Plastic Analysis Of Mechanical Characteristics Of Steel Frames Under High Temperature

The steel structure building responds to the requirements of the new era countries for building energy conservation and green building,and has been widely used.However,the steel structure itself is not refractory,which makes its mechanical characteristics in high temperature environment become the focus of attention at home and abroad.Studying the fire prevention and fire resistance of steel structures is of great significance for academic research and practical engineering.At present,most of the researchers are concentrated in the elastic phase of the structure.However,most studies focused on the structure of elastic stage,research on steel structure of the inelastic phase is less,especially inelastic phase research of steel structure under high temperature.This paper conducts the following research work on the above issues:(1)According to the actual situation of steel frame structure under high temperature,the parameters of high temperature steel in domestic and foreign codes are summarized,and the more suitable parameters are selected.(2)Summarize the theoretical calculation formula of steel structure under local fire,and use this calculation formula to analyze the internal force of two-layer plane steel frame structure under local fire.(3)The finite element simulation software is used to establish the flat steel frame structure model.Using the ISO834 standard heating curve to simulate the environment temperature,the temperature variation of the flat steel frame structure under different fire conditions is analyzed.Considering the influence of self-weight and external load,the internal force variation of the flat steel frame is analyzed.Concluded the mechanical characteristics response of the steel frame and flat steel frame structure stress and strain contours of the change over time under high temperature;based on the final data,a method of judging the sequence of plastic hinges according to stress and plastic strain is proposed.(4)The finite element simulation software is used to establish the space steel frame structure model.The mechanical characteristics of space steel frame structure at high temperature are analyzed.The stress and strain of whole structure varying with time are obtained.Combined with the obtained data,the method of plastic strain is used to judge the sequence of plastic hinges.The research results hope to provide some reference for future research on space steel frame fire resistance.