Analysis Of Mechanical Properties Of Rigid And Semi-rigid Steel Frames Under Local Fire

With the maturity of iron and steel smelting technology in modern society,compared with traditional building structures such as reinforced concrete,steel structure building is widely used in the construction industry due to its strong earthquake resistance,environmental protection and short construction period.However,a large number of facts also prove that its poor fire resistance is one of its outstanding shortcomings.At present,there are many researches on the fire resistance of building steel structures at home and abroad.On the one hand,the research focuses on the fire resistance of individual beam-column steel members in the structural system,or on the fire resistance of beam-column joints of a specific structural form.On the other hand,it is about the overall fire resistance of space steel structures.However,in the existing research and analysis on the overall fire resistance of steel structures,beam-column joints are mostly simplified as ideal rigid joints or hinged joints,which is inconsistent with the actual mechanical model of steel beam-column joints.In order to solve the problems in this field,this paper studies the overall fire resistance of space steel frame structures with semi-rigid beam-column connections.The main research contents are as follows:(1)After consulting a large number of domestic and foreign research documents and relevant codes on fire resistance of steel structures,the thermal parameters of steel structures adopted in this paper are analyzed.At the same time,according to the theory of heat transfer,the heat transfer mode and calculation method in case of fire are obtained,which lays a foundation for theoretical calculation and finite element analysis in this paper.(2)Based on the design method of steel structure and the theory of heat transfer,and according to the existing literature,the temperature changes and stress changes of the main components of the space steel frame are summarized when there is a stable fire source in a certain area under the action of uniform load and dead weight.(3)Two spatial steel frame models are established respectively.One model is built according to the rigid connection between beams and columns,and the other model is built by simulating the semi-rigid connection between beams and columns through spring elements.The temperature and stress changes of the components of two space steel frame models under fire(high temperature)are compared,and the conclusion that the fire resistance capacity of semi-rigid steel frame is lower than that of rigid steel frame isobtained by comparing the analysis results,which provides a certain reference for the future research on the fire resistance of the whole steel frame structure.Figure:39;stable:24;reference:57;...