This paper presents recommended seismic design and detailing guidelines for special unbonded posttensioned “hybrid�? precast concrete shear walls, including a full-scale worked design example and supporting experimental evidence from six 0.4-scale test specimens. Hybrid precast concrete walls use a combination of mild steel bars (Grade 400 [Grade 60]) and high-strength unbonded posttensioning steel strands for lateral resistance across horizontal joints. The mild steel bars are designed to yield in tension and compression, providing energy dissipation. The unbonded posttensioning strands provide self-centering capability to reduce the residual lateral displacements of the structure after a large earthquake. The proposed design guidelines are aimed to allow practicing engineers and precast concrete producers to design American Concrete Institute–compliant hybrid shear walls with predictable and reliable seismic behavior. Ultimately, the results from this project support the U.S. code approval of the hybrid precast concrete wall system as a special reinforced concrete shear wall for moderate and high seismic regions.
