Simplified Seismic Design Approach for Friction-Damped Unbonded Post-Tensioned Precast Concrete Walls

This paper addresses the seismic design of unbonded post-tensioned precast concrete walls with supplemental friction dampers. In recent years, a significant amount of research has been conducted on unbonded post-tensioned precast walls because of their construction simplicity and desirable seismic characteristics, such as a self-centering capability, and an ability to undergo large nonlinear lateral displacements with little damage. The greatest disadvantage of these walls in seismic regions is an increase in the lateral displacements as a result of small inelastic energy dissipation. This paper shows that these displacements can be significantly reduced by using supplemental friction dampers along vertical joints between two walls. A simplified performance-based seismic design approach is introduced to reduce the maximum displacement of the walls below an allowable target displacement. Nonlinear dynamic time-history analyses of six-, eight-, and 10-story prototype walls show that the design approach is effective in reducing the lateral displacements to prevent significant damage in the walls under maximum credible ground motions.