Research On Failure Mechanism And Collapse Performance Of Steel Staggered Truss System In Fire

Steel staggered truss system (SSTS) is a new structural type which is proved to be economical and practical. The structure has been applied in many practical cases aboard, and the Chinese government is also popularizing the application of this system actively. It should be noted that the security of the steel structure in fire has been paid much attention in recent years. However, as a new structural type, the investigation on the fire performance of SSTS is still at the initial stage. The failure mechanism and mode of the SSTS in fire is studied in this thesis, which is supported by National Natural Science Foundation of China (No.50706059) and the graduate education innovation project of Central South University (No.2010ssxt215). The preliminary investigation on progressive collapse of the SSTS in fire is also conducted.The following works have been fulfilled within this thesis:(1) The experimental research on the small scaled SSTS model has been carried out under fire conditions. The mechanical performance of the structure in fire is obtained, and the comparative research has been conducted on the failure mechanism and mode of the SSTS in fire constructed with different joint types. In addition, the buckling manifestation of the vertical web members of the SSTS is analyzed.(2) Based on the experimental results, the probable progressive collapse of the SSTS in fire is studied by numerical simulation. The3D structural model is established by ANSYS software, and the effect of failure of key members on the fire performance of the SSTS is studied through Alternative Path Method. In addition, some considerable measures are put forward to prevent the progressive collapse of the SSTS in fire.(3) According to the probable progressive collapse of the SSTS in fire, an optimization scheme is proposed aiming at increasing the safety of the structure under fire conditions, and the economic effects of the optimization scheme is also discussed.It is expected that the research achievement in this thesis could play an active role in improving the fire resistance theory of the SSTS. Furthernore, the information in this thesis could provide some scientific basis for establishing the fire resistance design for the SSTS in the future.