SEISMIC PERFORMANCE OF UNBONDED POST-TENSIONED PRECAST CONCRETE BEAM-COLUMN FRAME BUILDINGS WITH BUCKLING-RESTRAINED KNEE BRACES

Abstract

Based on previous earthquakes, it was discovered that precast concrete beam-column systems mostly have weaknesses at the beam-column joints because precast concrete joints tend to have less strength, stiffness and toughness than cast-in-place structures. This study presents an alternative system of precast concrete beam-column structure that utilizes prestressed steel reinforcement and buckling-restrained knee braces (BRKBs). In this study, the exterior beam-column subassemblies were investigated using a quasi-static reversed cyclic loading test to simulate seismic load. The behaviors of three beam-column joint specimens were studied in this study: 1) the cast-in-place beam-column joint 2) the unbonded post-tensioned precast beamcolumn joint, and 3) unbonded post-tensioned precast beam-column joint with the buckling-restrained knee brace (BRKB) installed around the beam-column joint's corner. The test considered damage patterns, force-drift relationship, strength, and energy dissipation. The tests revealed that reinforcing the structure with a buckling-restrained knee brace (BRKB) makes it ductile, with lateral force resistance and energy dissipation similar to the cast-in-place specimen.