Title: Lateral Load Behavior and Seismic Design of Unbonded Post-Tensioned Precast Concrete Walls

Author(s): Yahya Kurama, Richard Sause, Stephen Pessiki, and Le-Wu Lu

Publication: Structural Journal

Volume: 96

Issue: 4

Appears on pages(s): 622-632

Keywords: precast concrete; prestressed concrete; shearwalls

DOI: 10.14359/700

Date: 7/1/1999

Abstract:
Unbonded post-tensioned precast concrete walls are constructed by post-tensioning precast wall panels across horizontal joints using post-tensioning steel which is not bonded to the concrete. This paper describes the behavior of these walls under lateral load and proposes a seismic design approach for them. Unbonded post-tensioned precast walls with strength and initial stiffness similar to monolithic cast-in-place reinforced concrete walls can soften and undergo large nonlinear lateral displacements with little damage. The nonlinear behavior is primarily due to the opening of gaps along the horizontal joints. Opening and subsequent closing of these gaps result in nearly nonlinear-elastic behavior under cyclic lateral load. This behavior was investigated using an analytical wall model that is based on fiber elements. The results of this investigation were used to develop a proposed seismic design approach. In this approach, unbonded post-tensioned precast walls are designed to resist code-specified design level ground motions with little damage and to resist survival level ground motions with damage but without failure.