Recent Advances in Seismic Retrofit of RC Frames

This paper reviews the results of some recent works conducted by the author on newmethods of retrofitting the RC frames. On the local retrofit of RC members, it includes thework on the application of a new high performance fibre-reinforced cementitious composite material. The composite can be applied either as a wet mix to the desired thickness or attached as precast sheets or strips to the face of the member using a suitable epoxy adhesive. The suitability of this technique of member retrofit to enhance the strength and ductility of the retrofitted member compared with other methods of local retrofit, such as steel plates and FRP laminates, is discussed. Other works reviewed in this paper include those carried out recently on global retrofit of RC frames using direct internal steel bracing. Results of inelastic pushover tests on scaled models of ductile RC frames, directly braced by steel X and knee braces are presented which indicate that such bracings can increase the yield and strength capacities and reduce the global displacements of the frames to the desired levels. Also, the results of direct tensile tests on three full scale models of three different types of brace/RC frame connections are presented. Finally, the values of seismic behaviour factor, R, for this type of brace/frame system, evaluated from inelastic pushover analysis of dual systems of different heights and configurations are presented.