Hafez Keypour - Ph.D. Graduated, Kandilli Observatory and Earthquake Research Institute, Bogazici University, ۳۴۶۸۴ Cengelkoy, Istanbul, Turkey
Yasin M. Fahjan - Assistant Professor, Department of Earthquake and Structural Science, Gebze Institute of Technology, ۴۱۴۰۰ Gebze, Kocaeli, Turkey
Ali Bayraktar - General Manager, SGM, Seismic Strengthening Center, Inonu Cad. Sumer Sok. Zitas D۱ Blok No:۱۹/۸, Kozyatagi, Kadikoy ۳۴۷۴۲, Istanbul, Turkey

Analysing and strengthening historical structures are challenging task due to the geometrical complexity and lack of knowledge about the inner core material and due to the fact that the masonry material is not able to carry tensile stresses. A better understanding of both gravity load transfer mechanism and lateral resisting system of such structures is the key issue for a comprehensive structural analysis, interpretation of the analysis results and a proper intervention. Nowadays, with the development of computational methods, analyses of historical structures are mostly performed using Finite Element Analyses. Generating a finite element model of the structure require a good engineering experience to make a reasonable geometrical simplification of the complex geometry and a good assumption of unknown inner-core materials. In this study, the design and construction principles for seismic strengthening of historical masonry structures are described in details. The seismic damage characteristics for different elements (foundations, load-bearing walls, arches, domes) are discussed and appropriate seismic strengthening methods are proposed. The importance of minimal disturbance to the system and the crucial to devise a strengthening method that would preserve all historical and architectural attributes of the structure are emphasized. A detailed strengthening procedure are utilized to analyze and strengthening a historical building in Istanbul.