Impact of retrofitting work on vulnerability reduction of local buildings in Kabul, Afghanistan

Rapid urbanisation of Afghan cities without proper construction regulation has exposed their population to a high risk of damage from disasters such as earthquakes. With the growing construction of local non-engineered buildings and an existing level of hazard of 0.8 g, a high risk of casualties and building damage threatens Kabul in the event of a disaster. This study reports and evaluates a recent retrofitting project in Kabul City by 'Project for City Resilience', carried out under the supervision of the United Nation Human Settlements Program (UN-Habitat) for 48 retrofitted sun-dried clay brick masonry buildings in Kabul. The project was executed by local masons and welders who were trained as a part of the project, and the main tasks included installation of an additional steel frame, additional reinforced concrete foundation ring, ceiling replacement and wall strengthening (via mesh and plaster). After a visual assessment of retrofitted buildings considering the original retrofitting design and actual work done, a vulnerability index for retrofitted buildings was developed based on a behaviour modifier factor, which was assigned to each retrofitting activity using a combination of values and a proportion of scores for each retrofitting activity. The results indicate that training of local masons and welders to undertake retrofitting activities could decrease the damage ratio by 15% - 20% for peak ground acceleration values of 0.3 g and higher. The methods mentioned in this study can be used to make existing sun-dried clay brick masonry buildings sufficiently resistant to earthquakes of moderate-to-severe intensity.