Mechanism Of Seismic Damage And Collapse Of RC Frame Structure With External Corridor

Due to its simplicity of construction, clear force-transferring path and goodflexibility in architectural planning,reinforced concrete frame structure is a majorstructural type in our society. However there were a great number this kind ofstructures collapsed and killed numerous people in meizoseismal area during theMay12,2008Wenchuan earthquake. It is a great challenge for structuralengineers to improve the seismic performance, especially collapse resistantcapability of RC frame structures. The author focuses on earthquake damage andcollapse of RC frame structure, conducts comprehensive shaking table tests onRC structural models. The effects of infill walls and anchor pattern of beamreinforcement at joint area are tested; damage and collapse mechanism of RCframe with external corridor is summarized; critical equilibrium equation whichdescribes collapse status of RC frame is derived. Contents and conclusions can besummarized as:1. Effects of infilled walls on earthquake response of RC frame structurewere experimentally investigated. The relationship between fundamentalfrequency and PGA was summarized. The damage extent of infilled wall wasscaled into four levels according to the value of the fundamental frequency andthe corresponding story drift of each level was determined.2. Scaled models with standard joints and insufficient anchor joints weretested respectively by shaking table. Effects on failure mechanism of differentanchor methods were discussed.3. The collapse status of Xuankou Middle Scholl building which is a typicalRC frame structure with external corridor was investigated in detail, itsdifferences with adjacent other buildings were analyzed. Preliminary analysis onthe collapse reason was presented.4. In order to verify the above analysis, scaled model of the Xuankou MiddleSchool building was tested by shaking table. Experiment and analysis showedthat the over high dynamic ratio of axial force to strength at columns other thancorridor badly decreased the ductility of these columns, and collapse initializedthis side.5. Based on analysis of the load-carrying capacity of the intermediatecolumns, equation which describe the critical stability of the RC frame structurewere established, corresponding story drift limits were derived.