Out-of-plane in-situ testing of masonry cavity walls in as-built and improved conditions

Abstract

Extensive research has been performed previously on assessing the out-of-plane (OOP) performance of unreinforced masonry (URM) walls and retrofitting URM load-bearing and infill walls for OOP capacity. However, little research has been performed within New Zealand pertaining to clay brick masonry walls with cavities, despite their prominence in the building population. Hence, further research was pursued with an emphasis on retrofitting URM cavity walls so as to form composite behaviour efficiently. This research was based on an experimental testing approach wherein walls were loaded OOP using inflatable air bags. Testing was performed on ten URM cavity walls in two separate buildings. The intended outcomes of the research reported herein were as follows: Determine the behaviour of cavity walls in vertical flexure when bordered by rigid moment-resisting reinforced concrete (RC) frames; Determine the improvement in drift levels in cavity walls prior to loss in strength and prior to collapse, using a variety of cavity wall ties at different spacings; Determine which cavity ties are most effective in improving OOP cavity wall performance; Determine how the load-based capacities of the test walls correspond to design basis earthquake demands in Auckland (area of moderate seismicity) and in Hastings, New Zealand (area of high seismicity); and Determine what effective solid wall thickness should be assumed for cavity walls with various retrofit ties conditions for use in existing models regarding the OOP flexure of URM walls