铜筒仓转折环染的稳定设计准则

钢筒仓结构广泛应用于矿业、冶金、化工、电力、农业等诸多领域中的散料储存。圆形铜筒仓通常由仓筒、锥形漏斗及支承裙筒组成。在仓筒与漏斗的连接处通常设有一道环梁，以承受由漏斗壁上拉力的水平分力所产生的周向压力。常见的环梁形式包括环板形环梁、Ｔ形环梁以及角钢形环染。环梁在周向压力作用下的破坏模式包括塑性破坏、弹性屈曲以及塑性屈曲。近年来对于均匀支承环梁的屈曲及破坏强度已有了系统的研究，本将总结这些研究成     

温度作用下大直径钢筒仓热力耦合屈曲分析

落地式钢筒仓仓壁直接支承于混凝土环梁基础上,这种仓壁与基础的连接方式会使温度作用下筒仓根部产生显著的温度应力和变形,并对筒仓的屈曲性能产生影响.按照欧洲规范EN 1993-1-6推荐的5种壳体屈曲分析方法,分析太阳辐射作用下产生的非均匀温度场对大直径落地式平底圆柱钢筒仓稳定性的影响;并与均匀温度作用和无温度作用时筒仓的屈曲性能进行对比,得出不同温度作用对不同分析方法得到的筒仓屈曲模态和承载力的影响.最后通过参数分析得出缺陷的形式和幅值对钢筒仓屈曲的影响.     

带转折环梁的柱支承钢筒仓的结构行为研究

系统研究带转折环梁的柱支承钢筒仓(支柱终止于转折环梁下方)的结构行为。通过线性应力分析了解这类筒仓的应力和变形分布规律,通过线性特征值屈曲分析和几何非线性分析研究支承宽度和环梁截面尺寸对结构屈曲强度的影响。研究表明,支承宽度是影响结构屈曲强度的主要因素,而环梁截面尺寸仅对环梁局部屈曲有显著影响,对结构整体承载能力影响很小;由于环梁表现出稳定的后屈曲性能,以环梁屈曲来控制结构设计是偏于安全的。     

基于欧标的密肋型波纹钢筒仓结构设计

波纹钢筒仓的分析可将仓壁作为均匀壁厚的等效正交异性壳进行,对两向拉伸刚度和弯曲刚度进行修正,可高效建立波纹仓壁的等效有限元模型.基于欧洲规范[1-7],对意大利热那亚一直径16.38m、高度21.216m的实际波纹钢筒仓工程进行了结构设计分析.仓壁竖向加劲肋为开口薄壁型截面,共54根,周向距离为0.953m.考虑了永久荷载、屋面可变荷载、散料压力、风荷载及仓顶栈桥荷载,同时考虑了10种组合荷载工况的承载能力极限状态和正常使用极限状态.设计分析采用了大型商业有限元软件ANSYS.线性静力分析表明结构的强度及变形满足欧标的要求.强度设计由包含散料压力的工况9控制,最大Mises等效应力发生在仓壁中下区域且略小于材料的强度设计值fy.稳定性分析同时考虑了几何非线性和材料非线性,结果表明各工况下的稳定安全系数均大于欧标规定值1.1.满仓时结构的稳定性设计由工况9控制,而空仓时由工况2控制.抗风梁对提高仓壁在风荷载下的屈曲强度有很大的有益作用.     

某筒仓钢锥漏斗质量事故的分析处理

1.概述 某面粉厂钢板筒仓共八只,用于装小麦。每只筒仓直径为10m,筒高为21m。筒仓下设钢板锥形漏斗,漏斗上口直径为7.4m,用螺栓、法兰盘与钢筋砼环梁连接。筒仓剖面示意见图1。     

圆筒仓仓底折板深梁漏斗壁的设计简介

大直径筒仓仓底结构需要根据仓下工艺条件不同,而采用不同的仓下支承结构和仓底漏斗.大直径筒仓为防止卸料口起拱,工艺一般布置多卸料漏斗方案,如布置双排共4个或6个卸料漏斗,30m以上的筒仓甚至要布置4排卸料漏斗.两排卸料漏斗口下的给料机相向地将物料给到仓下同一条胶带输送机上.以往的设计方案是漏斗斜壁将荷载传给承重大梁,承重大梁再传给仓下支承结构(筒壁或框架柱).本文介绍一种漏斗斜壁和承重梁合二为一的结构形式--折板深梁漏斗壁.     

内压与局部轴压共同作用下钢筒仓屈曲性能研究(Ⅰ):参数分析

采用有限元方法研究了内压与局部轴压共同作用下钢筒仓的屈曲性能。研究的参数包括内压、局部轴压分布角及钢筒仓径厚比等。考察了各参数对筒仓屈曲模态、屈曲时对应的仓底反力、加载边中点下方仓壁的径向位移和环向应力等的影响。局部荷载作用下,仓壁的屈曲变形集中在仓壁局部。仓壁内将形成压力拱承受该局部轴压,且仓底局部范围内的反力为拉力。内压减小仓壁的屈曲变形。同时由于局部轴压作用下沿筒仓高度方向上仓壁的变形呈波浪状,仓壁内的环向应力沿高度方向相应呈波浪状变化。     

大型钢筒仓的结构行为与设计

筒仓结构广泛应用于农业、矿业、化工、电力等诸多领域中的散料储存.混凝土筒仓在国内已有许多应用,但钢筒仓的应用还很有限.过去二十年里国际上对钢筒仓结构的性能及强度进行了大量的研究,香港理工大学在近几年也进行了许多研究.本文总结了大型圆形钢筒仓结构行为及设计方面的近期研究进展.首先对钢筒仓的结构形式及散料荷载进行简单讨论,并介绍钢筒仓的主要破坏形式及相应的研究,给出了可供钢筒仓结构设计直接应用的部分主要设计公式.还介绍了钢筒仓结构设计中的计算机分析方法,最后指出钢筒仓结构尚需进一步研究的课题.     

氧化铝筒仓施工关键技术

钢筋混凝土筒仓工程施工中筒体工程、仓底及内部结构中漏斗施工是钢筋混凝土筒仓工程施工的重点、难点,本文通过我单位施工的某氧化铝输送及供配料工程中氧化铝群仓施工实例探讨氧化铝筒仓施工关键技术,筒体工程采用平台梁板、漏斗处局部空滑、留洞后支的施工工艺,在保证漏斗下部梁板承载力的前提下,以漏斗下部梁板为上部架体支撑面,确保了漏斗支撑体系的刚度、强度和稳定性,工程竣工后经检验,筒仓的结构实体检验、垂直度等均符合规范及设计要求,漏斗中心控制点、底部控制线及设计斜度偏差小于《钢筋混凝土筒仓施工与质量验收规范》GB 50669-2011的允许偏差,观感质量好,取得了高效、经济的效果,达到了预期的目标,对同类工程施工有一定的指导、借鉴意义。     

某试验型钢筒仓受力性能及案例分析

钢筒仓作为一种封闭存储大宗散料的方式,具有自重小、可充分发挥钢材的受拉性能、施工方便、外形美观等特点,愈发受到人们的青睐,通过查阅贮料相关物理参数,计算筒仓模型的结构受力情况,分析筒仓仓体面外荷载、加劲肋和筒仓墙体应力云图,验证了筒仓根部与下部支撑结构的锚固连接为工程设计的重点环节。     

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.     

Techniques for buckling experiments on steel silo transition junctions

Large elevated steel silos generally consist of a cylindrical vessel, a conical discharge hopper and a skirt which may either be supported on the ground or by a number of columns. The cone–cylinder–skirt junction is subject to a large circumferential compressive force due to the radial component of the meridional tension in the hopper, so either a ring is provided or the shell walls are locally thickened to strengthen the junction. Many theoretical studies have examined the buckling and collapse strengths of these junctions, but no previous experimental study has been reported. This has been due to the great difficulties associated with testing these thin-shell junctions at model scale. This paper first describes the development of an experimental facility for testing model steel silo transition junctions. Issues covered include the fabrication of quality model junctions using thin steel sheets, the loading method and the precise three-dimensional measurement of geometric imperfections and deformed shapes using a laser-displacement meter. Typical experimental results of a cone–cylinder–skirt–ring junction are next presented to demonstrate the capability of the developed facility. Procedures for processing the test results to determine both the buckling load and the number of buckling waves are also presented.     

Buckling experiments on steel silo transition junctions: II: Finite element modeling

This paper is concerned with the finite element modeling of the experiments on cone–cylinder–skirt–ring transition junctions in steel silos under simulated bulk solid loading presented in the companion paper. Before presenting the finite element results, the issue of modeling the interaction between the stored solid and the shell wall throughout the loading process is first examined. Results from nonlinear bifurcation analyses using the perfect shapes and nonlinear analyses using the measured imperfect shapes are then presented and compared with the experimental results. These comparisons show that despite the structural complexity of steel silo transition junctions, their behavior can be satisfactorily predicted by finite element analyses taking into account a number of important factors including geometric imperfections, effects of welding and the interaction between the junction and the stored solid. Next, the paper presents results of nonlinear analyses of these junctions with assumed eigenmode-affine imperfections. These results shed considerable light on the effect of ring buckling on the load-carrying capacity of transition junctions. Finally, the implications of the experimental and finite element results for the design of steel silo transition junctions are discussed.     

Out-of-plane strength design of spatially trussed arches with a rectangular lattice section

Although several studies of the out-of-plane strength and design of steel arches with a solid web section have been reported, little research of the out-of-plane strength and design of spatially trussed arches has been reported in the open literature or design codes. In deference to the steel arch with a solid web section, the shear deformations play important parts in the out-of-plane inelastic buckling behavior of spatially trussed arches. In addition, global out-of-plane inelastic buckling of a spatially trussed arch is associated with local buckling of its components such as chord and diagonal web tubes and hence local component buckling influences the out-of-plane strength of the arch. This paper investigates the out-of-plane inelastic strength and design of spatially trussed circular arches with a rectangular lattice section under general loading using a three-dimensional nonlinear inelastic numerical approach. Methods for the out-of-plane inelastic strength and design of spatially trussed arches under uniform compression or under uniform bending are developed, based on which interaction equations for the design of spatially trussed steel arches under general loading against their out-plane failure are proposed. These interaction equations provide good lower bounds for the out-of-plane strength of spatially trussed arches.     

考虑屈曲效应的混凝土柱纵筋低周疲劳性能和变形能力研究

屈曲导致的局部塑性应变集中将使钢筋损伤加重,并提前断裂。传统低周疲劳损伤模型(如Coffin-Manson模型,简称C-M模型)中未考虑屈曲效应的影响,这将高估屈曲钢筋的低周疲劳寿命。为研究屈曲对钢筋疲劳寿命的影响,完成了30个原状钢筋试件考虑屈曲的循环加载试验,得到了钢筋断裂时的极限塑性平均应变的测量结果,分析了局部应变与试件平均应变的差别。建立有限元模型,对屈曲钢筋循环加载试验进行模拟,验证了模型的可靠性,并提取了屈曲钢筋关键截面的局部应变,将塑性平均应变幅、塑性局部应变幅分别代入传统C-M模型,得到了累积疲劳损伤指数计算结果,并与试验结果进行了对比分析。建立了可合理考虑钢筋屈曲效应影响的改进低周疲劳损伤模型,可更准确地计算屈曲钢筋循环受力试验的疲劳寿命。研究结果表明：基于塑性局部应变幅的传统C-M模型高估了屈曲钢筋的低周疲劳损伤,基于塑性平均应变幅的传统C-M模型低估了屈曲钢筋的低周疲劳损伤;基于塑性局部应变幅平均值的改进C-M模型精度更高,但测量、计算局部应变困难;基于塑性平均应变幅的改进疲劳损伤模型精度相对稍低,但使用方便。改进低周疲劳损伤模型可有效考虑屈曲对钢筋低周疲劳寿命的影响,能更准确地预测钢筋混凝土柱纵筋的屈曲断裂时刻。     

Post-buckling of a non-uniform ring subjected to uniform external pressure

Rigid plastic analysis is used to find the post-buckling response of a non-uniform circular ring subjected to uniform external pressure. The non-uniform ring has a section of reduced thickness over part of its circumference. A five plastic hinge model is used to describe the non-axisymmetric post-buckling collapse. The principle of virtual work and upper bound theorem are applied to find the collapse pressure and mode of collapse. Depending on the non-uniformity, two modes of collapse can occur: global and snap-through buckling. Global buckling occurs when the angular extent is greater than 90 degrees. When the angular extent is less than 90 degrees and the thickness reduction is large, snap-through buckling takes place. Closed-form expressions for the variation of the collapse load with respect to non-uniformity of the ring are derived.     

Rubber effect on metallic dampers used on the supports of steel cross members

There are many strengthening methods made with steel cross members for strengthening the structures with inadequate earthquake behavior. This type of strengthening methods is also effective in buckling of the cross members in the behavior of the structural frames. This buckling may cause partial or complete collapse of the structure. Thus, it is quite important to prevent and limit the formation of buckling in steel crosses. At the TEC 2018, the insulation unit is defined as the elements that can exhibit flexible behavior on the horizontal direction and rigid behavior on the vertical direction under the effect of earthquake loads. The basic principle of using insulation units is that these members can dissipate energy in the carrier system. The originality of this study is to experimentally investigate the damper behavior created by using cylindrical rubber wedges, which can be easily found in the automotive industry, in combination with steel plates and bolts. In this experimental study, the contribution of seismic insulators to the structural element to be strengthened was investigated. The insulators used in this study are considered by analogy with lead-core rubber insulators. As such seismic lead-core rubber insulators move under the influence of lateral loads, the lead core inside makes plastic deformation, thus increasing the damping rate. In this insulator study, it is aimed to use U plates or bolts instead of lead core. While vertical loads are covered by rubber support, horizontal loads will be damped due to plastic deformation of U plates or bolts. The five types of seismic dampers were used as 10 B-type rubber wedge mounted damper (SR), 2 U-type steel plates damper (SP), 10 M6 steel bolted damper (SB), 2 U-type steel plates and 10 B-type rubber wedge mounted damper (SPR), 10 M6 steel bolted, and 10 C-type rubber wedge mounted damper (SBR). These specimens were tested under lateral loading and constant vertical loading. The results obtained at the end of the tests shall be compared considering the strength, stiffness, and dissipated energy capacities of the specimens.     

圆弧钢拱破坏荷载的理论计算

拱结构经常在桥梁、屋顶等大跨结构中使用。尽管这些结构构件容易出现各种失稳现象,但其中短粗拱或细长拱的侧向水平连接失效是由塑性破坏而非平面内或平面外屈曲引起的。通过极限荷载方法分析塑性破坏荷载,以最大限度地发挥截面的塑性能力和出现塑性铰后的内力重分布能力。描述了竖向荷载下圆弧钢拱塑性破坏荷载的计算方法。使用塑性力学中的上限法、下限法和位移协调法来计算塑性破坏荷载,压力致使拱截面的容许塑性力矩减小。确定外荷载与容许塑性力矩之间的非线性关系后,使用迭代法得到塑性破坏荷载。利用有限元方法对分析结果进行检验,二者的分析结果相吻合。最后基于迭代法绘制设计图。     

高含钢率SRC柱轴压承载性能研究

通过对3根含钢率为24.3%的SRC柱的轴压试验,对高含钢率SRC柱构件的轴压承载性能进行了研究。分析了试件的荷载-位移关系曲线特征,揭示了高含钢率SRC柱以钢骨为主要受力部分,依次发生混凝土开裂和压溃、钢筋屈曲、钢骨弯曲失稳等破坏形态。利用有限元软件ABAQUS对试验过程进行了模拟。研究表明,高含钢率SRC柱具有钢构件的承载特性,钢骨塑性阶段的整体失稳导致极限后的承载力下降;工程设计可以采用塑性准则和叠加原理计算其极限承载力。