Analysis Of Temperature Field And Mechanical Properties Of Steel Frame Based On Actual Fire

The steel frame structure has the advantages of light weight,good overall stiffness,strong deformation ability,fast construction and green environmental protection,which is suitable for large span and high-rise building and has broad application prospects in China.The steel structure will lose most of its strength when the temperature reaches 600℃ in fire,so the fire resistance of steel structure building has always been the focus of research.At present,the response laws of the component and the progressive collapse mechanism and anti-continuous collapse performance of the steel frame structure under fire are studied at home and abroad.The component or structure is evenly heated by ISO834 standard heating curve,but the curve does not take into account factors such as fire load,location of fire source,geometry and thermal function of fire room which is quite different from the actual fire.In this paper,through the simulation of the non-uniform temperature field and mechanical properties of steel frame in the actual fire scene.The parameter analysis of the steel frame structure under the actual fire is carried out to make up for the defect of heating up with the standard heating curve,and then improve the anti-continuous collapse performance of the structure under the actual fire scene.The main achievement of this paper can be summarized as follows:1,The reasonable heat source parameters are chosen.According to the structure and size of testing steel frame,the fire model of steel frame is established by the software of FDS for the aim of analyzing the temperature field.Due to verify the accuracy of the results from the simulation,the temperature data of the key points is obtained and compared with the testing results.Under this circumstance,the analysis of the temperature development and distribution of the frame beam and column is done during the process of temperature rising.2,Under different temperature,the constitutive models of different materials are chosen.The finite element model of steel frame is built through the right definition of mesh generation,boundary condition and load.At the same time,the results obtained from the temperature analysis are applied to the mechanical behavior analysis of steel frame under fire.The stress and replacement nephogram of the steel frame are output to judged on whether the frame beam and column are invalid and whether the structure has continuous collapse failure.The deflection and mechanic property of structure under fire are analyzed to make a contrast between the stress distribution of normal temperature and high temperature.3,Based on the above method of finite element simulation,the model of steel frame based on practical engineering is established.The single parameter change analysis of steel frame is carried out from the aspects of fire model,fire location and support arrangement.Several main factors that have the greatest influence on the failure of frame beam and column under fire are found out.The influence of fire damage on the continuous collapse of steel frame,the damage on the structure itself and the effect of structure damage on the fire development are solved in three aspects.The design suggestions of anti-continuous collapse of steel structure frame under actual fire are put forward.