Concrete Jacketing using Diagonal Collars for Exterior Beam Column Joints

Abstract

The extensive and irreparable damages to concrete buildings during past earthquakes have led to concern about the behaviour of joints. Most of the seismic codes are being revised to incorporate measures to improve ductility such as confinement of joints by closely spaced stirrups and providing sufficient development length for beam reinforcement. All these led to congestion of steel in the joint region causing construction difficulties. Research shows that despite improvement in provisions of codes, the seismic performances of joint regions are not satisfactory and failed to shift the potential failure zone away from the joint region. In this context, retrofitting of ductile beam-column joints can improve seismic behaviour. The present study concentrates on the performance evaluation of ductile exterior beam-column joints and their retrofitting by modifying the detailing of RC jacketing reinforcement. One- third scale specimens of joint (exterior) designed and detailed by incorporating proposed amendments to IS 1893(Part 1): 2002 and IS 13920: 2016 were considered for the present study. Test specimens were cast with different reinforcement patterns for jacketing. Experimental results indicate that the performance of the jacketed specimen with proposed detailing of reinforcement enhanced considerably than the jacketed specimen with conventional detailing of jacketing concrete.