ENHANCEMENT OF SEISMIC BEHAVIOR OF REINFORCED CONCRETE COLUMNS BY CONTROLING BOND BETWEEN CONCRETE AND REINFORCEMENT

An extensive experimental investigation was carried out to examine how controlling the bond of the longitudinal reinforcements can improve seismic performance, such as shear strength and ductility, of RC structures. The tested RC columns under reversed cyclic loading were of six different bond conditions, varying from perfect bond with the use of ordinary deformed bars, to perfect unbond. The results of the experiment revealed that the failure mode at the ultimate state could be changed from shear to flexure by reducing the bond strength of the longitudinal bars. The test results also showed that RC columns reinforced with bond controlled bars had significantly better shear strength and ductility than RC columns reinforced with ordinary bars. The subsequent analytical investigations using 3-D nonlinear finite element method indicated the validity of the suggested analytical model, and revealed the change of stress transfer mechanism inside the RC columns with various bond conditions of longitudinal bars.