STRENGTHENING OF EXISTING BUILDINGS AGAINSTEARTHQUAKE WITH CONSIDERATION OF ECONOMICCONSTRAINTS IN DEVELOPING COUNTRIES

摘要

Developing countries located in earthquake prone areas of the world can anticipate huge life andproperty loss during major earthquakes. The study that was recently conducted for the city of Tehranindicates that the economic loss due to a scenario earthquake with intensity IX (MMI) will amount totens of billion US dollars, not mentioning the loss of many lives and the chaos following the event.Obviously such loss may exceed the GNP of the nation. There are many old buildings of various typesin Iran that have the potential for strengthening to withstand earthquakes with lower Intensity, say VIor VII (MMI). For developing or poor nations it would be unreasonable and economically unfeasibleto demolish old buildings that do not meet the requirements of their respective seismic codes. This is aluxury that developing countries cannot afford. Building strengthening should be gradual process inorder to be acceptable to their owners and the authorities and at the same time feasible to implement.One philosophy that may be adopted for developing countries is to survey, identify and categorize thebuildings based on their inherent lateral load resistance levels. The strengthening can be a gradualprocess and therefore be planned for different levels of earthquake intensity. Therefore, the extent ofdamage during earthquakes of different intensities can be controlled without imposing sudden majoreconomic impact on the nations. The survey of several hundred buildings of different structural typesand usage was carried out for the entire city of Tehran recently. Earthquake resistance level for thosebuildings was determined. Based on the above philosophy and the knowledge gained about theexisting buildings, several levels of appropriate strengthening methods were established. This paperpresents the established strengthening methods and their respective cost savings for different levels ofearthquake intensity, compared with full-fledged strengthening complying with the coderequirements.