刚架几何非线性无网格法分析

本文以钢框架结构为研究对象,在非线性连续介质力学的有限形变理论的基础上,通过最小二乘法,采用无网格伽辽金法推导出梁柱几何非线性刚度矩阵,建立了相应的无网格法离散化系统方程,针对一榀典型钢框架,给出了其几何非线性无网格法分析结果并与有限元分析结果进行了对比,验证了本文方法的实用性和可靠性。     

斜向槽钢加劲钢板剪力墙弹性剪切屈曲研究

通过对剪切作用下的闭口斜加劲钢板剪力墙进行有限元弹性屈曲分析,研究了肋板刚度比和抗扭抗弯刚度比对斜向槽钢加劲钢板剪力墙剪切屈曲性能及其加劲门槛刚度的影响。通过有限元分析,得到了斜向加劲钢板剪力墙临界剪切屈曲应力随内填板跨高比和加劲肋抗扭抗弯刚度比变化的关系曲线。考虑加劲肋对内填板加劲边转动约束,提出了第二门槛刚度,并给出了具有良好精度的斜向槽钢加劲钢板剪力墙的门槛刚度及第二门槛刚度计算公式。研究结果表明,受压型加劲肋对加劲板的临界剪切屈曲应力提高明显,随肋板刚度比的增大,加劲板的剪切屈曲应力增大,而受拉型加劲肋对板的屈曲荷载提高有限;当肋板刚度比达到第二门槛刚度时,加劲肋可以完全约束加劲边的面外位移和转动。当提高加劲肋的抗扭抗弯刚度比时,能够有效降低加劲肋的门槛刚度,因此,建议加劲肋的抗扭抗弯刚度比不低于0.307。     

斜向槽钢加劲钢板剪力墙弹性剪切屈曲研究

通过对剪切作用下的闭口斜加劲钢板剪力墙进行有限元弹性屈曲分析,研究了肋板刚度比和抗扭抗弯刚度比对斜向槽钢加劲钢板剪力墙剪切屈曲性能及其加劲门槛刚度的影响。通过有限元分析,得到了斜向加劲钢板剪力墙临界剪切屈曲应力随内填板跨高比和加劲肋抗扭抗弯刚度比变化的关系曲线。考虑加劲肋对内填板加劲边转动约束,提出了第二门槛刚度,并给出了具有良好精度的斜向槽钢加劲钢板剪力墙的门槛刚度及第二门槛刚度计算公式。研究结果表明,受压型加劲肋对加劲板的临界剪切屈曲应力提高明显,随肋板刚度比的增大,加劲板的剪切屈曲应力增大,而受拉型加劲肋对板的屈曲荷载提高有限;当肋板刚度比达到第二门槛刚度时,加劲肋可以完全约束加劲边的面外位移和转动。当提高加劲肋的抗扭抗弯刚度比时,能够有效降低加劲肋的门槛刚度,因此,建议加劲肋的抗扭抗弯刚度比不低于0.307。     

钢板剪力墙任意布置单侧加劲肋的等效刚度

对任意布置纵向单侧加劲肋的钢板剪力墙单向轴压下的屈曲性能进行研究。采用隔离体分析法,把加劲肋和被加劲钢板离散成独立个体进行受力分析,考虑加劲肋扭转和剪切变形的影响,同时加劲肋和钢板在连接线处需满足变形协调条件,求得单侧加劲板单向轴压下的屈曲临界方程,对比双面对称加劲板的屈曲临界方程,获得单侧加劲肋等效为双面对称加劲肋的等效抗弯刚度和等效抗扭刚度的解析表达式,进而获得被加劲板参与加劲肋工作的有效宽度表达式。与有限元模拟结果进行分析比对表明,公式具有良好精度,适用于任意开口和闭口截面的单侧加劲肋板。通过单侧加劲肋的等效刚度表达式,可以把单侧加劲问题转化为双侧加劲问题。     

槽钢加劲钢板剪力墙受力性能研究

竖向槽钢加劲钢板剪力墙由内嵌钢板、边缘构件和墙板两侧对称布置的竖向槽钢加劲肋组成。槽钢加劲肋具有较高的抗弯、抗扭刚度,可为墙板提供有效的面外约束和轴向支撑作用。利用有限元分析软件ABAQUS对槽钢加劲钢板墙进行屈曲分析和静力弹塑性分析,研究槽钢距边缘构件距离、钢板宽厚比、高厚比、肋板刚度比和柱刚度对钢板墙及边缘构件力学性能的影响。结果表明,槽钢加劲肋至边缘构件的距离主要影响钢板墙的平面外变形,对钢板墙屈曲应力和承载力的影响较小。槽钢加劲肋可以有效提高墙板的屈曲应力。随着宽厚比和高宽比的减小,结构的承载力和刚度均显著提高。增大肋板刚度比可提高钢板墙的初始刚度和屈曲应力,肋板刚度比应大于20。为避免边框柱变形过大或过早破坏,边框柱应具有足够的刚度,增大柱刚度可以提高钢板墙的初始刚度,减缓墙板刚度的退化。     

外伸端板加劲肋试验和有限元研究

为研究梁柱外伸端板螺栓连接中端板加劲肋对节点刚度和承载力的影响,对外伸端板加劲肋进行系统分析.给出三角形加劲肋较无限长矩形加劲板受拉强度效率系数的计算公式,并基于端板外伸加劲肋的传力及翼缘内外侧螺栓拉力均衡的考虑提出加劲肋形状和厚度的设计方法.对6个无加劲和3个加劲T形件连接节点进行试验研究,并对多个外伸端板连接节点模型进行有限元分析.研究结果表明,工程中常用加劲肋会过早屈服,起不到理想的加劲效果;推荐方法设计的端板加劲肋能够很好地满足<门式刚架轻型房屋钢结构技术规程>(CECS102:2002)所隐含的加劲肋使端板外伸部分由一边固支三边自由板变为两相邻边固支板的要求.     

外加盖板斜加劲薄钢板墙弹性屈曲性能分析

采用有限元软件ANSYS 15.0对多组外加盖板斜加劲薄钢板墙(CSW)模型进行弹性屈曲分析,研究盖板相似比、盖板高厚比、加劲肋高厚比及肋板刚度比等因素对CSW模型屈曲性能的影响,探讨提高CSW结构屈曲应力的方法,最终给出了CSW肋板刚度比的门槛刚度以及盖板高厚比的合理取值范围。     

无网格伽辽金法在热弹性薄板弯曲问题中的应用

用无网格伽辽金法研究了热弹性薄板的弯曲问题,由移动最小二乘法和虚位移原理得到热弹性板的近似场函数和刚度方程,编制相应的无网格法计算程序,并给出算例.结果表明了该方法可行,且具有广泛的工程应用前景.     

加劲肋对VV-SPSW剪切屈曲性能影响分析

采用有限元软件ANSYS10.0对多组VV-SPSW模型进行数值模拟,分析了肋板刚度比、加劲肋根数、加劲肋数量等对VVSPSW剪切屈曲性能的影响,并给出了VV-SPSW的加劲肋设计的合理建议,为同类工程问题的研究提供了参考依据。     

设纵向加劲肋后矩形钢管混凝土柱屈曲机制分析及构造建议

针对搜集的38根设肋试件的轴压试验结果,采用ABAQUS进行了有限元计算。计算结果表明,轴压承载力与试验轴压承载力误差在7%以内,破坏模式与试验破坏模式吻合较好。根据相关试验数据,对加劲肋的工作机理及受力状态进行了分析。分析结果表明,平板加劲肋截面抗弯刚度对试件承载力有明显的影响,应选取合适加劲肋抗弯刚度及截面尺寸,才能既使组合构件的承载性能得到有效发挥,同时用钢量得到合理优化;钢管屈曲模式受加劲肋刚度的影响较大,随着加劲肋刚度的增大,钢管板件逐渐由在板件横向的一个半波转变为两个半波;当加劲肋刚度达到临界刚度后,加劲肋截面面积不再影响钢管屈曲模式,但试件的轴压承载力随加劲肋面积的增大而增大。     

Bending analysis of folded plates by the FSDT meshless method

In this paper, a meshfree Galerkin method that is based on the first-order shear deformation theory (FSDT) will be introduced to analyse the elastic bending problem of stiffened and un-stiffened folded plates under different loadings and boundary conditions. Folded plates are regarded as assemblies of plates that lie in different planes. The stiffness matrices of the plates are given by the meshfree method. Employing the element concept, which is borrowed from the finite element method, and treating every plate as a big element, the global stiffness matrix of the whole folded plate is obtained by superposing the stiffness matrices of the plates. This is about the same for the analysis of stiffened folded plates. They are considered as assemblies of stiffened plates. The stiffness matrices of the stiffened plates are also given by the meshfree method. Superior to the finite element methods, no mesh is required in determining the stiffness matrices for the plates and the stiffened plates in this paper, which means time-consuming and accuracy-suffering remeshing is entirely avoided for problems such as large deformation or crack propagation in folded plates or stiffener position changes of stiffened folded plates. To demonstrate the accuracy and convergence of the method, several numerical examples are calculated by it and the finite element commercial software ANSYS. Good agreement is observed between the two sets of results.     

Free vibration analysis of cracked thin plates by quasi-convex coupled isogeometric-meshfree method

The free vibration analysis of cracked thin plates via a quasi-convex coupled isogeometric-meshfree method is presented. This formulation employs the consistently coupled isogeometric-meshfree strategy where a mixed basis vector of the convex B-splines is used to impose the consistency conditions throughout the whole problem domain. Meanwhile, the rigid body modes related to the mixed basis vector and reproducing conditions are also discussed. The mixed basis vector simultaneously offers the consistent isogeometric-meshfree coupling in the coupled region and the quasi-convex property for the meshfree shape functions in the meshfree region, which is particularly attractive for the vibration analysis. The quasi-convex meshfree shape functions mimic the isogeometric basis function as well as offer the meshfree nodal arrangement flexibility. Subsequently, this approach is exploited to study the free vibration analysis of cracked plates, in which the plate geometry is exactly represented by the isogeometric basis functions, while the cracks are discretized by meshfree nodes and highly smoothing approximation is invoked in the rest of the problem domain. The efficacy of the present method is illustrated through several numerical examples.     

A new meshless approach for bending analysis of thin plates with arbitrary shapes and boundary conditions

An efficient and meshfree approach is proposed for the bending analysis of thin plates. The approach is based on the choice of a set of interior points, for each of which a basis function can be defined. Plate deflection is then approximated as the linear combination of those basis functions. Unlike traditional meshless methods, present basis functions are defined in the whole domain and satisfy the governing differential equation for plate. Therefore, no domain integration is needed, while the unknown coefficients of deflection expression could be determined through boundary conditions by using a collocation point method. Both efficiency and accuracy of the approach are shown through numerical results of plates with arbitrary shapes and boundary conditions under various loads.     

弹性地基板的等参有限元法计算

提出了弹性半空间地基板的四节点和八节点等参元计算方法。该方法适用于弹性地基上不同形状的薄板或厚板的计算。算例表明，本文方法适应性强、精度较高，用较少的单元就能获得较好的结果。     

高强度螺栓外伸端板连接有限元模拟方法研究

高强度螺栓外伸端板连接节点可用不同的有限元方法进行模拟.对典型高强度螺栓外伸端板连接的ANSYS有限元模拟方法进行了比较研究,分别建立了T型件简单模型和复杂实例进行有限元分析,通过对比有限元单元数量、建模难易程度以及计算耗时等,分析了各种有限元模拟方法的特点.通过有限元结果与试验结果的比较,给出了一种建议的模拟方法.研究结果表明,直接粘贴方法虽然具有建模简单的优点,但是该方法由于过分放大了连接板系统的强度和刚度,因而基于该方法获得的应力和位移都比实际情况小;耦合螺孔节点方法虽然能比较接近的模拟连接节点受力性能,但该方法的最大问题是耦合节点处的应力和位移会发生畸变,与实际情况不符;预拉力加接触方法虽然建模较复杂,但计算结果最为合理,与实际连接节点受力情况吻合较好.     

任意基础板的有限元分析

假定基础板对地基的作用为一连续分布荷载 ,采用 16节点退化实体等参元对基础板进行有限元分析。实体退化等参元不仅能够比较精确地描述基础板的平面形状 ,而且特别适合于变厚度基础板的有限元分析。Winkler地基上的板和弹性地基上的板的数值算例表明 ,本文方法适用于厚、薄基础板的分析 ,且具有精度高、能够考虑地基水平刚度等优点     

Meshfree analysis of dynamic fracture in thin-walled structures

Analysis and reliability assessment of fracturing thin-walled structures is important in engineering science. We focus on numerical analysis of dynamic fracture of thin-walled structures such as pipes and pressure vessels. Instead of using finite element method, we propose meshfree method that has advantages because its higher order continuity and smoothness and its opportunities to model fracture in a simple way. Therefore, connectivity between adjacent nodes are simply removed once fracture criterion is met. The main advantage of our meshfree method is its simplicity and robustness.     

Buckling analyses of anisotropic plates and isotropic skew plates by the new version differential quadrature method

A new version differential quadrature method (DQM) has been proposed to obtain buckling loads of thin anisotropic rectangular and isotropic skew plates. The essential difference from the old version DQM is the introduction of two degrees of freedom for boundary points and from the existing differential quadrature element method (DQEM) is the determination of the weighting coefficients. The methodology is worked out in detail and a variety of buckling problems shown slow convergence earlier by Rayleigh-Ritz method with beam functions, including isotropic skew plates with various skew angles and anisotropic rectangular plates with simply supported or clamped boundary conditions, are solved by the proposed DQM. Numerical results indicate that fast convergence is achieved and excellent results are obtained by the proposed DQM.     

加劲板的计算方法研究

提出了一种板梁分开方法计算加劲板的理论模型，并用有限元法对该理论模型进行了几何非线性分析，与一些实验结果及一些解析解比较，得出了满意的结果。     

板壳结构非线性屈曲分析的修正拉格朗日法

本文采用退化曲壳有限单元,推导了板壳结构非线性有限元分析的、修正的拉格朗日法(Updated Lagrauge简称U.L.法,下同),并编制了非线性有限元程序.利用本文理论方法既可分析板壳的太变形问题,同时也可考虑材料进入非线性后的太应变问题.通过对一些板壳屈曲问题的分析对比,证明了本文理论方法的正确性和有效性.