Applied Research On Second-Order Elastic-Plastic Analysis In Steel Structures Anti-Seismic Design

With the social progress and the scientific development, high-volume steel structures have appeared in China. But China is a earthquake prone country. The randomeness of earthquake is difficut to grasp. It is difficult to accurately determime that the collapse of structure when the structure components don't afford the plastic deformation in particular of the steel structures in plastic state. The first order elastic analysis based on the design capacity dosen't consider the structure deformation and the the interaction between external forces and structure, so it is not ture to reflect the situation in the force structure. The second-order plastic analysis of the structures with more bars which is more complex body structures system is significance. In this article, according to National Norm's three standard requirements'"no damage in minor earthquake, it can be repaired in intermediate earthquake, not fall in big earthquake', engineering model was elastic and plastic analyzed and preliminary assessment of the seismic performance was got, and reference data of design optimization for the model were provided.Firstly, in this paper, the development of domestic and foreign steel construction and the advantages of steel structure system were presented. The basic requirements of seismic design, seismic design goals and some analysis method were also introduced. The time-history method's basic principles, procedures,vibration model, restoring force model and the establishment and solution of the vibration equation were discussed in detail. The basic theory of elastic analysis, implementation steps, loading model, target determination were expatiated. The baisc conception, causes and computational method of the second order P-? effect were summerized.Secondly, the steel structure was analysed by mode-superposition response spectrum method, elastic time history ,nolinear time history and elastic-plastic analysis base on consideration of the second order P-? effect and no-consideration of the the second order P-? effect with the PKPM soft.Finally, the results were evaluated. The results show that the structure in the X direction and Y direction meet to the requirements for seismic resistance. In the elastic stage, the difference between consideration of second-order P-? effects and no-consideration of second-order P-? effects analysis is no more than 5%, which has little effect on the structural analysis. In the elastic-plastic analysis, the difference between considerarion and no consideration ofecond-order P-? effects analysis is more than 5% and the impact of the earthquake can not be ignored. In the elastic-plastic history analysis must take P-? effect into account. Anti-collapse checking shows that the layer displacement curve can cross over more opportunities and the rare event earthquake response spectrum. There are seismic surplus so the structures design is too conservative and elements have optimized the space. In the requirement of seismic performance, sectional area of structural components can be reduced,and material can be reduced economically.