Seismic Performance of 3Dimensional Interior Reinforced Concrete Beam-Column Joints Strengthened with CFRP sheets

Abstract

Abstract Recent studies on flexural/shear strengthening of reinforced concrete beam-column joints with FRP composites have mainly focused on rehabilitation of 2Dimensional connections regardless of the effects of perpendicular beams. Present experimental study investigates the behavior of 3Dimensional interior RC joint under simultaneous lateral reversed cyclic loading in one direction and gravity loads in the orthogonal orientation. Three full-scale specimens were tested including one un-strengthened and two strengthened ones. Strengthening was performed using 1 and 3 L-shape layers of CFRP composite sheets at top and bottom faces of the joints, 1- and 4-strip wrapping layers at beams,1 and 2 full wrapping layers at column and conducting the method of externally bonded reinforcement on grooves (EBROG) to prohibit the premature FRP debonding. Results for failure mode, flexural capacity, ductility factor, energy dissipation and stiffness degradation indicate improvements in seismic behavior of flexural strengthened joints, where specially the increase in strength was reported 9 and 23 percents for two strengthened specimens. To evaluate the reported information, “sectional analysis theory” has been adopted for numerical prediction of maximum flexural capacity for 3D interior RC joints. Results are reliably compatible with the test results and observations as well. Comparing the reported values and numerical ones, the EBROG method appears successfully efficient in preventing FRP debonding and providing the maximum expected contribution of FRP in improving the seismic behavior.