Study On Local Buckling Of The Special-shaped Steel Columns Under Fire Conditions

For special-shaped steel column, it has high bearing capacity, small section, goodseismic performance, building beautiful advantage, but compared with steel reinforcedconcrete special-shaped column, it loses the protection of concrete, and the steel underthe action of the fire, the basic mechanical properties such as its strength, modulus ofelasticity index fell sharply, combined with the special-shaped column is openingthin-walled steel bar that section is irregular, compared with the traditional rolling steelcolumn, the fire area of it is large, the fire resistance of steel special-shaped columnshould be worthy of attention.Special-shaped steel column is the main bearing component, the stabilityperformance of the special-shaped steel column directly determines the security ofconstruction, the buckling modes of special-shaped steel column are overall bucklingand local buckling, if you want to play the best mechanical properties of special-shapedsteel column, you must make sure that special-shaped steel column does not occur localbuckling before overall buckling, therefore, controlling the factors that influence thelocal stability of steel special-shaped columns, is very important to the safety of thebuilding.In view of the above factors, this article is going to study the local stability underfire through nine pillar of H section steel with the fire test, numerical simulationanalysis.Under room temperature, physical properties and mechanical properties of steel isrelatively stable, before undergoing processing components set aside three differentthickness steel plate specimen "dog bone", through tensile test of steel get the mainmechanical performance indexes such as yield strength fy, modulus of elasticity E, inorder to get the main mechanical performance indexes that under high temperature forthe theoretical calculation.Welding residual stress on the influence of H section steel column should not beneglected, and its distribution law is related to the panel size, therefore you must testthis batch components of welding residual stress distribution, in order to make theresults of numerical simulation analysis and experimental results more comparative. In the process of processing components, using3pillar of H section steel of the sameprocess for welding residual stress test.To hold a fire test on nine pillar of H section steel, a certain initial load must beapplied on the component before the test, and remain unchanged throughout the process.Observe and record the test phenomenon, test of plate deformation, the axialdeformation of structures and horizontal fire furnace and the plate itself’s temperaturevariation throughout the process of fire test. Z1~Z3web temperature rise fast anddeformation velocity, were greater than the flange web, webs prior to flange platebuckling; Z4~Z6flange plate temperature rise fast and deformation velocity weregreater than web, flange plate before the web buckling; Z7~Z9flange plate and webplate did not occur simultaneously buckling and the order of the buckling panel isuncertain.Using ANSYS and having finite element simulation to the nine pillar of H sectionsteel that have the same size with the test, compare the data with the test data, we canget H section steel column of local stability performance under the fire. we can get Hsection steel column’ effect coefficient between the flange plate and web plate, whenbuckling occurs under high temperature, and getting the thin wall plate under uniformload’formula that can calculate elastic buckling stress at high temperatures byanalyzing the data.