Research On Performance Levels And Deformation Limits Of Infilled RC Frame

The masonry infilled reinforced concrete(RC)frame structure is a widely used structural form in various types of buildings in China.Among them,masonry infilled walls,as non-structural components,often experience the earliest and most severe damage during earthquakes,which affects the functional use of buildings.Therefore,they are crucial components to consider when assessing the performance level of such structures.Currently,research on the damage characteristics and performance levels of RC frame structures is relatively abundant,but there is a lack of sufficient consideration for the influence of masonry infilled walls.In order to further improve the performance level assessment method for masonry infilled RC frame structures,this study first collects and organizes quasi-static test data of masonry infilled RC frame structures to establish a test database.Then,based on the database,limit values for inter-story drift ratio are proposed,and the influence of parameters related to masonry infilled walls is investigated.Finally,the rationality and applicability of the proposed performance level limits are validated through shake table tests on masonry infilled RC frame specimens.The research findings of this study can provide a basis for the seismic damage control of masonry infilled RC frame structures and technical support for the improvement of seismic design methods and the accuracy of seismic safety assessment for such structures.The main research contents of this study are as follows:(1)Collected and organized quasi-static test data of masonry infilled RC frame structures in China,including specific design parameters such as dimensions of walls,beams,columns and material properties of test-piece and constructional measures of infilled walls.Five performance levels for masonry infilled RC frame structures defined by Referring to Chinese regulations.The inter-story drift ratio at which each specimen first reaches each performance level are extracted based on test observations,establishing a localized database of masonry infilled RC frame tests.This provides a data foundation for vulnerability analysis and limit state analysis of masonry infilled RC frame structures with different design parameters.(2)Based on the overall data,inter-story drift ratio limits with an 84%confidence level for different performance levels of masonry infilled RC frame structures in China are provided,along with corresponding fragility curves.The influence of design parameters related to masonry infilled walls,such as aspect ratio,wall openings,block types,and connection methods,on the inter-story drift ratio limits and fragility curves of masonry infilled RC frame structures is analyzed by categorizing the data set according to these parameters.Significance tests are conducted to determine whether there are statistically significant differences between different sample groups classified according to a specific design parameter,providing reference for the selection of fragility curves and performance level limits.(3)A 1/3 scaled model of a masonry infilled RC frame structure is designed and fabricated,and shake table tests are performed to record the damage characteristics,failure states,and inter-story relative displacement responses of different floors and components under progressively increasing peak ground acceleration(PGA)seismic inputs.The corresponding relationship between different performance levels and interstory drift ratio is established to validate the accuracy and applicability of the proposed performance level limits for masonry infilled RC frame structures based on test data.