined. The effect of the distribution of the steel bracing along the height of the RC frames on the seismic performance of the rehabilitated building was studied. The behaviour of the nonductile RC frame members is represented using a beam-column element capable of modelling the strength softening and the effects of the axial force on the yield moment and the deformation capacities at peak strength of these members. The performance of the building is evaluated in terms of global and story drifts and damage indices. A simplified approach is proposed for selecting the proper brace distribution.Key words: reinforced concrete, frame, nonductile, rehabilitation, concentric steel brace.