Corner beam-column joints seismic retrofitting with high performance fiber-reinforced concrete jacketing

The experimental results on full-scale corner beam-column joints tests are presented herein, with the aim of studying the effectiveness in strengthening existing RC existing structures of the application of a HPFRC jacket. The specimens subassemblies have been designed with structural deficiencies typical of the Italian construction practice of the 60’s-70’s: absence of any capacity design principle, use of smooth bars, inadequate reinforcement detailing, such as total lack of stirrups in the joint panel and hook-ended anchorage. Both unretrofitted and retrofitted specimens have been tested under simulated seismic loads. The results underline the significant vulnerability of the joint panel region and the critical role of the slippage phenomena related to the use of smooth bars and show that, with the application of a HPFRC jacket, it is possible to increase the bearing capacity of the columns, reaching also an adequate level of ductility and strength of the beam column joints.