Experimental evaluation of a multi-story post-tensioned coupled shear wall structure

This paper discusses the design and experimental evaluation of a novel seismic-resistant reinforced concrete (RC) coupled shear wall system. In this system, the widely-used unbonded post-tensioned floor slab construction method is adapted to couple (i.e., link) two RC wall piers, providing significant performance and construction benefits over conventional RC coupling beams in high seismic regions. Previous experiments of post-tensioned coupled wall structures are limited to floor-level coupling beam subassemblies. The current paper extends the available research to multi-story structures by presenting the design of an 8-story prototype test specimen consisting of two C-shaped shear walls. The design is validated through the testing of a simplified 15% scale specimen in the laboratory. The experimental specimen includes the foundation, the first three floors of the shear walls, and the associated coupling beams. The upper stories of the building are simulated with hydraulic jacks that supply the appropriate bending moment, shear, and axial forces at the top of the laboratory structure. This paper compares the measured load displacement response of the laboratory structure with predictions from design models. Experimental and design predictions of several key behavior parameters are shown to match well. Future work involves the construction and testing of large scale (40%) specimens to validate the approach. Ultimately, the measured information from the test specimens will be used in the development of validated design procedures and modeling/prediction tools for multi-story post-tensioned coupled wall structures.