Performance of Building Roofs in the 2003 Bam, Iran, Earthquake

Roofs covering buildings in the city of Bam, Iran prior to the earthquake of 26 December 2003 can be categorized into three main groups: traditional masonry dome or vault, steel I-beam jack-arch system, and concrete beam-hollow block system. The collapse of nonengineered masonry roofs and floor slabs during the earthquake was the single largest contributor to the large number of fatalities. This paper discusses the seismic performance of each type of roofing and their strengths and weaknesses. The poor seismic performance of traditional domes and vault roofs and unanchored jack-arch slabs are noted and the seismic merits of the anchored jack-arch slabs and concrete beam-hollow block slabs are discussed.