Structural behavior of beam column joint retrofitted using carbon fiber reinforced polymer

Abstract

Beam column joints are one of the most critical components of reinforced concrete (RC) structures since it is subjected to large forces during severe ground shaking. The present study comprises four exterior beam-column joint specimens having different reinforcement arrangements detailed as per IS 13920: 1993, tested under reversed cyclic loading up_to failure. The test was force-controlled and the specimen was loaded by increasing the load level during each cycle. The load was applied forward cyclic and reverse cyclic and deflection, were measured from every 5kN by using a linear variable digital transducer (LVDT) with the digital arrangement. The deflection was measured at the loading point and at the centre of the beam.  Damaged specimens were repaired and retrofitted with carbon fibre reinforced polymer (CFRP) to prevent shear damage and strength deterioration and to achieve a more ductile response. Retrofitted specimens were subjected to similar cyclic loading. Results for displacement were obtained. Hysteresis behaviour of non-retrofitted and retrofitted specimens were studied with respect to ultimate load, maximum displacement, energy dissipation capacity, stiffness degradation and general failure pattern. The comparisons showed that CFRP sheets improved the shear resistance of the joint and increased its energy dissipation capacity.  Retrofitting makes the joint so strong that failure is directed towards the beams as it helps the structure in energy dissipation through plastic hinge formation in the beam.