Characterization of shaking intensity distribution and seismic assessment of RC buildings for the Kashmir (Pakistan) earthquake of October 2005

On October 8, 2005, an earthquake of magnitude M_w 7.6 shook northern Pakistan particularly the Kashmir region. With nearly 73,000 dead, 70,000 injured, 270,000 buildings destroyed, and 180,000 damaged, the earthquake ranks amongst the worst natural disasters in the history of Pakistan and the Indian subcontinent. In this paper, the shaking intensity distribution of the affected region is reconstructed using the limited ground motion data available. Selection of a suite of records representative of characteristics of the Kashmir earthquake at locations of major damage is undertaken. An ensemble of buildings is collated which represents (i) actual Pakistan reinforced concrete design, (ii) general non-seismic and (iii) code-conforming buildings with different levels of detailing. The buildings are subjected to the selected records, including the vertical component of the earthquake ground motion thought to be significant in this earthquake. Conclusions are drawn with regard to the relative performance of the different types of building investigated, the effect of different levels of design and detailing, and the effect of the vertical earthquake component on damage. It is observed that buildings that are seismically designed to contemporary codes would have survived the earthquake. However, the vertical motion would have caused significant reduction of shear capacity in vertical members. The extensive results reported in the paper are useful for practicing engineers operating in areas of high seismicity where limited seismic design and construction quality control exist, as well as code drafting panels interested in the effect of multi-axial excitation on reinforced concrete buildings.