State‐of‐the‐Art Report on Seismic Performance of Unreinforced Masonry Buildings

A large proportion of North America's older building inventory is of unreinforced masonry (URM), constructed in the absence of mandatory earthquake design requirements, and unquestionably recognized as the type of construction most vulnerable to earthquakes. Awareness of this seismic hazard is relatively new in eastern North America. In addition, the nature of the seismic risk and other engineering constraints there shed a new and different perspective on the problem. This state‐of‐the‐art paper on the seismic performance of URM buildings summarizes knowledge that has already gained some acceptance in parts of North America, and outlines current limitations. Concerns regarding the seismic performance of existing URM buildings are formulated in an eastern North American seismicity context. The various failure modes of URM buildings or components subjected to earthquake excitation are described, and, when possible, illustrated. The state‐of‐practice as required by North American building design codes and standards is summarized. A special analytical procedure of the Uniform Code for Building Conservation, largely inspired from the Agbabian, Barnes, and Kariotis (ABK) methodology for the mitigation of seismic hazards in existing buildings, is reviewed.