Research On Progressive Collapse Of Composite Frame With SRC Column-s Beam

The structural progressive collapse is defined as when a primary structural component fails, and the local failure develops, in a chain reaction mechanism, into a failure that is disproportionate to the initiating damage, for example, the collapse of the whole building.Due to the frequent occurrence of the collapse and heavy losses of lives and property, it is of great significance to study the progressive collapse.Numerous complex structure such as high rise buildings exploit the composite frame with steel reinforced concrete(SRC) column-steel(S) beam, and corresponding work have carried out in past years. However, previous research mainly focus on characteristics of performance of the structure, ignoring the study of progressive collapse resistance of SRC frame structure. In this paper, a progressive collapse analysis of SRC column-S beam composite frame structure is carried out based on the alternate path method, the main achievements can be summarized as follows:(1) To model and analysis the test framework of SRC, and verify the correctness of the method to calculate the plastic hinge parameter, in order to provide the basis for calculating the plastic hinge parameter of composite frame component.(2) A FEA model of spatial composite frame with SRC column-S beam was built in SAP2000. Under the condition of the longitudinal middle SRC column removal, four methods which include linear static, linear dynamic, non-linear static, non-linear dynamic were taken to analysis the frame, the remaining components internal force,the development of plastic hinges and the joint displacement variation tendencies above the removing column were investigated. The analysis that the load was transferred to the adjacent columns and followed nearby principle after removing the columns of the spatial composite frame with SRC column-S beam, nonlinear dynamic analysis is an accurate way to simulate the progressive collapse.(3) Removing the longitudinal middle column, transverse middle column, corner column,and internal column at the first story, non-linear dynamic analysis was carried out for the sudden loss of columns under different column removal conditions. the remaining components internal force, the development of plastic hinges and the joint displacement variation tendencies above the removing column were investigated, and compare the analysis result of four conditions. The analysis shows that the most dangerous condition is the corner column removal.(4) Composite frames witch components suddenly lost in different floor were built, to investigate the change of the joint displacement variation tendencies above the removing column; to investigate the level of different factor impact on progressive collapse such as the number of floors, the length of component failure time and the span changing. The analysis shows that enlarge span will increase the risk of structural progressive collapse.