Studies on the Performance of RC Beam–Column Joints Strengthened Using Different Composite Materials

Abstract

Many reinforced concrete structures in our country are in a deteriorated or distressed state. Hence strengthening such structures or reducing the load limit on them is becoming necessary to extend their service life. Beam–column joint is the crucial zone in a reinforced concrete moment resisting frame since it is subjected to large forces during severe ground shaking. In the present study, an attempt has been made to determine the cost-effective composite material and optimum number of layers of composite material for strengthening beam–column joints. Specimens were strengthened using ferrocement, glass fibre reinforced polymer (GFRP) and carbon fibre reinforced polymer (CFRP) and studied their behaviour under static as well as cyclic loading. It was found that the rotation at ultimate moment of all the strengthened beam–column joints were greater than that of the control specimens. The specimens strengthened with more number of layers of strengthening material showed better moment–rotation characteristics. The joints strengthened using GFRP showed better performance in terms of ultimate load, moment rotation characteristics, ductility, energy absorption capacity and strength-to-cost ratio, when compared to that of the specimens strengthened with other composite materials. However, CFRP strengthened specimens showed good ductility and better cracking characteristics and prevented the failure at the joint.