屈曲约束支撑铰接框架足尺模型模拟地震振动台试验

对屈曲约束支撑铰接框架结构体系特点和抗震性能进行分析,并进行一个足尺屈曲约束支撑铰接框架结构模型模拟地震振动台试验研究。通过试验,分析不同强度地震作用下屈曲约束支撑铰接钢框架结构的动力特性、加速度反应、位移反应和破坏特征。振动台试验和研究结果表明:在强地震作用下(加速度峰值为1.20g),屈曲约束支撑交接框架结构层间位移角为1/100,屈曲约束支撑有明显的屈服变形,但没有发生屈曲现象,且整体结构中框架梁、框架柱仍保持弹性状态。理论和试验表明:屈曲约束支撑铰接框架结构可以在地震区使用。     

焊接空心鼓节点在单层网壳结构中的应用研究

通过对一具有足尺节点的单层球面网壳模型静力试验和非线性有限元计算 ,分析了焊接空心鼓节点的刚度对单层网壳结构受力性能的影响 ,研究了该类节点的网壳结构非线性计算模型的适用性 ,并对焊接球承载力进行了修正 ,对于焊接空心鼓节点在网壳结构中的推广应用有实际意义     

板锥柱面网壳结构的试验研究与有限元分析

为研究板锥网壳结构的实际承载能力和破坏全过程,了解结构的受力性能和整体刚度,对板锥柱面网壳结构进行模型试验研究。对试验模型的细部构造进行设计,确定上弦节点、下弦节点、支座节点、锥体成形及连接构造。对两纵边支承的试验模型在正常荷载工况和破坏荷载工况下进行加载试验,并采用ANSYS软件对试验模型进行非线性有限元分析。结果表明：板锥柱面网壳的整体刚度大,在正常荷载模式下,结构的变形很小,最大竖向位移与跨度的比值为1/3787,弦杆的受力主要是沿拱轴方向传递;在破坏荷载模式下,锥体的节点板连接处率先发生局部屈曲,之后焊点破坏,结构丧失承载能力。有限元与试验所得承载力最大误差为11%,破坏模式基本一致,所用有限元分析方法可靠。     

均布荷载下三角网格圆锥壳的临界屈曲荷载分析

利用统计回归技术和非线性有限元分析，研究三角网格锥壳的屈曲行为，用来分析研究的三角网格锥壳刚度相对均匀、承受的荷载均匀、边界条件也均匀：同时利用统计回归技术分析节点刚度对临界屈曲荷载的影响本编译自美国TEMCOR公司提供的有关资料。     

Experimental research and finite element analysis of plate-cone cylindrical reticulated shell

为研究板锥网壳结构的实际承载能力和破坏全过程，了解结构的受力性能和整体刚度，对板锥柱面网壳结构进行模型试验研究。对试验模型的细部构造进行设计，确定上弦节点、下弦节点、支座节点、锥体成形及连接构造。对两纵边支承的试验模型在正常荷载工况和破坏荷载工况下进行加载试验，并采用ANSYS软件对试验模型进行非线性有限元分析。结果表明：板锥柱面网壳的整体刚度大，在正常荷载模式下，结构的变形很小，最大竖向位移与跨度的比值为1/3787，弦杆的受力主要是沿拱轴方向传递；在破坏荷载模式下，锥体的节点板连接处率先发生局部屈曲，之后焊点破坏，结构丧失承载能力。有限元与试验所得承载力最大误差为11%，破坏模式基本一致，所用有限元分析方法可靠。     

板锥球面网壳结构稳定承载力性能的影响因素分析

影响板锥球面网壳结构稳定承载力性能的因素很多,其中主要有结构形式、矢跨比、板件材料等。首先介绍了板锥球面网壳的形式和分类,接着提出特征值屈曲分析和弧长法相结合是进行结构非线性屈曲分析的一种有效方法,通过算例,分析这三个影响因素对稳定承载力性能的影响程度,并得到一系列重要的结论。     

轴力作用下钢制盖板节点极限承载力计算

对轴力作用下钢制网壳盖板节点承载力进行了有限元分析,并通过盖板节点足尺试验验证有限元分析的正确性.改变有限元模型参数,计算数十个模型,基于分析结果得出轴力作用下钢制盖板节点的破坏模式.结果表明,盖板节点破坏模式有螺栓群抗剪破坏及盖板中心区域屈曲破坏两种.对结果数据进行拟合,得出钢制盖板节点在轴力作用下承载力计算公式.轴力作用下钢制盖板的极限承载力主要与螺栓的直径与数量、盖板的厚度和直径等因素有关,极限承载力由两种破坏模式所对应承载力的较小值确定.     

GFRP-钢屈曲约束支撑力学性能试验研究

提出GFRP-钢屈曲约束支撑的构造及其生产工艺。通过对4个GFRP-钢屈曲约束支撑足尺试件进行低周往复加载试验,研究GFRP-钢屈曲约束支撑的受力性能、破坏形态和耗能能力,考察外围约束单元中GFRP缠绕层厚度、缠绕角度和钢芯材形式对GFRP-钢屈曲约束支撑性能的影响。建立了GFRP-钢屈曲约束支撑的精细有限元模型,并对典型试验工况进行模拟。主要研究成果如下:1GFRP-钢屈曲约束支撑由钢芯材和GFRP拉挤型材通过缠绕工艺组合而成,容易实现工业化生产;2合理设计的GFRP-钢屈曲约束支撑的力学性能稳定,滞回曲线饱满,耗能性能优良;3增加外围约束单元中GFRP缠绕层厚度有利于提高GFRP-钢屈曲约束支撑的性能;4改变外围约束单元中GFRP缠绕角度对支撑性能无显著影响;5相对于一字形截面钢芯材,十字形钢截面芯材对外围约束单元的局部挤压更轻微,表现出更好的力学性能;6精细有限元模型可有效模拟GFRP-钢屈曲约束支撑的力学行为,模型精度较好。     

用于叠合板的钢筋桁架施工阶段屈曲探析

采用非线性有限元分析结合足尺试验的方法,对国内常用钢筋桁架类型进行施工阶段的屈曲分析。通过对12个桁架组合梁模型的计算,探讨国内外常用钢筋桁架受力模式的区别,确定了A型钢筋桁架的屈曲失效模式,及钢筋桁架高度对组合梁的刚度和极限承载力的影响。分析结果用于计算钢筋桁架上弦杆的屈曲长度和计算长度系数μ。     

冷弯薄壁型钢与混凝土组合节点抗震性能试验研究

结合某试点工程的要求 ,进行了冷弯薄壁型钢与混凝土组合节点在低周循环荷载下的足尺模型拟静力试验研究。在较详细阐述试验过程的基础上 ,结合试验现象阐明两种不同构造节点的循环塑性屈曲破坏、循环塑性累积破坏模式 ,并提出改进建议     

Experiments on conical shell reducers under uniform external pressure

In previous studies, a proliferation of research work has been undertaken on the buckling behavior of shell structures particularly conical shells. Nonetheless, no experimental studies are found in the literature on the buckling of a full and real configured model of a slender shell reducer with two cylindrical end boundaries. To this end, buckling behavior of three conical shell reducers under uniform peripheral pressure was investigated and evaluated experimentally in this paper. In addition, relevant FE simulations as well as theoretical predictions were taken into account to compare buckling load and modes of deformation. Derived results were aimed at generalizing the data for conical reducers in full scale within the range of this study.     

Buckling of fixed-roof aboveground oil storage tanks under heat induced by an external fire

This paper presents computational modeling and results of steel storage tanks under heat induced by an adjacent fire. In this research, modeling is restricted to the structural behavior of the tank, with emphasis on thermal buckling of the shell. Two tanks that buckled under a huge fire in Bayamón, Puerto Rico in 2009, are investigated in detail: a small tank with a self-supported conical roof, and a large tank in which the conical roof is supported by a set of rafters and columns. For a tank that is empty, the results show that a relatively low temperature is enough to produce static buckling of the shell. In pre-buckling states, the cylindrical shell has thermal expansion; at the critical state the displacements reverse and inwards displacements are observed at advanced post-buckling states. Parametric studies are performed to understand the influence of the shell thickness, the level of fluid stored in the tank, the area affected by fire in the circumferential direction, and the temperature gradient through the thickness. The buckling modes are compared with real deflection of tanks that were affected by fire.     

谐波沉降下开顶罐的屈曲分析

研究有关谐波沉降下开顶罐的屈曲性能。首先,研究各种谐波数下开顶罐的极限谐波沉降和屈曲性能。结果显示受小波数影响的上壳体发生屈曲,而受大波数影响时则在壳体的其他地方发生屈曲。随着谐波数的增加,在壳体底部也出现越来越多的屈曲点。此外,对开顶罐来说,受小波数影响时其极限谐波沉降大大降低,而受大波数影响时其极限谐波沉降降低极少。对开顶罐的屈曲性能进行数值研究,考察高径比(h/r)和径厚比(r/t)的影响。可知:在某种特定的谐波数下,极限谐波沉降与高径比(h/r)为单调递减的关系。同样的,随着谐波数的增加,极限谐波沉降的降低变化越来越小。而在某种特定的谐波数下,极限谐波沉降与径厚比(r/t)也为单调递减的关系。此外,随着谐波数的增加,极限谐波沉降的降低变化也越来越小。最后,将开顶罐和锥形顶罐的屈曲结果进行比较。结果显示,受小波数影响的开顶罐比不受锥形顶约束的锥形顶罐更能承受大的谐波沉降。然而,受大波数影响时,开顶罐与锥形顶罐的沉降持续能力有所不同。     

A numerical investigation of dynamic plastic buckling behaviour of thin-walled cylindrical structures with several geometries

In this study dynamic buckling behaviors of an aluminum alloy cylindrical shell with axial linear variable thickness, discontinuity and conical shaped have been numerically investigated for high velocity impact by means of finite element method. The validation of finite element model was provided by the results of previous studies in literature. Throughout study commerce finite element package program LS-DYNA3D was used and all simulations were fulfilled as explicitly. According to results obtained, the minor changes in the geometry are able to convert the dynamic plastic buckling into dynamic progressive buckling behavior. This study indicates that which of the dynamic buckling or progressive buckling mechanism will be dominant is sensitive to geometrical properties for cylindrical aluminum alloy shells under the high velocity impact.     

Buckling experiments on steel silo transition junctions: I: Experimental results

Large elevated steel silos for the storage of bulk solids generally consist of a cylindrical vessel above a conical discharge hopper supported on a cylindrical skirt. The cone–cylinder–skirt transition junction is subject to a large circumferential compressive force which is derived from the horizontal component of the meridional tension in the conical hopper, so either a ring is provided or the shell walls are locally thickened to strengthen the junction. Extensive theoretical studies have examined the buckling and collapse strengths of these junctions, leading to theoretically based design proposals. However, no previous experimental study on steel silo transition junctions has been reported due to the considerable difficulties associated with testing these thin-shell junctions at model scale. This paper presents the results of a series of tests on cone–cylinder–skirt–ring junctions in steel silos under simulated bulk solid loading. In addition to the presentation of test results including geometric imperfections and failure behavior, the determination of buckling modes and loads based on displacement measurements is examined in detail.     

Design and optimization of laminated conical shells for buckling

Optimum laminate configuration for the maximum buckling load of filament-wound laminated conical shells is investigated. In the case of a laminated conical shell, the thickness and the ply orientation (the design variables) are functions of the shell coordinates, influencing both the buckling load and the weight of the structure. Thus, optimization can be performed by maximization of the buckling load for a specific weight, or by minimization of the weight of the structure under the constraint of applied buckling load. Due to the complex nature of the problem a preliminary investigation is made into the characteristic behavior of the buckling load with respect to the volume as a function of the ply orientation.The exact buckling load is calculated by means of the computer code STAGS-A (Structural Analysis of General Shells [Almroth BO, Brogan FA, Meller E, Zele F, Petersen HT. Collapse analysis for shells of general shape, user's manual for STAGS-A computer code. Technical report AFFDL TR-71-8; 1973]) by adding a user written subroutine WALL, see Ref. [Goldfeld Y, Arbocz J. Buckling of laminated conical shells taking into account the variations of the stiffness coefficients. AIAA J 2004; 42(3):642–649]. The optimization problem is solved using response surface methodology.     

Behavior of stiffened liquid-filled conical tanks

Unreinforced steel conical-shaped containment vessels are frequently used in water tower applications. The failure of one of these structures in Fredericton, New Brunswick, Canada, several years ago, raises the question of whether there are adequate safety provisions for existing conical tanks. The aim of this investigation is to study the effect of welding rectangular-shaped longitudinal stiffeners to enhance the buckling capacity of existing conical tanks and to improve the design of new structures. The investigation is carried out numerically using an in-house developed shell element model that includes the effects of geometric and material non-linearities and accounts for geometric imperfections. The study focuses on two cases of tanks reinforced by longitudinal stiffeners in the lower region: the case of stiffeners free at their bottom edge, which would correspond to the retrofit of existing tanks; and the second having stiffeners anchored to the bottom slab of the tank, which can duplicate the situation of a new design. An extensive parametric study is conducted to assess the typical behavior of the two cases and to determine the critical imperfection shape that leads to the minimum buckling capacity of such type of stiffened shell structures. Finally, a comparison between the buckling capacity of unstiffened and longitudinally stiffened conical tanks that have the same volume of steel is conducted, revealing a major benefit of including stiffeners.     

Three-dimensional numerical analysis of geocell reinforced shell foundations

The effects of geocell reinforcement on the behavior of shell foundations were studied using PLAXIS 3D finite element software. For this purpose, conical and pyramidal geometries were adopted as shell foundations. The real honeycomb shape of geocell and rigid body behavior of shells were simulated in PLAXIS 3D. The numerical models for shell foundations and geocell reinforced foundations were separately validated using several laboratory studies in the literature. The validated models were extended to the shell foundations resting on geocell reinforced sandy beds. The inclusion of geocell-reinforcement provided more than 70% reduction in the settlement of pyramidal and conical shell foundations. The stress transferred to the sand beds were reduced and distributed a wider area compared to the unreinforced cases. The maximum improvement in the bearing capacity and the settlement were observed in the case of conical shell foundation. The effect of adopted geocell and shell configuration on the foundation behavior was also analyzed for realistic prototype foundation size.     

The effect of elastic foundations on the nonlinear buckling behavior of axially compressed heterogeneous orthotropic truncated conical shells

The buckling problem of a heterogeneous orthotropic truncated conical shell subjected to an axial load and surrounded by elastic media is analyzed based on the finite deformation theory. Using von-Karman nonlinearity, the governing equations of elastic buckling of heterogeneous orthotropic truncated conical shells surrounded by elastic media are derived. The governing equations are solved using superposition and Galerkin methods and obtained expressions for upper and lower critical axial loads. The influences of elastic foundations, heterogeneity, orthotropy and geometric characteristics on the upper and lower critical loads of conical shells with and without elastic foundations are studied in detail.     

Design procedure for stiffened water-filled steel conical tanks

Since the collapse of the steel liquid-filled conical tank located in Fredericton, Canada in December 1990, a concern has been raised about the safety of existing tanks. In a previous investigation, it was shown that welding longitudinal stiffeners to the bottom part of hydrostatically loaded conical tanks would provide a significant enhancement to the buckling capacity of this type of shell structure. In the current study, an attempt is made to develop a simple procedure that can be used in designing stiffened conical tanks. The procedure is based on the theory of orthotropic shells and design formulae for unstiffened tanks previously developed by Vandepitte.The study is conducted numerically using an in-house developed shell element model to simulate both the walls of the tank and the stiffeners. The study considers stiffening existing tanks and the design of newly stiffened ones. As the application of the orthotropic theory depends on the ratio between the stiffener spacing and the shell thickness, limiting values for such a ratio have been evaluated and are presented graphically. The orthotropic design procedure is then described and applied in two examples involving a retrofitted as well as a newly designed stiffened conical tanks.