School of Civil Engineering, Karunya University, Coimbatore, India.
Recent earthquakes have demonstrated that most of the reinforced concrete structures were severely damaged during earthquakes and they need major repair works. Upgradation to higher seismic zones of several cities and towns in the country has also necessitated in evolving new retrofitting strategies. One of the techniques of strengthening the RC structural members is through external confinement by high strength fiber composites which can significantly enhance the strength and ductility and will result in large energy absorption capacity of structural members. Fiber materials, which are available in the form of sheets, are being used to strengthen a variety of RC elements to enhance the flexural, shear, and axial load carrying capacity of elements. Beam-column joints, being the lateral and vertical load resisting members in RC structures are particularly vulnerable to failures during earthquakes and hence their retrofit is often the key to successful seismic retrofit strategy. The existing reinforced concrete beam-column joints which were designed as per code IS 456:2000 must be strengthened since they do not meet the requirements given in the ductility code IS 13920:1993. In this paper an attempt has been made to study the behavior of reinforced concrete beamcolumn joints retrofitted with Sisal fiber sheets. Six exterior reinforced concrete beam-column joint specimens (control) were cast and tested to failure. Three specimens had reinforcement details as per code IS 456:2000. Remaining three specimens had reinforcement details as per code IS 13920:1993. Various percentages of the load carrying capacity of column were given as axial load in the column. Push and pull load was applied at the free end of the cantilever beam till failure. The failed three beam-column joint specimens have reinforcement details as per code IS 456:2000 were retrofitted by removing the concrete in the joint portion and recasting with concrete of same grade and subsequently wrapped with sisal fiber sheets to strengthen the specimens. The performance of the retrofitted beam-column joints was compared with the control beam-column joint specimens and the results are presented in this paper.
Beam-column joint, Retrofitting, Sisal fiber
