Testing of a post-tensioned coupled shear wall structure

A 40%-scale reinforced concrete coupled core wall structure with novel unbonded post-tensioned coupling beams was recently tested under quasi-static reversed-cyclic lateral loading combined with tributary gravity loads. This paper provides an overview of the design, analysis, and testing of this specimen. The specimen represented the most critical bottom three stories of an 8-story prototype structure consisting of two C-shaped wall piers, six post-tensioned coupling beams, tributary post-tensioned slabs at each floor, and the foundation. The less critical upper stories of the prototype structure were simulated analytically to impose lateral forces, axial forces, and overturning moments at the top of the laboratory specimen. Overall, the structure performed as predicted and validated the design approach, which was conducted for a maximum roof drift ratio of 3% for the full 8-story structure. Strength loss during the final cycles of the test was largely caused by the fracture of the vertical reinforcing bars in the wall pier toes at the base. The post-tensioned coupling beams performed well, demonstrating the advantages of the new system.