Experimental Research On Mouth-Section Steel Columns Of Fire Resistant Properties And Nonlinear Finite Element Analysis

Structure fire resistance analysis is related to the building structure, fire safety and other most difficult problems. High temperature has a significant influence on the structures. The fire can easily cause structural damage even collapse. With the development of infrastructure construction, anti-fire issues of structures highlighted its importance.Steel is more widely used due to its lightweight, high strength, good toughness, plastic, construction progress and high degree of mechanization. But the fire resistance of steel structures is the biggest obstacle in its development. So, fire research on mechanical properties and deformation of steel structure with external cladding is particularly important.Steel columns fire research was carried out by testing its temperature changesand variation of axial deformation. The results of experiments are as followed:1. The reasonable protective layer can effectively slow down the rate of steel columns heating and extend resistance time.2. When the surface temperature of the steel column rose to about 500℃, the deterioration of the mechanical properties of steel columns, the direction of axis deformed, lateral displacement increased rapidly. Finally, the fire resistance of steel basically reached the unstable failure.3. The results analysis shows that axial deformation clearly divided into the expansion phase and contraction phase for steel columns without limit the axial deformation. Contraction phase is very short, and the steel columns quickly damage will be occurred during the contraction phase,4. In case of fire, the component which has two symmetrical axes and has same stability factor can occur instability failure under the axial compressive load.5. The maximum stress and maximum lateral deflection occurrs near the hinge node becasue constraints on the ability of the moment of hinge node is weaker than rigid.In this paper, the finite element method is used to model. The FEM software-Ansys was used to analyze three steel columns with nonlinear thermal-structural coupling methods. The temperature field of steel columns was obtained with the standard temperature increase curve. By comparison with the experimental data, the time- deformation curve and the time – temperature curve are basically consistent with the experimental results. This suggests that Ansys can effectively simulate the behavior of steel columns which are in case of fire.