Investigation of Seismic Vulnerability of Historical Brick Minarets (Case Study: Historical Ziar Minaret) SeyedSalar Ahmadi Ahmadi_sslr@yahoo.com Date of Submission: September 16, 2020 Department of Civil Engineering Isfahan University of Technology, Isfahan 84156-83111, Iran Degree: Msc Language: Farsi Spervisors: Dr. Mohammad Reza Eftekhar (eft@iut.ac.ir), Dr. Payam Asadi (asadi@iut.ac.ir) Due to historical, cultural and social value of ancient masonry structures, they should be more considered. Minarets were used for lightening of the roads at nights and also for saying Azan many years ago and they were one of the main parts of old cities in Iran. In this research, seismic vulnerability of a 900-year-old minaret (Ziar minaret) which was built by masonry materials, has been done. For his purpose, some brick specimens which dates back to centuries ago, was tested. Then, masonry prisms were used to obtain mechanical properties of brick and mortar together. Next, linear and nonlinear seismic behavior of minaret was investigated. In this regard, ambient vibrate experiment was done to reach natural mode shapes of the structure. Abaqus software was chosen for Frequency, static and dynamin analysis. After verifying the frequency of FE model of the minaret with experimented one, non linear analysis of minaret was triggered. To verify nonlinear analysises, the confined masonry wall, tested by researchers in real dimentions, was used and it it was compared with the one that was modeled in Abaqus. The comparison of location of the cracks and the diagram that came out from Push-over analysis, illustrates that nonlinear modeling was correct. Finally, minaret structure was analyzed under 11 records of scaled earthquake with Time History analysis. For parametric investigation of the minaret structure, shortened minarets with height of 40, 30, 20 meters, were modeled and time history analysis was done again on these minarets. Results show that the fracture of minaret structure happens and starts from bottom of minarets. In higher minarets (with ratio of hight to width from 9 to 6) with regards to impression of higher modes, in upper rigions of minaret, fracture would happen, although in shorter minaret yield points are located in the bottom of minaret. Key Words Minaret Structure, Brick Masonry Materials, Abaqus Software , Modal Analysis , Nonlinear Analysis , Seismic Vulnerability