Lateral load behavior of unbonded post-tensioned precast concrete walls

Abstract

This chapter investigates the experimentally and analytically observed lateral load behavior of unbonded post-tensioned precast concrete walls. Each wall is comprised of six one-storey precast panels that are connected along horizontal joints using unbonded post-tensioned steel, which is anchored at the roof and within the foundation. The bottom panel has regions that are confined and this confinement enables the base panel to sustain the large compressive strains that develop as a result of gap opening displacements that develop along the base of the wall due to lateral loads. The limit states characterizing the lateral load behavior occur as anticipated in the design of the walls and at force and drift levels predicted by the analytical model, except that the experimentally observed drift capacity significantly exceeds the drift capacity predicted by the analytical model. The results demonstrate that unbonded post-tensioned precast walls can be designed to undergo significant nonlinear lateral drift without significant damage, and to retain their ability to self-center, thereby eliminating residual lateral drift. The cyclic lateral load behavior of the walls is nearly nonlinear elastic, with only a small amount of energy dissipation per cycle of loading. As a result, larger lateral drifts can be expected under earthquake loading. However dynamic analysis results show that these walls can be designed to avoid sustaining excessive drift under moderate-to-severe earthquakes.