Evaluating site effects at Istanbul seismic downholes: numerical studies

Abstract

Examination of the ground records in earthquake zones contributes to more accurate analysis of ground movements and more appropriate designs during the construction process. Depending on the advancement of scienti c and technological developments, the assessment of the impact of ground movements and their possible e ects are facilitated. Bogazici University Kandilli Observatory and Research Institute collects instant data with accelerometers in three deep seismic downhole arrays in _Istanbul, depending on the projects conducted. It is possible to evaluate local ground movements in accordance with the analysis of data in these seismic arrays. One of the fast and e ective solutions in evaluating ground movements is one dimensional seismic analysis. These analyses provide the information on the character and the behavior of the seismic movements between the engineering rock and the surface. Seismic records taken from the engineering rock are also used to determine the seismic behavior on the surface via one-dimensional seismic analysis. The increase in the density of urbanization in the cities due to the several reasons such as the construction of high-rise buildings with deep and shallow foundations, the construction of non-stop highways, etc. in uences earthquake records. In areas where the urbanization is dense, the refraction and re ection behavior of earthquake waves may have an e ect on surface movement records. The downhole arrays in which the accelerometers are installed in Istanbul are exposed to the environmental e ects of the constructions. In this thesis, a series of analyses are presented to show that the surface records which are taken from seismic arrays are di erent from the calculated seismic surface records which are analyzed with one dimensional seismic analysis program.