Coupling of Concrete Walls Using Post-Tensioned Precast Concrete Beams

This paper describes an analytical investigation on the nonlinear behavior of post-tensioned precast concrete beams to couple reinforced concrete walls. Different from conventional systems that use monolithic cast-in-place reinforced concrete coupling beams or embedded steel coupling beams, the nonlinear behavior of post-tensioned precast concrete coupling beams is governed by the opening of gaps at the beam ends. Steel top and seat angles are used at the beam-to-wall connections to yield and dissipate energy in the event of a large earthquake. Two types of analytical models are developed using the DRAIN-2DX and ABAQUS programs for verification of the results and more detailed evaluation of the expected behavior. Nonlinear reversed cyclic lateral load analyses of four coupling beam subassemblies are conducted. The main parameters investigated are the beam depth, the area of the post-tensioning steel, and the size of the top and seat angles. The results indicate that post-tensioned precast concrete coupling beams possess stable behavior through large rotations, significant self-centering capability due to the post-tensioning force, and significant energy dissipation provided by the yielding of the top and seat angles.