Development of design guideline for seismic retrofitting of RC beam - column joints usıng CFRP materials

Abstract

For the past several decades, seismic designs of structures have been continuously upgraded to meet higher seismic resistance standards. In addition, the researchers have also focused on the seismic behavior of beam-column joints since they were inadequately detailed and ultimately became the weakest links in the lateral load resisting systems of reinforced concrete (RC)-framed structures as per past - earthquake experiences. Effects of various parameters on seismic behavior of these weak links have been investigated through numerous experimental studies performed on typical beam-column joint subassemblies that have been designed to represent interior or exterior joints in a typical RC frame according to pre 1970s design and construction practice. Well-established knowledge of RC joint shear behavior is necessary since severe damage within a joint panel may trigger deterioration of the overall performance of RC beam-column connections or frames. To enhance the seismic performance of such joint systems with insufficient reinforcement details, several strengthening techniques have been proposed by various researchers. In this analytical research, previous strengthening techniques were studied using carbon fiber reinforced polymers (CFRP) to retrofit the deficient beam-column joints and the effects were investigated on the specimens having structural deficiencies. CFRP retrofitting method was investigated as a design guideline with limitations, checking, calculations in order to be a suitable and efficient choice. The column versus beam moment strength ratio, confinement and axial load effects, moment demand versus moment capacity ratio for joints are studied for all types of beam-column joints in order to overcome shear force demanded by applied lateral earthquake loading.