Out-of-plane seismic assessment of clay brick masonry cavity walls considering different boundary conditions

Abstract

Extensive research has been performed previously on assessing the out-of-plane (OOP) seismic performance of unreinforced clay brick masonry (URM) walls and the retrofitting of URM load-bearing and infill walls having a solid wall thickness. However, comparatively little research has been performed pertaining to URM walls with cavities (i.e., continuous air gaps separating wythes of brick from one another), despite the prominence of cavity masonry construction in various parts of the world. Hence, research was pursued with an emphasis on efficiently retrofitting URM cavity walls to enable the formation of composite behavior when subjected to simulated seismic OOP loading. The research reported herein was based on an experimental testing approach wherein walls were loaded OOP using inflatable airbags. Ten tests total were performed on nine separate URM cavity wall panels located in two separate buildings. The intended outcomes of the research reported herein included determining the OOP behavior of cavity walls in one-way vertical flexure both when bordered and not bordered by rigid moment-resisting reinforced concrete frames; to quantify the improvement in drift levels of cavity walls prior to loss in strength and prior to collapse using a variety of cavity wall ties at different spacing; to establish an effective solid wall thickness for cavity walls with various retrofit tie conditions for use in existing OOP predictive models; and to estimate how the semi-composite action generated by the retrofitting of cavity walls with stiff cavity ties may be predicted.