The Practical Way Of An Analysis Of Stability Capacity Of Steel Beam-columns

With the development of economy,steel is widely used in the filed of civil engineering because of its merits.The stability of steel beam-columns is an important problem when it is put into practice.In the steel structure the beam-column is not only under axial force but also bending moment,so its stability will use the theory of ultimate stability.The theory of finite element will be applied to the calculation of bearing capacity.During the process of calculation,geometric and material nonlinearity and initial imperfection will be taken into consideration.This thesis is to study the in-plane stability of such beam-column which is under bending moment.At the same time,it discusses the theory of stability and the method of calculation.The main tasks include:(1)The analysis of deformation and inner force about steel structure beam-column is done and the results indicate that the deflection and bending moment are enlarged because of axial force.So when the large deformation is considered,the second-order effect should be taken into consideration.(2)The steel beam-columns have different cross-section shapes,residual stress and geometric initial imperfection,so the calculation of bearing capacity is very complicated.During the process,geometric and material nonlinearity and initial imperfection will be taken into consideration.This thesis applies the ANSYS program to get the value of stability ultimate.When the program is working,the nonlinear finite element theory is utilized.Through the comparison of the result,it indicates the result of AYSYS is accurate and reliable.Residual stress and geometric initial imperfection can reduce the member's stiffness,so they can reduce the actual bearing capacity of the member.This article induces the general method of analysis about buckling and it discusses the particular process on the calculation of stability bearing capacity. (3)This thesis discusses the formula about the bearing capacity of steel beam-column under axial force and bending moment in the steel design code,the principle of stability factor and the conception of equivalent bending moment.On the basis of stability factor,it discusses the influence of bending moment upon stability factor.AYASYS program was used to calculate the results about the member,whose cross-section is definite and slenderness ratio is different.After comparing the coder results and numerical results,this thesis can prove that the code results are conservative and not exact.Based on a lot of data,this thesis gives the practical method to calculate the bearing capacity of steel beam-column and fits a simple formula to calculate the bearing capacity of steel beam-column.