J.R. Bean1, A.E. Schultz2, and C.R. Drake3
1,3Graduate Research Assistant, Dept. of Civil Engineering, University of Minnesota, USA, bean0032@umn.edu
2Associate Professor, Dept. of Civil Engineering, University of Minnesota, 500 Pillsbury Dr. SE, Minneapolis, MN, 55455, USA, schul088@umn.edu
ABSTRACT
An experimental program is described to investigate the behavior of slender, post-tensioned masonry walls to uniformly-distributed, transverse loading (i.e., horizontal loads perpendicular to wall surface, such as wind pressure or earthquake forces). Twelve 3.54 m (11.6-ft) tall walls with 810 x 100 mm nominal (32 x 4 in.) cross-sections were tested under monotonically increasing transverse loads. Six walls were constructed using cored clay brick, and the remaining six using hollow concrete block. The walls were prestressed using threaded post-tensioning bars, and six of the wall specimens featured unrestrained tendons (e.g., the cavities containing the tendons were ungrouted and mechanical devices were not used to restrain the tendons), while the other six had restrained tendons (e.g., mechanical devices were used to restrain the tendon relative to the masonry). Three different magnitudes of effective prestress were investigated.
The walls were tested vertically in a frame that simulated pinned end conditions, with uniformly distributed lateral load being simulated by a servo-controlled hydraulic force actuator acting through a whiffletree with eight load points at four locations along the wall height. Experimental observations of wall behavior are presented. Maximum deformation capacity of the walls is evaluated in light of these experimental observations.
KEYWORDS: prestressed masonry, post-tensioned masonry, tendon restraint, slender walls, out-of-plane bending, flexural
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