Estimating Likelihood of Severe Damage Due to Earthquakes in Reinforced Concrete Frame Buildings in Afghanistan

Sekandar Zadran, Purdue University

Abstract

Afghanistan has a history of devastating earthquakes claiming many lives and causing extensive damage. It is important to identify buildings vulnerable to ground shaking in an efficient manner and to upgrade or rebuild them to avoid losses during earthquakes in the future. In June 2017, 51 reinforced concrete (RC) school buildings with solid masonry infill walls and no structural walls were surveyed in Kabul, Afghanistan. Besides photographic documentation and location information, building dimensions including column dimensions and masonry wall dimensions, as well as wall orientation information, and number of stories above ground were recorded. To rank these buildings in vulnerability and to identify which ones, if any, would need to be upgraded to avoid high likelihood of severe damage at different levels of ground shaking, a method based on the Priority Index (Hassan and Sozen, 1997) was used. Ratios of total cross-sectional areas of ground story columns and masonry walls to total floor area above ground formed two of the key parameters. Peak ground acceleration (PGA) was used as the parameter to indicate the level of ground shaking. Column-to-total floor area and masonry wall-to-total floor area ratios were divided by PGA to differentiate between different levels of shaking intensity. The method is calibrated and a threshold relationship is established to distinguish whether a building is more likely to sustain severe damage (“more vulnerable”) or less likely to do so (“less vulnerable”) using data from buildings surveyed following the 2016 Meinong, Taiwan earthquake. In particular, observations and measurements from survey of 50 RC frame buildings with no structural walls but with solid brick infill walls and located near ground motion recording stations were used. Peak ground acceleration recorded by the nearest ground motion recording station (within 5 km of a building) is used to scale the column and infill wall ratio based indices. Various combinations of the indices were studied to find a threshold description. Threshold expression choice was based on 1) the success rate in identifying buildings that sustained severe damage as “more vulnerable” while 2) minimizing the likelihood of identifying buildings that did not sustain severe damage as “more vulnerable.” The primary objective in establishing this threshold is to minimize loss of life while the secondary objective is to be effective and feasible to implement. Threshold expression found for buildings surveyed in Taiwan was then used to identify school buildings in Kabul that are more vulnerable to severe damage at different seismic hazard levels expressed in terms of PGA. The buildings were ranked in vulnerability using the Priority Index (Hassan and Sozen, 1997).

Degree

M.S.C.E.

Advisors

Irfanoglu, Purdue University.

Subject Area

Civil engineering

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