System Reliability Analysis Of Brick Infill Walls’ Influence On The Seismic Performance Of Frame Structures

Infilled frame structures have flexible and diverse layout, and its force transfer mechanism was also clear and concise; therefore such structures were used widely in China. Usually the infill walls were only as non-structural components in design without considering the role of its bearing capacity, and the cycle reduction factor was used to consider the impact of infill walls on the frame structures in the seismic design. But in the earthquake occurring in Wenchuan at2008, the infill walls which considered as non-structural components were severely damaged, so it’s necessary to study the infill walls’ affection on the seismic performance of frameworks.The seismic performance of most structures depends on its ability to absorb seismic energy and its elastic-plastic deformation capacity, usually the internal damage of structures lead to reduce its bearing capacity under the earthquake. In view of the reliability, the safety reservoir of structures represents the seismic performance indirectly, while the safety reservoir can be assessed comprehensively through the structural resistance and seismic load effects.Based on the domestic and international study of the infilled frame structures, the reliability theory was introduced to analyze the infill walls’affection on the seismic performance of frameworks. First, the analytical frame models which have different layout of walls were established, and the Pushover curve and displacement curve of the models were gained; in addition, the failure state was distinguished according to the elastic-plastic displacement limits, and the characteristics of the damage and distribution of plastic hinges were summarized too. Then, the main failure mode was gained in the basis of the failure path which summarized according to the distribution and emerge order of the plastic hinges next. Finally, the failure performance functions were built by using the theory proposed in this thesis. Based on the failure performance functions, the system failure probability and reliable indicator under seismic loads were gained by Matlab programs according to the system reliability theory. The comparison results between the reliable indicator and system failure probability of different structures showed that the frameworks arranged rational layout of walls can resist lateral force better under seismic loads, and can give full play to the collaborative role, its also can dissipate the seismic energy better. Reflected on the system failure probability, the conclusion is that the framework with walls has greater safety than pure framework, and it can better meet the system reliability requirements in the expected seismic loads.