This paper presents an investigation of the seismic design of precast concrete wall panels connected along vertical joints with ductile connectors and to the foundation along horizontal joints using unbonded post-tensioning steel. Closed-form expressions are derived to estimate key values defining a trilinear idealized lateral load behavior of the walls. A proposed seismic design approach is developed using base shear demands recommended by current building codes. Unbonded post-tensioned precast concrete walls with substantial initial lateral stiffness can be designed to resist seismic forces �? without yielding of the post-tensioning steel �? by absorbing and dissipating energy in the vertical joint connections. In a companion paper (“Lateral Load Behavior of Unbonded Post-Tensioned Precast Concrete Walls with Vertical Joints�? scheduled for publication in the next issue of the PCI JOURNAL),1 the authors describe a fiber-based analytical model used in a design parameter study of several unbonded posttensioned precast concrete walls with vertical joints. The companion paper presents the results of the analytical parameter study and uses those results to verify the accuracy of the closed-form expressions derived in this paper.
