| The concrete-filled steel tube(CFST)structure has the advantages of high strength,good ductility and simple construction,and has been widely used in engineering practice.The concrete-filled steel tube truss column structure not only has the characteristics of balanced stress and light weight,but also has the high strength of CFST structure,which is an excellent compression structure.But at present,there are few studies on the section parameters of CFST Truss and out-of-plane stability of CFST structures.In order to make the CFST Truss column structure easy to calculate and use in engineering practice,using the “ Plate-Beam Theory ” of Professor Zhang Wenfu and the equivalent principle of web members,the bending and torsional buckling analysis of concrete-filled steel tube truss column under different boundary conditions,different load combinations and different section parameters are carried out.The finite element software ANSYS was used to establish a model to verify the theoretical results.The main research contents are as follows:(1)Based on the "plate-beam theory" and the principle of equivalent web members,the bending and torsional buckling of double symmetric section and mono-symmetrical section of concrete-filled steel tube truss columns under compression and bending are analyzed.Using the principle of deformation decomposition,the total strain energy of flexural-torsional buckling of the concrete-filled steel tube truss column is obtained,and its section parameters: bending rigidity,restrained torsional rigidity and free torsional rigidity are obtained.Through the analysis of the initial stress potential energy of each plate under the action of compression and bending,the total initial stress potential energy of the flexural-torsional buckling of the concrete-filled steel tube truss column is obtained,and the asymmetry coefficient of the mono-symmetrical section is obtained.Calculate the load potential energy of the component under different loads,and add the total strain energy,the initial stress potential energy and the load potential energy to derive the total potential energy equation for the flexural-torsional buckling of the concrete-filled steel tube compression-bending component.(2)Using the principle of energy variation,an approximate solution to the critical load of flexural-torsional buckling of concrete-filled steel tube truss columns under compression and bending.Considering the boundary conditions of the simple support and the cantilever respectively,using different Fourier series as the modal test function,and respectively give the solution of the modal test function as one item and infinite item.For one item series solution,the calculation formula of the critical load is given;for the infinite item series solution,a buckling equation in matrix form is given.When the selected modal test function has enough terms,the approximate solution tends to converge.(3)Establish ANSYS finite element model and perform modal analysis.10 different concrete-filled steel tube truss columns were established by changing the span,load factor,load acting position and section parameters of the members.The critical load value of the flexural-torsional buckling of the member under the combined load is extracted and compared with the theoretical value to verify the accuracy of the theoretical solution.Figure [ 20 ] table [ 24 ] reference [ 75 ]... |
