The Analysis Of Temperature Field And Allover Effect Of Steel Frame Structure In Fire

High-temperature analysis of steel structures has been started relatively early in foreign countries,and carry out the experiment with a more comprehensive analysis of research results.But we research this area slightly behind.Both the material properties, the mechanical properties of steel under high temperature and the structural response under high temperature are less of research and experiments.At present,fire resistance of steel is still depending on component-based design method.The shortcomings of this method had been known in many experiments.It is difficult to simulate the real load distribution and the restrict of members.So the method of based on the overall structure must be fire resistant design of the future direction of development.In addition,in recent years,performance-based design methods have been greatly developed.It is very useful for calculating the temperature distribution in space and other parameters(high of smoke,Concentration of harmful gases,etc.)This article discusses a new method of structure analysis under high temperature.It coupled performance-based design with finite element structural analysis.Just as well, we can either draw the parameters intuitively after the fire or work out the structure response under high temperature.The author used the steel frame structure as a model for the analysis,and based on a practical project to establish a geometric model.And use the performance-based design software of FDS to simulate the whole process of structure in the fire.And work out the temperature changes of different points in fire. The author considers the non-linear properties of steel at high temperature,including thermal conductivity,specific heat and thermal expansion.The values of these parameters are referenced to the foreign practice,and combined with the actual situation in this paper analyzes the value.And then use the f'mite element analysis software to calculate the internal temperature field of the beam.In this article,the author compared the temperature field of the simulation and the ISO836,and gives the difference between the two.At last,the author analysis the stress and deformation of the structure under the local high temperature by the method of overall structure.And the author suggested that coupled performance-based design with finite element structural analysis to analyze the structure,using the temperature field of performance-based analysis,and then calculating the thermal stress and deformation by finite element program.