Simplify Calculation And Finite Element Analysis Of The Behavior Of H-section Steel Column In Fire

In this paper, simplify calculation and finite element analysis of the behavior of H-section steel column in fire is investigated.(1)Simplified computing formula of the fire resistance for H-section steel column is established. Experimental results and simplified results are compared and analyzed. The result reveals that slenderness ratio of steel column along weak axis is bigger than that along strong axis and critical force on instability of steel column along weak is smaller than that along strong axis in fire.Steel column along weak axis are failed at first. The simplified computing results show in good agreement with the experimental results for axial free expansive column.(2)Finite element analysis of H section steel column in fire include geometrical nonlinear analysis and material nonlinear analysis.Basic equation are developed by Updated Lagrange Formulation and analyzed by incremental approach. At first, the virtual work equation with the form of the matrix is deduced. Linear and nonlinear stiffness matrix of spatial steel column element is also deduced by the stress-displacement relation. The final results show the geometrical nonlinear stiffness equation of spatial steel column element. The second, in terms of plastic machanics theory which include yield conditions (V.Mises),consistency condition,flow rule,stress-strain incremental relation(strain increment can be made up of elastic strain increment,plastic strain increment,temperate strain increment), pastic and elastic- plastic stiffness matrix of spatial steel column element in fire can be deduced. The final results show thermal-elastic- plastic stiffness equation of spatial steel column element. The lateral deflection of spatial H-section steel column in fire can be computed by fortran program .The computing results show in good agreement with the test results.