Buckling Analysis Of Steel H Column Under Non-uniform Temperature Distribution

Recently,H-section steel columns have been widely used in steel structures due to their properties of lightweight and high-strength.As we all know,steel members have a disadvantage,that is,poor fire resistance.The mechanical properties such as elastic modulus and yield strength of steel are greatly reduced at high temperature.Thus,the load-capacity of H-section steel columns under the fire load is a main issue of their mechanical performance research.Non-uniform temperature distribution caused by different types of fire load makes the mechanical properties of the cross-section be asymmetrical and flexural-torsional buckling occurs.In this paper,the critical loads of H-section steel columns subjected to non-uniform temperature distribution are investigated by theoretical and numerical method.The main contents in this paper are as follows:1.The fire-induced thermal gradient along the flanges is obtained by using simplified Fourier heat condition equation.2.Based on that,an analytical study is presented to calculate the critical buckling load,which considers the per-buckling stress and bowing effect due to the non-uniform temperature distribution through the cross-section.The analysis is accomplished using the Rayleigh-Ritz method.The analytical solution is validated by using the finite element analysis method.The correctness of the finite element model is verified by the buckling analysis of the H-section steel columns under four-sided fire.3.A good agreement is demonstrated by the comparison between the theoretical solutions and the finite element solution results for short and mid-length columns.With the increase of the length,the difference between the theoretical solutions and FEA results increases,but it is still acceptable in practical engineering.4.Parametric study is also performed for different sections including different values of length,thickness ratio and width-to-height ratio.The results show that with the increase of length and width-to-height ratio,the faster the critical load decreases,which means that the influence of non-uniform temperature distribution is greater.However,the thickness ratio has little influence on the critical load,which can be ignored.