NUMERICAL INVESTIGATION FOR SEISMIC PERFORMANCE OF SQUARE BRIDGE CONCRETE COLUMNS CONFINED WITH COMBINED STEEL AND FRP TIES

抄録

Majority failure of ductile behavior of the tested flexural bridge columns was buckling of longitudinal bars, which occurred after yielding of the perimeter ties. Increasing the transverse reinforcement specified in design codes for bridge columns in plastic hinge zone to confine and prevent premature buckling of longitudinal bars for column deformation ductility has a limit due to yielding of reinforcement steel ties. Types of fiber-reinforced polymer (FRP) have the strength and yield (rupture) strain higher than steel-reinforcement leads to enhance the confinement. Recently, using FRP ties has been spread especially in the destructive environment to enhance the deformation ductility. This paper presents a numerical investigation model to predicate the behavior of square bridge column confined using a combination of steel and rectangular closed FRP ties in the plastic hinge zone subjected to reversed lateral cyclic load. Results showed enhancement of columns’ deformation ductility and indicated that closed FRP ties provide effective confinement resulting in delay bars’ buckling and increasing the drift ratio more than 16.6%.