Study On Fire Resistance Of Y-Type Eccentrically Braced Steel Frames In Post-Earthquake Fire

Earthquakes usually cause fires,and secondary fires after the earthquake cause great damage to buildings,causing huge economic losses and casualties.As a new and efficient seismic structure system,the eccentrically braced frame system has been widely used in the field of steel structure and seismic structure.At present,domestic and foreign scholars have done a lot of research work on the seismic performance and fire resistance of eccentrically braced steel frames.However,the research on the fire resistance of eccentrically braced steel frames under the action of post-earthquake fire is in its infancy,and the corresponding work needs to be improved.In view of this,this paper takes Y-type eccentrically braced steel frame as the research object,and carries out the following aspects:(1)Summarizing the material performance parameters of steel structures at high temperature at home and abroad.Combined with the actual situation of the structure,the parameters required in the finite element analysis process are determined.(2)Using ABAQUS finite element software,the finite element model of one-story one-bay Y-type eccentrically braced steel frame was established by shell element,and the effectiveness and reliability of the model were verified by existing experiments.On this basis,the one-story one-bay Y-type eccentrically braced steel frame was analyzed for fire resistance under fire and compared with the fire resistance of the structure under fire.(3)By introducing the damage variable and taking the reduction of ultimate bearing capacity as an indicator,the effects of earthquake damage was researched.On this basis,considering the influence of the height-to-thickness ratio ? of link Web,the length e of link beam,the frame height H and the frame span L,the parameters of catastrophic process,ultimate bearing capacity and fire endurance temperature of the one-story one-bay Y-type eccentrically braced frame in the post-earthquake fire were analyzed,obtaining the variation of ultimate bearing capacity and fire endurance temperature of one-story one-bay Y-type eccentrically braced steel frame under different parameters in post-earthquake fire.(4)The finite element model of three-story one-bay Y-type eccentrically braced steel frame was established by beam element.The correctness of the model is verified by comparison between Pushover analysis and experimental results.On this basis,the finite element model of multi-story Y-type eccentrically braced steel frame was established.The difference of fire resistance between the earthquake with fire and the fire was analyzed.The influence of the fire endurance temperature and deformation of the overall structure of the steel frame was researched with different parameters,obtaining the variation of the fire endurance temperature of the multi-story Y-type eccentrically braced steel frame.In this paper,the combination of numerical analysis and theoretical analysis were used to study the fire resistance performance of Y-type eccentrically braced steel frame under post-earthquake fire.the variation of the one-story one-bay and multi-story Ytype eccentrically braced steel frames in the failure mode under the action and the influence of different parameters on its fire resistance are obtained after the earthquake.Finally,the range of parameters was discussed,and the relatively reasonable value suggestions were given,providing the corresponding theoretical basis and technical support for the design verification of such structures,which has important practical significance and application value.