PERFORMANCE OF CONCRETE BUILDINGS IN MUZAFFARABAD EARTHQUAKE

A major earthquake of magnitude Mw = 7.6 struck the NWFP province of Pakistan and Azad Jammu Kashmir on October 8, 2005. More than four hundred thousand buildings of all types were reported to be partially or fully damaged by ground shaking produced by this earthquake. Reinforced concrete framed buildings with brick or block masonry infill walls have been utilized in commercial and public sector buildings over the last few years. Most of the concrete structures were semi-engineered as they were designed for gravity loads only. Several post-earthquake field visits to Muzaffarabad city were made by the authors to document the performance of concrete structures. In this paper, damages to reinforced concrete buildings are identified and the possible causes are elaborated. The poor performance of reinforced concrete buildings is attributed both to design and construction deficiencies. The observed design deficiencies include poor detailing practice, lack of column confinement, strong beam and weak column and soft stories. The buildings were further weakened by improper compaction of concrete, improper location and treatment of construction joint and notching of column to support lintel beam.