The Effect Of Wall Opening Sizes On Unreinforced Masonry Subjected To Dynamic Loading

Abstract

Low income unreinforced masonry structures in the southwestern region of the Western Cape Province of South Africa present a safety and economic threat if subjected to moderate intensity seismic activity. Previous experience and investigations conducted have shown the vulnerability to damage and/or collapse when these structures are subjected to moderate seismicity. Most unreinforced masonry buildings in South Africa were constructed prior to the first codified provision for seismicity contained in SABS 0160 of 1989. Numerous other residential unreinforced buildings were constructed since then. To date these types of structures have not been evaluated for South African conditions, and concerns have been expressed whether these structures conform to the new codified guidelines contained in SANS 10160-4 of 2011, which is almost a verbatim repetition of the European code for seismic design. Before an analysis of unreinforced masonry buildings can be conducted, it is imperative to determine the effect which opening have on unreinforced masonry walls. This was achieved by conducting experimental tests on four unreinforced masonry walls with various size openings, to determine its effect on the in-plane stiffness, failure frequency and failure displacement. Experimental results show that there is a relationship between the opening sizes versus the wall stiffness, failure frequency and failure displacement.