Studies on the behavior of retrofitted RCC beam column joints

Abstract

In the last few decades earthquakes have struck different parts of the world. Recent earthquakes have demonstrated that most of the reinforced concrete structures specially the beam-column joints are vulnerable during earthquakes. The basic requirement of design is that the joint must be stronger than the adjoining hinging members, usually the beams or columns. The existing reinforced concrete beam-column joints which are designed as per code IS 456:2000 do not meet the requirements given in the ductility code IS 13920:1993. Hence the beam-column joints that are not designed as per the ductility code may not perform well when subjected to seismic forces. They must be strengthened in order to improve there performance during earthquakes. Until 1990, concrete jacketing and steel jacketing were the two common methods adopted for strengthening the deficient reinforced concrete beam-column joints. Concrete jacketing increases the cross sectional area and self-weight of the structure. Steel jackets are poor in resisting weather attacks. Both methods are labour intensive and difficult to implement at the site. A new technique for strengthening the reinforced concrete structural members is through confinement with an external fiber reinforced polymer sheets. The effectiveness of the strengthening has to be evaluated experimentally. An attempt has been made to carryout an experimental investigation to compare the performance of beam-column joints that are designed as per code IS 456:2000 with that of beam-column joints detailed as per the code IS 13920:1993 for various grade of concrete and various axial loads on column to find out the deficiencies of the joints detailed as per code IS 456:2000. An experimental investigation has been carried out under static load and reversal load to find the load carrying capacity and energy absorption capacity of reinforced concrete beam-column joint specimens that are detailed as per code IS 456:2000 and retrofitted with various fiber reinforced polymer sheets such as glass fiber ....