Seismic safety screening method for Istanbul metropolitan city

Most of Turkey's existing building stock was constructed based on older design standards or non-engineered design. This doesn't mean that all of these buildings might be hazardous or suffering severe damage by earthquakes. It is necessary to identify those that are at risk and carry out reconstruction or seismic retrofit. This is a common problem of all earthquake-prone countries, is not unique problem for Turkey. But, reliability or inadequacy in construction procedure is unique to each country and for this reason, the method for seismic evaluation of existing buildings should be determined carefully. Also, selected procedure should be tested and calibrated based on the data compiled from damage surveys in relevant country. In this study proposed procedure is called Seismic Safety Screening Method, SSSM, which is adopted and modified from Japanese Seismic Index Method, JSIM. Both methods give seismic capacity index of buildings, which is checked against demand index, by referring the orientation, size and material properties. If seismic capacity index is less than seismic demand index, it indicates that the building might suffer severe damage or collapse. The method can be applied to medium-rise reinforced concrete buildings. The seismic capacity index gives effective information to quantitative understanding, not a subjective assessment data. This index is then modified by several coefficients that reflect the quality of materials and workmanship, and architectural features of Turkey's buildings. The calibration of several coefficients in this proposed method has been done by considering the studies carried out in the pilot area, Zeytinburnu, after Istanbul Earthquake Master Plan was completed. Nonlinear static or dynamic analyses results of several existing buildings are used to calibrate coefficients. Here, as an example, nonlinear dynamic analyses results of moderately damaged building by 1999 Marmara Earthquake and SSSM results are compared. It can be concluded that SSSM is suitable for Turkey's buildings.