弹性支承上简支约束长矩形薄板面内剪切作用下屈曲行为分析

近年来,钢-混组合结构在工程中广泛应用,薄壁钢板在组合结构承载过程中易发生局部屈曲。矩形钢管混凝土作为结构梁时,薄壁钢板易发生弯剪局部屈曲;薄壁钢-混凝土组合墙在抵抗水平作用时,钢板也易发生剪切屈曲。组合结构中充当支承的材料除了刚性混凝土,还有轻质弹性材料。论文采用Rayleigh-Ritz法,对弹性支承上简支约束长矩形薄板面内剪切受力条件下的屈曲行为进行分析研究,建立了满足上述边界条件的板的弹性屈曲计算公式。计算结果表明:该理论计算方法对于长矩形薄板(长宽比大于2)的屈曲具有广泛适用性。     

层状地基上预应力弹性板的竖向振动特性研究

基于解析层元法和经典弹性薄板理论,提出了一种求解层状地基与预应力弹性板竖向动力相互作用的计算方法.从地基的基本解和弹性薄板动力方程出发,借助Hankel积分变换,并结合地基与弹性板在接触面上的相容条件,得到变换域内地基与弹性板的动力耦合方程.通过求解耦合方程和数值逆变换,得到频域内预应力弹性板的位移解.与已有文献的结果...     

层状地基上预应力弹性板的竖向振动特性研究

基于解析层元法和经典弹性薄板理论,提出了一种求解层状地基与预应力弹性板竖向动力相互作用的计算方法。从地基的基本解和弹性薄板动力方程出发,借助Hankel积分变换,并结合地基与弹性板在接触面上的相容条件,得到变换域内地基与弹性板的动力耦合方程。通过求解耦合方程和数值逆变换,得到频域内预应力弹性板的位移解。与已有文献的结果进行对比,验证提出方法及计算程序的正确性及有效性。最后,通过算例分析,探讨了板–土刚度比和板径向预应力对预应力弹性板竖向动位移的影响。     

刚性基底的周边不同边界约束矩形板面内纯剪作用下屈曲研究

基于刚性基底的矩形板面内受压作用下的单向屈曲问题已有一些研究成果,而基于刚性基底的矩形板面内剪切受力条件下的单向屈曲问题国内尚无相关文献报道。通过对基于刚性基底的周边不同约束矩形板面内剪切受力条件下的单向屈曲行为的分析研究,采用Rayleigh-Ritz变分法建立了满足上述边界条件的板的弹性屈曲计算理论,得出简支边界薄板的临界屈曲系数κcr=7. 2,与国外相关文献采用有限单元法推导的κcr值偏差为7. 8%,得出固支边界薄板的临界屈曲系数κcr=13. 06,与国外相关文献采用微分方程法推导的κcr值偏差为7. 4%。研究结果表明:该计算理论有广泛的适用性。     

新型单元在结构共同作用分析中的应用

在平面矩形单元和板单元的基础上推导了考虑法向、切向地基反力的弹性厚薄板通用单元,将它应用于上部结构、基础和地基的共同作用分析程序中,并将所得结果与常规薄板理论计算结果进行比较,验证了厚薄板通用元的正确性。     

基于板-梁理论的集中荷载下带侧向弹性支撑矩形钢管混凝土翼缘工字形梁的弯扭屈曲分析

基于板-梁理论和能量变分原理,建立集中荷载下跨中布置侧向弹性支撑的矩形钢管混凝土翼缘工字形简支梁的弯扭屈曲总势能方程,其中位移和转角模态试函数选用6项三角级数形式.引入无量纲参数并依据势能驻值原理,获得弯扭屈曲无量纲临界弯矩解析解.采用1stOpt数学优化分析软件,拟合矩形钢管混凝土翼缘工字形简支梁无量纲临界弯矩计算公...     

文克尔地基上四边自由矩形带肋梁板的计算

弹性地基上自由边矩形板问题是Kirchhoff薄板理论的难题之一，文献[1]采用叠加法得到了该问题的精确解，文献[2]采用能量法得到了该问题的近似解。由于肋梁的存在，弹性地基上带肋梁的矩形板问题比平板问题更复杂。本文采用里兹法得到求解该问题的一个近似方法。1 弹性地基上带肋梁板的平衡方程及应变能泛函弹性地基上的矩形平板的平衡微分方程为： （1）式中 D—板的刚度，E为板的弹性模量，h为板的厚度，ν为板的泊松比；w—板的竖向挠度；p—为外荷载；k—文克尔系数。图1为带肋梁矩形板的结构简…     

弹性矩形板与弹性地基共同作用的简化计算法

 将基础板视为弹性板, 通过对四角点支承、四边自由矩形板按弹性薄板考虑, 求出其解析解, 然后与现有的弹性地基模型相结合, 得出弹性地基上弹性薄板与土共同作用的半解析解。给出了一些算例的结果。     

横向变温下四边简支矩形薄板的解析解

根据横向变温作用下各向同性材料弹性矩形薄板的平衡微分方程和边界条件,通过试取挠度函数,推导了四边简支情况下的挠度及内力计算公式,从而为该类板在温度作用下的结构计算提供了理论基础。     

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。     

Concrete panel thickness demand for the design of composite steel plate shear wall

Composite steel plate shear walls (C‐SPWs) are composed of an infill steel plate and reinforced concrete encasements. With an adequate thickness, the concrete encasement can effectively prevent the premature buckling of the infill steel plate. Researchers have provided nonconservative concrete thickness demands through analyses of approximate elastic buckling, for which the analytical model is too simplistic to simulate C‐SPW buckling. In this paper, the buckling of C‐SPW is addressed using a nonlinear finite element method. To assist this method, a formula for the buckling strength of C‐SPW is theoretically developed. Utilizing the results of nonlinear finite element analysis on C‐SPW, the effects of concrete panel thickness, concrete elastic modulus, infill steel plate thickness, panel aspect ratio, and stud spacing on the infill steel plate buckling are analyzed, and the critical drift ratio corresponding to the buckling of the infill steel plate is obtained. According to the criterion that the C‐SPW will not buckle until its drift ratio achieves the drift limit (0.4%), the minimum concrete panel thicknesses demands are captured from finite element analysis. Fitting these predicted minimum concrete thicknesses, an available formula is proposed for the concrete thickness demand in the design of C‐SPW.     

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。     

Elastic/plastic buckling of a composite flat plate subjected to uniform edge compression

A theoretical approach, based on the plastic theory, has been developed for studying the elastic/plastic buckling behavior of a simply supported rectangular anisotropic plate subjected to edge compression. The said approach was employed to determine the critical buckling stresses of three different types of fiber reinforced composite plates, namely, carbon epoxy, glass epoxy and boron aluminum plates. Since the proposed approach is for a preliminary prediction of critical buckling loads of composite plates, the results obtained are deemed acceptable compared with those obtained by other authors experimentally.     

Elastic stability of uniformly compressed plates perforated in triangular patterns

Critical elastic buckling load of uniformly compressed isotropic plates perforated in equilateral triangular patterns was investigated using FEM. Stiffened and unstiffened square and rectangular elements with wide ranges of hole diameter-to-spacing ratio and plate slenderness were studied. The effect of perforations on the critical elastic buckling load was determined. Design formulas for predicting critical elastic buckling stress based on reduction coefficient approach and equivalent thickness approach were developed using multiple nonlinear regression analysis of FEM results. The obtained critical elastic buckling stress reductions and developed formulas were verified by comparison with results available in literature and with an extensive database of FEM results.     

不同面外约束下带缝钢板剪力墙的抗剪性能研究

采用有限元软件ABAQUS,考虑几何非线性和面外初始缺陷的影响,对比分析钢筋混凝土板约束、刚性板约束以及无面外约束的带缝钢板剪力墙在水平荷载作用下的刚度、抗剪承载力、延性和耗能能力,并研究面外约束对带缝钢板的应力分布和面外屈曲的影响。结果表明:钢筋混凝土板可以抑制带缝钢板的弹性屈曲,降低带缝钢板的拉力带效应,提高带缝钢板剪力墙的延性、抗剪承载力和耗能能力。为了使钢筋混凝土板能更好地约束带缝钢板的面外屈曲,建议在剪力墙的小变形阶段,混凝土板不参与抗剪。     

Local buckling of steel plates in rectangular CFT columns with binding bars

This paper presents a theoretical study on the elastic local buckling of steel plates in rectangular concrete-filled steel tubular (CFT) columns with binding bars under axial compression. It is assumed that the unloaded edges of the steel plate are elastically restrained against rotation, whereas the loaded edges are clamped. Based on the energy method, the formulas for elastic local buckling strength of the steel plate in rectangular CFT columns under axial compression are derived, which are calibrated with the experimental results. Then the formulas are employed to study the elastic local buckling of steel plates in rectangular CFT columns with binding bars under axial compression. It is shown that the binding bars can increase the local buckling coefficient, which results in improvement of the capacity of the steel plate to resist local buckling. Finally, appropriate spacing of binding bars, appropriate limitation for aspect ratio and corresponding appropriate limitation for width-thickness ratio are suggested for rectangular CFT columns with binding bars under axial compression.     

Two-dimensional upheaval buckling of a heavy sheet

A large elastic sheet with a significant self-weight subject to biaxial in-plane compression while lying on a rigid horizontal plane may buckle. The buckles, circular areas which lift away from the rigid subgrade, are essentially a plate (two-dimensional) phenomenon, analogous to the widely discussed one-dimensional upheaval buckling of beams. It is shown that plate upheaval is relatively insensitive to subgrade friction, a fact which may simplify design against such buckling.     

火灾下钢筋混凝土结构热弹塑性变形分析

为了研究钢筋混凝土结构在火灾作用下的力学性能,利用弹塑性理论,根据材料不同的屈服法则,分别给出了钢筋和混凝土材料考虑温度变形和徐变变形热弹塑性问题的增量本构方程。考虑钢筋和混凝土力学性能随温度的变化,编制程序对钢筋混凝土简支板进行了非线性分析,并利用相关文献的试验结果,对本构方程的正确性和适用性进行了验证。对火灾作用下1榀单层单跨钢筋混凝土框架进行了非线性分析,并给出了部分节点位移随受火时间的变化规律。结果表明,钢筋混凝土结构在高温下会产生很大变形,钢筋混凝土框架梁柱节点位移随受火时间变化的曲线并不是呈单调变化趋势,有拐点存在,梁柱节点竖向位移值小于梁跨中节点值。     

Finite element analysis of linear plates buckling under in-plane patch loading

The elastic buckling load is physically important in design because it is actually the critical step in the changing plate configuration that will eventually lead to complete failure. The present work investigates the problem of linear buckling of simply supported thin plates subjected to patch compression. In order to satisfy the boundary conditions in a rigorous way, the authors chose the finite element method using the exact stress distribution throughout the plate.In the present paper, the stability problem treated using the total energy is briefly outlined. The plate modelling is made by means of an eight noded rectangular element and a reduction of variable strategy is applied to estimate the number of degrees of freedom leading to little or no loss in seeking solution accuracy.The buckling coefficient is determined for different load cases applied to a range of plate with various edge ratios. The achieved results are summarised through different graphs representing variation of the buckling coefficient against the plate ratio for each load case treated. A comparison with previous works is made. Finally, it is shown that the resolution of the plate buckling problem using true stress distribution with the finite element method leads to a good agreement with results previously obtained by means of analytical methods using an exact stress distribution.     

矩形钢管混凝土壁板的屈曲后强度

为研究矩形钢管混凝土壁板的屈曲后强度,根据平板的弹塑性屈曲理论并考虑残余应力的影响,确定了板件发生塑性屈曲、弹塑性屈曲和弹性屈曲的正则化界限宽厚比。采用试验验证的有限元模型进行了宽厚比为20～150、钢材屈服强度为275～960 MPa的矩形钢管混凝土壁板局部屈曲分析,以界限宽厚比为控制点,根据有限元结果拟合出了矩形钢管混凝土壁板的有效宽度计算式。研究结果表明：弹性屈曲板件的屈曲后强度提高程度显著高于弹塑性屈曲板件;屈曲后强度的提高程度与钢材屈服强度无明显相关性;与无面外约束钢板相比,混凝土的单侧约束作用可使板件的屈曲后强度普遍提高约50%;提出的矩形钢管混凝土壁板的正则化界限宽厚比和有效宽度计算式与试验结果吻合较好,有效宽度试验值比所提公式计算值平均增大7.2%,标准差为0.091。