Dynamic Response Analysis Of Large-Scale Steel Structure Under Seismic And Wind Load

The booming of thermal power industry accelerates the construction of Mega-watt generating units, which leads to the technical acquisition and development of large-scale boiler.As an essential supporting part of power plant boiler, the steel structure plays a vital role in the boiler equipment operation to ensure the normal, safe and reliable running. However, there have not been sufficiently effective analysis and design methods for such a large-scale steel structure in china nowadays. In most cases, many national boiler plants introduce foreign sets of large-scale units directly. That's why the key technical issues such as the structure effect by the boiler equipment, the wind-resistant performance under wind load, and the research about the anti-seismic performance and the spatial overall performance of the boiler framework's suspension system with braking installations under the seismic action, demand prompt solution.With the help of modeling by ANSYS and application of finite element method, 3D static analysis of updraft boiler steel frame, the self-vibration analysis of the whole structure, and dynamic response analysis of the whole structure to seismic and wind load are carried out in this thesis. The objective of the thesis is to provide reference and technical back up for the design of Maga-watt boiler steel structure as well as other Special large-scale Steel structure.(1) The 3D static analysis of the structureAccording to the structural type and size of the actual project, the 3D finite element model of updraft boiler steel frame is initially built. After taking constant load, live load, wind load, etc. into consideration in the combinations conditions, the structure is spatial-statically calculated and analyzed. The result provides reference for relative projects in the future.(2) The modal analysis of the integral steel-frameModal analysis is the basis of dynamic structural analysis. The basic principles of modal analysis in ANSYS are introduced. After establishing the integral finite element modal considering the self-weight of boiler and plate girder in ANSYS, the structural model analysis is carried, the top 30 order models are obtained, and the former eight-order vibration mode are listed in this thesis. The analysis about the free vibration characters of the steel frame structure shows that the lateral stiffness in two direction of the structure is relatively uniform, and the structure is comparatively regular, with small torsional rigidity. Also it suggests that the stiffness of side force resistance and torsion resisting stiffness should be improved during the design process.(3) Dynamic response analysis of the integral steel-frame under seismic actionThe dynamic response analysis of the steel-frame under seismic action is made by mode-superposition response spectrum method and time history analysis method. Through the comparison of these two results, we found that the response given by mode-superposition response spectrum method is smaller than that by time history analysis method. The result provides reference for relative projects in the future.(4) Simulation of Fluctuating wind loadThe thesis introduces the theory of fluctuating wind speed time-history simulation and two methods, which are harmony superposition method and linear filter method. Also, it probes into the process of simulation implementation in the computer.(5) Dynamic response analysis of the integral steel-frame under wind loadBy adopting the linear filter method, procedures simulating the fluctuating wind speed time-history is programmed based on MATLAB platform. The procedures generates wind speed time-history including mean wind and fluctuating wind, which converted into wind load time-history acting on steel frame structure. After inputting data into steel-frame model, analysis is conducted on, and the structural response time-history is obtained. The result provides reference for relative projects in the future.