Hybrid Post-Tensioned Precast Concrete Walls for Use in Seismic Regions

Recent research has shown that post-tensioned precast concrete lateral load resisting walls that do not emulate the behavior of monolithic cast-in-place reinforced concrete walls have desirable seismic characteristics such as a self-centering capability and an ability to undergo nonlinear lateral displacements with little damage. The biggest disadvantage of these walls under earthquake loading is an increase in the lateral displacements as a result of small energy dissipation. This paper investigates a hybrid precast wall system that uses mild steel reinforcement in addition to the post-tensioning steel for flexural strength and inelastic energy dissipation. An analytical parametric study is conducted to compare the expected seismic behavior of a series of prototype walls with different amounts of mild steel and post-tensioning steel. Nonlinear dynamic time history analyses of the walls indicate that the use of mild steel reinforcement results in a considerable reduction in the lateral displacements of the walls under earthquake loading, particularly for walls in regions of high seismicity and with shorter periods of vibration. The results of these analyses are used to present preliminary design implications for the use of hybrid post-tensioned precast walls in seismic regions.