Reversed In-Plane Cyclic Behavior of Posttensioned Clay Brick Masonry Walls

Abstract

A series of five large scale clay brick masonry structural walls are subjected to in-plane simulated seismic forces. The walls utilize posttensioning steel to provide flexural strength. The primary objective of the research is to investigate five basic configurations of posttensioning to determine which has the most desirable characteristics for seismic performance. In the study, the variables of interest were (1) bonded versus unbonded posttensioning steel, (2) confined versus unconfined masonry, (3) grouted versus ungrouted masonry, and (4) application of supplemental mild steel for energy dissipation. Following the results of the tests, it was shown that the best performing configuration utilized unbonded posttensioning and confinement. By utilizing unbonded posttensioning, walls have little residual deformation after loading, thus yielding structures that would require very little repair, even after large seismic events. Such behavior comes with the price of reduced energy dissipation, however. Presented in the paper are the results of the tests as well as results of a simple analysis method for prediction of wall capacity.