STRUCTURAL REHABILITATION OF DAMAGED RC BUILDINGS AFTER THE 1 OCTOBER 1995 DİNAR EARTHQUAKE

This paper contains technical information related to the Dinar project for the rehabilitation of moderately damaged reinforced concrete buildings after the 1 October 1995 Dinar earthquake. The structural appraisal of the damaged buildings, analytical studies leading to decisions regarding structural rehabilitation or demolition, the supervision on site of the rehabilitation and the overall coordination of the project was entrusted to the Middle East Technical University Earthquake Engineering Research Center [METU-EERC] by the Turkish Ministry of Public Works and Settlement. The project involved the rehabilitation of 35 moderately damaged RC buildings with a total floor plan area of 22 000 square metres.     

ENGINEERING EVALUATION OF THE 1 OCTOBER 1995 DİNAR EARTHQUAKE (ML = 5.9)

In 1995, a swarm of earthquakes affected the city of Dinar, Turkey, which is located in Southwest Anatolia and has a population of 35 000. The mainshock having a local magnitude of 5.9 occurred on 1 October 1995. It was preceded by foreshocks in the previous four days, the largest one with a magnitude of 4.7. These foreshocks initiated structural damage in many buildings, which was then severely aggravated by the mainshock and a strong aftershock two hours later, with a magnitude of 5.0. Numerous aftershocks were recorded throughout the following three months. Strong ground motions were recorded within the city. The mainshock produced peak horizontal accelerations of 0.28 g and 0.29 g. The Dinar earthquake caused a death toll of 92 and more than 200 injuries. The economic losses due to structural damage alone are estimated at 250 million USD.     

ECONOMIC ASSESSMENT OF THE SEISMIC RETROFITTING OF LOW-COST APARTMENT BUILDINGS

When structural retrofitting of buildings is required due to seismic safety considerations, building owners or government officials are faced with a crucial decision whether to demolish and rebuild their buildings, or retrofit them. Simple decisions based on fixed proportions, such as demolish and rebuild if retrofit costs exceed 40% of the replacement cost, may be misleading. A financial analysis should be carried out considering all the revenues and costs of the building during its life time. A low-cost residential apartment building that has a construction cost of $140/m² is selected in this study to represent the vulnerable buildings in developing countries under seismic risk. Life-cycle cost analysis approach is employed to value the rebuild or retrofit alternatives to compare economically. Economic assessment has been carried out for various parameters. It has been found that the age of the building and the retrofit ratio are dominant parameters among the others. The critical retrofit ratio (percent of retrofit cost to initial construction cost) varied from 25% for 40 year old buildings to 67% for 10 year old buildings. It is suggested that economical decisons should not be made simply by comparing the retrofit costs to initial construction costs.