Seismic Behavior And Fragility Analysis Of Unreinforced Masonry Structures

Low cost, easiness to construct and availability of material make unreinforced masonry structure (URM) one of the most common structural types in the towns and rural areas of our country. Also, many civilizations are remembered with tremendous masonry structures build in their era. Due to the uncertainties of its material and modeling, and non-linear dynamic behaviore, URM is difficult to be analyzed. While in the past few years, many earthquakes happened and URM showed high vulnerability to seismic loading. Now the researches of URM in China mainly focus on deterministic analysis or considering only the uncertainty of one factor. So it’s important to do fragilty analysis of URM since this method can concider uncertainties of many factor.This thesis first introduces the mechanical character of URM walls and the modeling method, including elastical and plastical behavior of URM walls and equations to calculate elastical and plastical stiffness. Then equal frame method (EFM) is applied by using the theoty obtained in the research of solid URM walls. After setting shear hinges which can present the non-linear bebavior of URM walls, EFM can modeling the non-linear behavior of performed URM walls. By using SAP2000with user-friendly interface, the EFM is verified by compared with the experimental results in University of Pavia and ISMES. Then SAP2000is called by VBA, which can make the modeling, analysis and result output automated. This can make it easy to do large number of analysis.After the EFM is verified, deterministic seismic analysis is runned for a one bay two floors URM and one bay one floor URM, including modal analysis, Pushover analysis and non-linear time history analysis. Then, seismic fragility curves of the one bay two floor building are derived by using clound method, dynamic Pushover curves method and stastical analysi by using Latin Hypercube sampling. After comparing the seismic fragility curves obtained by different method, we come to the conclusion that the seismic fragility of URM is the highest by using statistical method, lower by clound method and lowest by clound method.