The cold - formed square hollow section columns are widely used in various structures such as building structure , trusses , space frames and offshore plates etc . this paper is mainly doing the research on load carrying capacity of the cold - formed square hollow section columns under axial load , the paper includes the following main contents : ( 1 ) an elastic buckling stress for cold - formed square hollow section is presented by finite element analysis , and is compared with the result given by classical elastic buckling theory ; ( 2 ) the elastic - plastic non - linear behavior of the cold - formed square hollow section columns analyzed by ansys is presented ; ( 3 ) by using material model , and geometry nonlinear analysis , the cold - formed effect to stub columns of cold - formed square hollow section is studied ; ( 4 ) by using an material model , the geometry nonlinear analysis , the influence of initial geometrical imperfection to stub columns of cold - formed square hollow section is also analyzed ; ( 5 ) the load carrying capacity of the cold - formed square hollow section columns , which are including the cold - formed effect and influence of initial geometrical imperfection is analyzed by non - linear finite element , and the theoretical analysis results are compared with the results of experimental study and the results calculated by specification gb50018 - 2002 冷弯方管作为轴心压杆广泛用于房屋结构、桁架、网架、塔架以及海洋平台等结构中，本文主要研究轴心受压冷弯方管的承载力性能，内容主要包括以下一些： ( 1 )对冷弯方管的弹性临界应力进行有限元分析，并与经典理论结果进行对比，以验证有限元程序的适应性； ( 2 )阐述冷弯方管采用有限元弹塑性非线性分析理论及应用ansys软件的非线性分析方法； ( 3 )采用弹塑性模型，考虑几何非线性及材料非线性，对不同宽厚比的轴心受压冷弯方管柱的冷弯效应进行有限元非线性分析研究； ( 4 )考虑冷弯效应对屈服应力的影响，对不同宽厚比的轴心受压冷弯方管短柱在不同初始变形下的承载力性能进行有限元非线性研究； ( 5 )考虑冷弯效应、几何初始变形，对不同长细比和不同宽厚比的轴心受压冷弯方管长柱的承载力性能进行有限元非线性研究，并与试验结果以及我国现行规范gb50018 ? 2002计算结果进行对比分析。
In the procedure , the column is first divided into a finite number of small segments in equal length . the deflection - curvature relation of each segment is determined using the finite - difference method . the final nonlinear algebraic equations are then obtained by means of the equilibrium condition for each segment 运用这种方法时，先将长柱离散成若干等长的柱段，利用差分方法求得各柱段截面上的挠度与曲率的关系，再根据各截面上力及力矩的平衡条件，得到一组关于荷载与变形关系的非线性代数方程组，本文采用曲率增量法求解该方程组。
Meanwhile the effects of slenderness ratio and load eccentricity on the ultimate load - capacity of slender composite columns are numerically analyzed and discussed in detail . then a t - shaped slender composite column under axial load and two groups of slender composite columns of rectangular cross section subjected to combined biaxial and lateral loads are analyzed , the load - carrying and deformation behaviors of such columns are analyzed and discussed 在此基础上，对一偏压荷载作用下的t型截面组合长柱和两组横向与偏压荷载共同作用下的矩形截面长柱分别进行了实例计算，就不同荷载情况下组合长柱的受力与变形特性进行了分析和讨论。
The influence of nano - al2o3 on the sintering and the properties of the si3n4 ceramics was researched in this paper . the samples with different amount of nano - al2o3 were obtained by using pressureless sintering at 1600 , 1650 , 1700 in the nitrogen atmosphere . the microstructure and the composition of the ceramics were determined by the means of x - ray , sem , micro - hardness meter etc . it is show that the sisty ceramics can be densified at 1650c to % percent of the theory density through the addition of nano - al2o3 ( the value could be 90 percent by other technique ) . the crystalline growth of the cylindrical - si3n4 and the ratio of its longitude to its diameter are increased with the addition of nano - al2o3 . a uniform microstructure and an fined crystal as well as more sialon phases can be obtained in the si3n4 ceramics through the addition of that 实验结果表明：在碳管炉中、氮气保护下进行烧结，添加剂为纳米al _ 2o _ 3粉末时，由于纳米粉末的高活性、高烧结驱动力，在1650就可使si _ 3n _ 4完全地烧结，并使其致密度可达理论密度的96以上(比其它工艺高6左右) ；同时，纳米al _ 2o _ 3地加入大大促进了长柱状? si _ 3n _ 4的生长和发育及柱状晶长径比的提高，使微观结构均匀、细化，形成了更多力学性能优异的固体? sialon相，减少了不利于陶瓷材料性能的晶间玻璃相，净化了晶界。
As for the limit bearing capacity formula of the concrete filled steel tube long column subjected to axial compress , we lead to the tangent modulus and the conception of metal material . the high strength core concrete is divided into two kinds of situations : single axial loading conditions and triaxial loading conditions 在推导钢管混凝土轴心受压长柱临界承载力公式时，论文利用材料的切线模量，分别推导了钢材和混凝土的切线模量公式。对于混凝土的切线模量，本文分成单向受压和三向受压两种情况考虑，并分别得出切线模量公式。
In the procedure , the column is first divided into a finite number of small segments in equal length . the deflection - curvature relation of each segment is determined using the finite - difference method . the final nonlinear algebraic equations are then obtained by means of the equilibrium condition for each segment 运用这种方法，先将长柱离散成若干等长的柱段，利用差分方法求得各柱段截面上的挠度与曲率的关系，再根据各截面上外力与抵抗力的平衡条件，得到一组关于荷载与变形关系的非线性代数方程组；本文对该方程组采用载荷增量法进行迭代求解。
This paper conducts a study of the influence of core concrete performance upon the stability factor of axially compressed medium long concrete - filled steel tube column on the basis of comparison of the axial compression test results of long column made up of common concrete filled steel tube and medium long column made up of lightweight aggregate concrete - filled steel tube , and in accordance with analysis of the constitutive relation curves between both the common and lightweight aggregate concrete 摘要通过对钢管普通混凝土长柱和钢管轻集料混凝土中长柱的轴压试验结果的比较，结合对普通混凝土和轻集料混凝土的本构关系曲线的分析，研究了核心混凝土性能对钢管混凝土轴压中长柱稳定系数的影响。
Since the pure cylindrical vesicles without ends are unstable even non - existence , approximations of torus and cylinder with spherical ends are utilized . the result from the former approximation means the condition of infinite long cylinder , which gives us no useful information . by spherically topological approximation , we get a set of conditions , all of which specify the range of parameters 利用环拓扑结构近似，我们得到了无限长柱状膜的方程，但此方程没有给出任何有用的信息；利用球拓扑近似，无论直接变分还是间接变分，都给出了一组条件，规定了参数的一个取值范围，所以，球拓扑近似比环拓扑近似更实用一些。
The specimens of rpc filled in steel tube slender columns were studied , and test results showed that the ultimate loading capacity and maximum displacement decreased as the slender ratio l0 / d increased , the relative loading when the lateral deflection increasing fast decreased as the l0 / d increased 对钢管活性粉末混凝土中长柱的实验研究表明，中长柱试件的承载力和极限位移都随着试件的计算长径比l _ 0 d的增大而降低(或减小) ，侧向挠度迅速增大时的相对荷载也随着计算长径比l _ 0 d的增大而降低。
The parameters are measured respectively during the experimental process , such as bearing capacity , deformation , strain and so on . it concludes that when the other conditions is equal , the limit bearing capacity of the concrete filled steel tube long column subjected to axial compress is reduced along with the long diameter ratio increased 从试验结果可以看出：钢管混凝土轴心受压长柱的稳定承载力，在其他条件相同时随长细比的增大而逐渐降低；试件在最大承载力状态下，钢管表面的平均纵向应变已超过钢管的屈服应变值，破坏呈现为非弹性失稳破坏。
