Abstract- Keypour PhD
NONLINEAR DYNAMIC ANAYLSIS OF HISTORICAL STRUCTURES AND APPLICATION TO AYASOFYA
(Thesis Supervisor: Mustafa Erdik)
This study encompasses the nonlinear behavior of Ayasofya against earthquakes. The historical structures such as mosques, churches and other worship places in seismic regions mostly suffer from earthquake excitation or long-term deformations such as creep. Although Ayasofya is still standing it should not be conceived that it is safe and will not collapse in the future or at the present time. In all cases an effective nonlinear analysis is required to find out the actual behavior of structure, although a linear static and dynamic analysis can give some idea about the overall behavior of structure. For an extensive nonlinear analysis comprehensive material parameters are needed as well as an accurate finite element model. For the latter several models has been tested, taking into consideration of static and dynamic analysis of the model refined the mesh. These refinements have been applied in zones, which had stress concentration. On the other hand the number of elements had been kept constant or as minimum as possible to reduce computing time. There are numerous reports and investigation related to Ayasofya, which were useful for the present study. Most of them are the based on linear elastic analysis. For consideration of structural behavior we need detailed and comprehensive analysis types such as linear and nonlinear static, dynamic, time history, long-term deformation, and also composite analysis. Although most of the analyses were carried out only some of them were successful and got reasonable and significant results (according to present conditions). Because there does not exist a general code for the analysis of monumental structures which is completely different than the general building codes. So we have to decide according to the general analysis and the experiments from other researchers. Several kinds of constitutive models have been tested which are available in the literature. The most appropriate one have finally decided to be the most appropriate for the model. New constitutive models developed by the author were not given successful and significant results because of lack of data and laboratory test.