Title: Flexural Behavior of Post-Tensioned Concrete Masonry Walls Subjected to Out-of-Plane Loads

Author(s): Roberto Rodriguez, Ahmad A. Hamid, and Jesus Larralde

Publication: Structural Journal

Volume: 95

Issue: 1

Appears on pages(s): 61-70

Keywords: concrete masonry walls; flexure; hollow masonry; out-of-plane loads; post-tensioning; prestress; unbonded tendons;

DOI: 10.14359/527

Date: 1/1/1998

Abstract:
This paper details an experimental study of the behavior, strength, and ductility of post-tensioned masonry walls subjected to out-of-plane loads. A total of four wall specimens was tested to evaluate the effects of the level of post-tensioning force, the size of post-tensioning bar, the reinforcement ratio r, and the fixity of the post-tensioning bar inside the cell (guided vs. unguided) on wall behavior, strength, and ductility. The specimens were tested horizontally using simply supported conditions and applying two concentrated line loads at the third points. The analysis performed showed good correlation between the calculated precracking stiffness using elastic analysis and the actual precracking stiffness of the wall. In the post-cracking stage, deflections were calculated using the ACI and UBC methods, but due to rapid degradation of the stiffness no good correlation was obtained. It was found that in the case of guided post-tensioned bars a predictable precracking elastic behavior developed first, followed by a ductile nonlinear behavior until failure. In the case of unguided specimens, after first crack, the external load increased slightly followed by a gradual drop accompanied by large deflections until failure. The results showed that post-tensioning of masonry walls is an effective and efficient way to enhance the serviceability, ultimate strength, and ductility of hollow masonry walls.