Progressive Collapse Analysis Of Assembly Truss Beam Composite Floor Based On Connection Failure

The assembly truss beam composite floor is a novel floor system,which is connected by high-strength bolts.At present,the research theories,methods,and design methods for the progressive collapse of typical frame structures have become increasingly mature at home and abroad.The alternate load path method(AP method),by removing the key components in the structure one by one,and examining whether the remaining structure has a new load transfer path,is currently the most widely used method,which can accurately simulate the progressive collapse process of the structure.For the assembly truss beam composite floor system studied in this thesis,whether the existing analysis method can be applied in the case of connection failure remains to be further verified and studied.The main content of this thesis include:Firstly,the composition of assembly truss beam composite floor system and the application and research status of assembly composite floor system are introduced.Then,the current status of the research on the resistance to progressive collapse is introduced,including theoretical research,collapse test research and design method research.Secondly,the main method and content of the progressive collapse design are introduced,especially the first step in AP method,that is,the identification of key component.The thesis find out an identification method with engineering practicability.This method is used to identify the key connections of new type floor using Midas/Gen software.The results show that sensitivity analysis based on the structural response can quickly find out the key connections.Thirdly,the simulation method and steps of failure component removal in progressive collapse dynamic calculation of typical frame structure based on AP method are introduced.The application of the instantaneous loading method,the equivalent load transient unloading method and full dynamic equivalent load transient unloading method in new type floor are discussed.The characteristics and the reasonable value of the relevant time parameters of the three simulation methods are discussed.Comparing the results of the three methods show that the equivalent load transient unloading method and full dynamic equivalent load transient unloading method can accurately simulate the failure process of key connection.Finally,the definition and determination method of the load dynamic increase factor introduced by considering the dynamic effect of the AP method for static calculation are introduced.The provisions of the domestic and foreign regulations for the dynamic increase factor are summarized.The applicability study of the regulations for the value of the dynamic increase factor in the Chinese specification are carried out,and the influencing factors of applicability conclusion are discussed.The study find that the dynamic increase factor of 2.0 is conservative for the linear static analysis,and 1.35 is reasonable for the nonlinear static analysis.