Behavior of Slender, Posttensioned Masonry Walls under Transverse Loading

A conceptual model of the response of slender, posttensioned masonry walls to uniformly distributed, transverse loading is introduced and verified through an experimental program. To validate the model, 12 simply supported 3.54 m (11.6 ft) tall walls with $810\times 100\mathrm{mm}$ $(32\times 4\mathrm{in.})$ cross sections were tested under monotonically increasing transverse (i.e., out-of-plane lateral) loads. Six walls were built using cored clay brick, and the remaining six using hollow concrete block. The walls were posttensioned using threaded steel bars with six walls featuring “unrestrained” tendons (i.e., neither grout nor mechanical devices were used to restrain the bars), while the other six had “restrained” bars (i.e., mechanical devices were used to restrain the bars relative to the masonry), and three magnitudes of effective prestress were investigated. Initial response to transverse loads was linear, but cracking was observed over a broad range of loading. The response of the wall specimens is traced through crack propagation, hinge formation, and development of a plastic section.