开口加劲肋板稳定极限承载力分析

以三汊矶湘江大桥自锚式悬索桥主梁钢箱梁人行桥面板为研究背景,以开口加劲肋板为研究对象,研究不同参数对开口加劲肋板弹性屈曲荷载的影响,并考虑几何和材料非线性的影响,分析了不同残余应力、不同初始缺陷和不同宽厚比等因素下的开口加劲肋板的稳定极限承载力。     

轴心受压开口薄壁构件弹塑性屈曲荷载的统一计算方法

通过分析构件截面上应变与轴向力间的关系，以构件轴向应变为基本参数，提出了轴心受压开口薄壁构件的弹塑性屈曲荷载统一计算方法，给出了轴压构件的弯曲屈曲、扭转屈曲、弯扭屈曲等屈曲荷载的弦截法迭代格式，可应用于H形、T形、L形、十形截面等不同开口形式的轴压构件屈曲荷载计算，并可考虑具有残余应力的弹塑性本构关系。该方法以无残余应力的弹性屈曲荷载对应的轴向应变作为初始值，根据不同屈曲形式对应的非线性方程计算弦截区间点的函数值，进行弦截法迭代计算，得到弹塑性构件的临界轴向应变，进而获得屈曲荷载等信息。该方法采用的弦截法收敛速度快、计算量小、无需嵌套循环，可有效解决两端铰接轴心受压开口薄壁构件的弹塑性屈曲快速计算问题，便于工程应用。     

非弹性屈曲下蜂窝钢梁的弯矩梯度因子

蜂窝钢梁的抗弯承载力受局部和整体失稳影响。使用有限元法研究混合屈曲模式下蜂窝钢梁的非弹性性能,建立一个考虑弯扭或畸变屈曲和横截面局部化变形之间相互作用的三维的非线性有限元模型,并根据现有研究文献中的可用结果进行验证。研究包括受三种不同荷载(跨中荷载、均布荷载和端弯矩)作用的简支梁,通过参数分析,从而评估不同几何参数对蜂窝钢梁非弹性稳定性的影响。这些参数包括钢梁横截面尺寸、翼缘宽度和厚度、腹板高度和厚度、开孔的形状和间距。介绍模拟研究中考虑各种尺寸的不同屈曲模式所对应的弯矩梯度因子。研究结果有望帮助更深入地研究蜂窝钢梁的性能,并准确预测弯矩梯度因子和这种特殊钢梁的抗弯承载力。     

带裂缝受压或受拉薄板的屈曲数值分析

板受压时通常发生屈曲破坏,尤其是当板厚与板的其他尺寸相比十分小时,这种破坏模式常先于强度破坏。受拉情况下也可能发生屈曲破坏,尤其是带裂缝板沿压应力方向,在缺陷周围经常发生局部屈曲现象。通过考虑各种几何、力学和边界特性,对受拉和受压状态下,各种带裂缝矩形弹性薄板的屈曲现象进行分析。简略回顾了板的屈曲破坏,采用有限元方法,进行几个参数分析,通过改变几何和力学参数,确定受压或受拉状态下的临界荷载因子。对不同的裂缝长度、裂缝方向和材料的泊松系数以及通过变化板的边界条件,确定屈曲临界荷载因子。借助几何非线性分析,考虑裂缝界面之间的作用,对裂缝的构造进行研究,以有效掌握整体结构的性能。针对各种受限带裂缝受压或受拉板的屈曲破坏中提参数的敏感性,给出计算结果的简图,得出一些实用的结论。     

对边弹性支承夹层玻璃板剪切屈曲分析

玻璃板与框架之间采用结构胶粘接形成的线支承连接,会因结构胶的弹性约束效应而影响玻璃板的剪切屈曲行为.本文通过有限元模拟研究了对边弹性支承夹层玻璃板在面内剪切荷载作用下的屈曲响应,分析了玻璃板长宽比、结构胶面内约束刚度、垫块几何尺寸及垫块弹性模量对夹层玻璃板剪切屈曲的影响规律.在理想简支、固支边界板件受剪屈曲临界荷载计算公式的基础上,引入考虑边界弹性约束刚度与板件厚高比的参数β,提出了对边弹性支承夹层玻璃板的剪切屈曲系数计算公式.经与工程常用夹层玻璃板的剪切屈曲临界荷载有限元分析值对比,表明计算公式安全可靠,可为工程应用提供参考.     

矩形开口对吸收塔结构非线性屈曲特性影响分析

为了分析矩形开口参数对于吸收塔结构稳定性的影响规律,以一实际在建吸收塔结构为研究背景,基于参数化模型的正交试验,采用有限元软件ANSYS对比分析了不同开口参数下吸收塔柱壳结构的非线性屈曲特性。结果表明:开口角度对于结构的影响较其他参数大,开口角度小于90°时,结构的非线性屈曲极限荷载下降趋势较为明显,超过120°后,降幅趋于缓和,壁厚25 mm工况下,90°开口时结构的非线性屈曲极限荷载较0°开口时下降91%,120°开口时较0°开口时下降95.2%;结构的非线性屈曲极限荷载随着矩形开口高度的增加而逐渐减小,但开口位置对于结构稳定性的影响在整个过程中近似呈线性变化。     

非均匀受压矩形钢管混凝土局部弹性屈曲分析

应用不同的特征函数描述了矩形板在非均匀压力作用下的屈曲形态,解决了采用三角级数为屈曲函数模拟非均匀受压荷载作用下单侧表面约束矩形板件屈曲模态的不对称问题;通过伽辽金法建立屈曲控制方程组,分析了非均匀荷载作用对矩形钢管混凝土构件局部弹性屈曲性能的影响。结果表明:钢管屈曲系数随着不均匀荷载梯度α增加而增大,纯弯作用下（α=2）的板件弹性屈曲荷载特征值约为轴压作用下的6倍;钢板的宽厚比限值随不均匀加载梯度α的增大而增加;非均匀荷载作用下非加载边固支约束板件的屈曲系数明显大于简支约束的板件。     

受压或受弯开孔薄板的弹性屈曲性能

开发、论证并总结了一组闭合公式,可以估算在弯矩或压力作用下,板的单个或多个开孔对其临界弹性屈曲应力的影响。公式适用于四边简支和三边简支的板(这在设计中又称为加劲板和非加劲板)。由于有限壳单元特征值屈曲分析需要运用商业有限元程序,而这些程序又不是专为结构分析而开发的,不能很方便地用于工程设计,所以可以采用这些公式作为这种屈曲分析方法的简化替代。这些公式的形式与板稳定性近似分析的经典形式相似,并通过有限壳元对其进行了参数分析并验证。有限元参数分析证实了开孔可能会导致板产生独特的屈曲模式,开孔的几何尺寸和间距可能会增加或者减少板的临界弹性屈曲应力。这些公式及其使用限制可适用于工程中通常采用的开孔形状、位置和间距,同时研究也指出,若需得到足够精确的计算,则还是有必要采用壳单元的有限元分析。     

全受压和局部边缘受压下有裂纹薄板屈曲的试验和数值研究

受压下薄钢板经常发生屈曲失效,尤其当薄钢板存在一些如开口和裂纹等缺陷时。这种失效模式先于强度失效。给出了轴压下有裂纹板的屈曲荷载的试验结果和数值结果。为此,采用1200A铝合金制作成矩形板,且板的中心有斜裂缝。在试验和数值研究中,分析了裂缝的长度和方向、板的厚度和长宽比的影响。对两种不同的支撑形式和荷载条件(如:局部边缘荷载和支撑)的影响进行研究。最后,将试验结果与数值结果进行对比。     

均匀剪力作用下无加劲肋的细长曲面板的屈曲和后屈曲性能

研究平面内剪力作用下曲面板的屈曲和后屈曲性能。回顾经典的弹性屈曲分析,通过对几何和材料非线性的分析,模拟了弹塑性后屈曲性能、及曲率参数和长宽比的影响。通过各种不同大小和级别的缺陷的影响分析,研究缺陷敏感度。随着曲率的增大,弹性临界荷载增大,并且产生不稳定屈曲现象,以及使后屈曲承载力储备减少。微小的初始缺陷都会引起较大曲率的曲面板的初始屈曲,但是几乎不会影响板的极限承载力。     

Elastic buckling of uniaxially loaded skew plates containing openings

The paper is concerned with elastic buckling behavior of uniaxially loaded skew plates with openings. Simply supported and clamped plates subject to uniaxial compression in the longitudinal direction are studied. Two different shapes of openings, circular and skew of different sizes, are considered. The finite element software package ABAQUS has been employed to analyze the plates. Effects of parameters such as skew angle, size, shape and position of openings and aspect ratio of the plates are examined. Results are presented in the form of plots showing the variation of buckling coefficient against the parameters studied.     

Inelastic initial local buckling of skew thin thickness-tapered plates with and without intermediate supports using the isoparametric spline finite strip method

In this paper, skew isotropic plates subjected to in-plane loadings are analyzed using a stability analysis based on the isoparametric spline finite strip method, which includes inelasticity. Using this method, the initial inelastic local buckling of skew plates with or without intermediate line supports is studied based on Ramberg–Osgood representation of the stress–strain curve using the deformation theory of plasticity. Stiffness and stability matrices are formulated by energy expressions using the small deflection theory. The effect of tapered section on the local buckling of skew plates is taken into account. Finally, the inelastic local buckling loads of these plates are obtained and the results are compared with known solutions in the literature.     

Buckling analysis of skew laminate plates subjected to uniaxial inplane loads

Elastic stability of skew composite laminate plates subjected to uniaxial inplane compressive forces has been studied. The critical buckling loads of the skew laminate plates are carried out by the bifurication buckling analysis implemented in finite element program ABAQUS. The effects of skew angles, laminate layups, plate aspect ratios, plate thicknesses, central circular cutouts, and edge conditions on the buckling resistance of skew composite laminate plates are presented.     

Thermal postbuckling of laminated composite skew plates with temperature-dependent properties

Thermal postbuckling and consequently, the role of temperature dependence of material properties on the thermal postbuckling behavior of laminated composite skew plates have not been addressed in literature. Hence, this problem is investigated here. The plate governing equations are based on the first-order shear deformation theory (FSDT) and the geometrical nonlinearity is modeled using Green’s strain tensor in conjunction with the von Karman assumptions. Since the problem is geometrically and physically nonlinear, the differential quadrature method (DQM) as an accurate, simple and computationally efficient numerical tool is adopted to discretize the governing equations and the related boundary conditions. Then, a direct iterative method is employed to obtain the critical temperature (bifurcation point) and consequently the nonlinear equilibrium path (the postbuckling behavior) of symmetrically laminated skew plates. After validating the formulation and the method of solution, the effects of temperature dependence of the material properties on the postbuckling characteristic of laminated skew plates with different skew angle, boundary conditions, length-to-thickness ratio, number of layers and ply layout are investigated.     

Vibration and buckling of plates with mixed boundary conditions

This paper deals with the vibration or buckling of thin plates with either mixed boundary conditions or discontinuous boundary conditions using the spline element method.

To demonstrate the accuracy of the method, several examples are solved, and results are compared with those obtained by other numerical methods. The effects of partial rotational constraints and angles of skew on frequencies and buckling loads of isotropic skew plates are also investigated.     

A differential quadrature nonlinear free vibration analysis of laminated composite skew thin plates

Using a differential quadrature (DQ) method, large amplitude free vibration analysis of laminated composite skew thin plates is presented. The governing equations are based on the thin plate theory (TPT) and the geometrical nonlinearity is modeled using Green's strain in conjunction with von Karman assumptions. To cause the impact due to nonlinear terms more significant, in-plane immovable simply supported, clamped and different combinations of them are considered. The effects of different parameters on the convergence and accuracy of the method are studied. The resulted solutions are compared to those from other numerical methods to show the accuracy of the method. Some new results for laminated composite skew plates with different mixed boundary conditions are presented and are compared with those obtained using the first order shear deformation theory based DQ (FSDT-DQ) method. Excellent agreements exist between the solutions of the two approaches but with much lower computational efforts of the present DQ methodology with respect to FSDT-DQ method.     

方形预应力板开方形洞口加固估算公式的推导

通过建立有限元模型进行计算 ,总结出了方形板开方形洞口粘钢加固的估算公式     

加劲肋截面对加劲板力学性能的影响

加劲肋截面形式对加劲板的力学性能有重要影响。文中以某工程中承受平面外均布荷载的加劲板为研究对象,采用有限元方法,分别研究了不同加劲板母板厚度、不同加劲肋截面惯性矩对加劲板力学性能的影响。结果表明:采用角钢加劲肋提高加劲板抗弯性能是最有效的,等边角钢加劲肋较不等边角钢加劲肋能更好地的提高加劲板的抗弯性能,工字钢和槽钢加劲肋改善加劲板抗弯性能的能力是相近的。     

Buckling of laminated skew plates

A general high precision triangular plate bending finite element has been extended to the buckling analysis of laminated skew plates. This procedure involves development of the transformation matrix between global and local degrees of freedom for nodes lying on the skew edges and suitable transformation of the element matrices. The accuracy of the present formulation has been verified against literature values. New results are obtained for antisymmetric angle-ply and cross-ply laminated skew plates. In this analysis, the critical buckling loads for different skew angles with various lamination parameters, such as number of layers, fibre orientation angle, different boundary (simply supported, clamped) and loading (uniaxial, biaxial) conditions, have been presented.     

钢板剪力墙大矩形开孔的加固方法

对在建筑中作为门窗的钢板剪力墙的大矩形开孔加固的非线性性能进行研究。对一些开孔和未开孔的钢板剪力墙进行数值分析:1)用分析结果对开孔的钢板剪力墙的性能进行描述;2)研究开孔处局部边界梁结构的开孔特性、大小和开孔处任意边的填充板厚度所带来的影响;3)调查开孔所带来的系统强度和刚度的改变。结果显示,根据AISC20《钢结构设计规范》来解决开孔处上、下梁的设计并不完善。对局部边界梁结构使用略厚或略薄的内填充板将会改变整体的屈服顺序。显而易见,尽管不同开孔所需的不同局部边界梁结构的大小会对其有一定的影响,开孔加固的类型﹑位置﹑形状并不会影响整体强度。在不同的钢板剪力墙中使用开孔加固可以增加其极限强度和刚度,而略微减小延性比。