考虑腹板屈曲的门式刚架极限承载力参数分析

运用ANSYS对门式刚架在考虑梁柱腹板皆屈曲后的极限承载力进行双重非线性分析,研究了水平荷载、腹板高厚比、翼缘宽厚比、斜梁坡度、高跨比等参数对刚架极限承载力的影响.研究表明:工程范围内,水平荷载对刚架极限承载力的影响较小,可以忽略不计;腹板高厚比在80～200范围内,翼缘宽厚比在7.7～15.4范围内,高跨比(高度变化)在1/18～5/36范围内变化时,对刚架极限承载力的影响较大;高跨比(跨度变化)在1/12～1/7范围内变化时,对刚架极限承载力的影响较小;斜梁坡度在1/24～1/8范围内,刚架极限承载力基本不受影响.     

高强铝合金加筋薄壁梁板元相互作用研究

本文进行了某典型高强铝合金加筋薄壁梁的弯剪承载特性研究。依据工程要求设计了三种缩尺试验模型:横向加筋薄壁梁、附加纵向止裂筋薄壁梁和腹板开口补强薄壁梁。静力加载试验表明:(1)试验件破坏均由受压翼缘的局部屈曲破坏导致,但是不同试验件的屈曲翼缘弯曲变形方向不同;(2)处于腹板受拉区的纵向止裂筋不影响结构承载特性;(3)特别地,试验发现跨中腹板开口补强引起了相邻梁段屈曲翼缘承载力显著提升,目前普遍认为横向加强筋隔开的板元之间无相互作用,因此可以认为这是一种新的板元承载力相互作用。进而,基于被试验验证的有限元模型进行了材料屈曲强度的参数化分析,并证实材料屈服强度越高,板元相互作用引起的屈曲翼缘的承载力变化幅度越大。     

薄腹板T型梁的稳定分析

通过薄腹板T梁的稳定性理论分析,推导出列车运营荷载作用下梁整体稳定极限承载力和腹板屈曲的极限承载力,并利用ANSYS对24m高强度混凝土T型梁进行了有限元分析。     

船舶圆弧过渡肘板节点的屈曲破坏研究

船体构件腹板在连接端部逐渐升高形成圆弧过渡肘板节点,较大的腹板尺寸导致其受弯时易出现屈曲破坏,从而影响船体结构的安全性。以典型圆弧过渡肘板连接的横梁-肋骨节点结构为研究对象,采用极限强度试验与非线性有限元模拟方法,研究肘板节点受弯时的破坏模式、极限载荷以及屈曲过程,讨论肘板臂长、圆弧半径、面板厚度对节点结构屈曲破坏的影响。结果显示:考虑初始缺陷的非线性有限元模拟结果与试验结果一致;根据肘板尺寸的不同,屈曲破坏的位置包括靠近肋骨的横梁腹板区域以及肘板与横梁过渡圆弧处的腹板区域;随着肘板臂长的增加,不同圆弧半径时节点的极限载荷均为先增大后趋于不变;随着圆弧半径的增加,肘板臂长较小的节点极限载荷缓慢上升,肘板臂长较大的节点极限载荷则近似呈线性增长趋势;面板厚度对极限载荷的影响较小,随着面板厚度的增加,极限载荷先缓慢增加后趋于不变。     

大跨径斜拉桥钢锚梁式索塔锚固结构承载力分析

以鸭绿江界河公路大桥为工程背景,考虑了几何非线性、材料非线性和接触非线性影响,采用有限元方法,对钢锚梁结构的破坏形态和极限承载力进行分析。结果表明,钢锚梁式索塔锚固结构的破坏形式为钢锚梁受拉弯强度破坏,破坏荷载为设计荷载的5.8倍,结构有较大的安全储备。提出了钢锚梁腹板、拉索支撑结构以及钢牛腿的简化计算模型,结果表明理论计算结果与有限元计算结果较为吻合,能较好的预测钢锚梁的应力值和应力分布。     

腹板开孔的H型梁在压弯载荷下的失效行为和强度试验研究

腹板开孔的H型钢梁在船舶,航空器和海洋平台结构作为受弯构件被广泛运用。已有众多文献报道过关于腹板开孔梁遭受腹板卷曲破坏的情况,但腹板开孔加强遭受面板屈曲的情况未有详尽调查。因此文中开展6组试件的试验研究来调查腹板开孔的H型梁的失效行为和极限承载力,结果显示开孔影响了试件屈曲波的长度和数量。该研究结果可用于几何尺寸相似的实际结构。     

开孔补强对受剪复合材料工字型梁腹板稳定性的影响研究

文章通过试验与数值仿真计算研究了开口与补强对复合材料工字型梁腹板稳定性的影响。含长圆形开口复合材料工字型梁腹板一端被固定在试验架上,另一自由端被施加竖向剪切载荷。运用有限元软件Nastran对两种不同类型的复合材料工字型梁腹板(带长圆形开口和带开口补强)进行仿真分析,利用线性屈曲计算得到屈曲荷载,通过非线性静力分析研究其后屈曲过程,并通过实验验证了数值模型和仿真计算结果。在非线性分析中对工字型梁载荷—挠度的响应进行了分析,并用"蔡吴失效准则"预测了工字型梁的首层破坏载荷。研究结果表明:工字型梁腹板的长圆形开口周边应力/应变集中现象显著,应变值为非开口区域的三倍以上;插层补强能有效地降低口边应力/应变集中程度,同时使其结构稳定性承载力提高88%,极限破坏载荷提高了46.3%。本研究可为指导含孔梁腹板结构优化设计及其在实际工程上的选型应用提供试前分析依据和参考思路。     

船体梁弯曲极限强度分析

针对船体梁极限强度计算问题,研究基于弯曲承载力的极限状态分析技术。分析总结船体梁极限强度分析方法及研究现状,阐述简化逐步破坏法(Smith逐步破坏法)的技术流程,探讨基于非线性有限元极限强度分析技术中各参数设置对计算结果的影响。在简化逐步破坏法计算结果的基础上,利用非线性有限元法评估基于单跨模型和舱段模型的船体梁极限强度,并探究上层建筑对极限承载力的影响。     

客滚船压筋板极限承载力数值计算及敏感性分析

针对新型客滚船上采用的槽型压筋板，利用非线性有限元软件ABAQUS中的risk算法对设置初始压制缺陷的槽型压筋板模型进行受压极限承载力计算。计算发现槽型压筋板中部与焊接扁钢的板边部分所受压屈曲极限承载力不同，因此将槽型压筋板分成2个部分进行研究。通过计算并利用MATLAB对数据回归分析后发现：对于槽型压筋板中间部分，随着槽型间距和压筋板长度的增加，线性屈曲压力减小，受压极限承载力减小，破坏时的最大挠度增加；随着厚度增加，线性屈曲压力和受压极限承载力增加较少，破坏时的最大挠度降低。针对槽型压筋板焊接扁钢的板边部分，缩短板边扁钢与旁边槽型的间距及提高焊接扁钢的腹板厚度均能提高压筋板板边的极限承载压力。设计中可通过在压筋板边焊接扁钢且增加扁钢尺寸或以焊接制造的方式增加槽型高度减小槽型间距，以提高压筋板的极限承载力。     

梁板式高桩码头极限承载力概率分布

极限承载力概率分布是结构可靠度计算要解决的主要问题之一。针对在役高桩码头结构安全评估问题,选择结构材料性能参数与几何尺寸参数为随机变量,基于非线性有限元数值模型,采用蒙特卡罗法建立典型梁板式高桩码头极限承载力概率分布模型及统计参数。研究了水平荷载作用下无损结构的极限承载力概率分布及损伤位置、损伤程度和损伤数量对高桩码头极限承载力概率分布及统计参数的影响。结果表明:水平荷载作用下无损结构的极限承载力概率分布为正态分布,损伤位置、损伤程度和损伤数量不影响结构极限承载力的概率分布。在水平荷载作用下计算损伤结构的可靠指标时,可以采用无损结构极限承载力概率分布及统计参数进行计算。     

Effect of pitting corrosion on local strength of hold frames of bulk carriers (2nd Report)—Lateral-distortional buckling and local face buckling

Pitting corrosion is typical corrosion observed on coated hold frames of bulk carriers which exclusively carry coal and iron ore. In order to secure the safety of these types of bulk carriers, it is important to understand the effect of pitting corrosion on local strength of hold frames.

In order to investigate this effect, a series of 4- and 3-point bend tests on structural models which consist of web, shell and face plates has been carried out. Artificial pitting was created on the web plate to simulate pitting. In the 4-point bend tests, two equal concentrated loads have been applied vertically at the one-third points of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, lateral-distortional buckling occurred before reaching the ultimate strength and local buckling of the face plate was observed after reaching the ultimate strength. The effect of web plate pitting on the lateral-distortional buckling strength was found to be small but the ultimate strength decreases with increase in the degree of pitting intensity. In the 3-point bend tests, concentrated load has been applied vertically at the center of simply supported models so that compression load due to bending would act on the face plate. In this testing condition, local face buckling occurred just after reaching the ultimate strength. The ultimate strength is found to be decreasing with increase in the degree of pitting intensity.

A series of non-linear FE analyses has been performed to simulate the deformation behavior observed in the tests. It has been revealed that even in the case of randomly distributed pitting corrosion the ultimate strength of the structural models was almost the same as that of the structural models with uniform corrosion corresponding to the average thickness loss.     

Laser-welded web-core sandwich plates under patch loading

This paper presents an approach to the structural analysis of patch-loaded, laser-welded web-core sandwich plates. This approach is especially suitable for the concept design phase of ship structures. The method consists of two parts; the global bending response is evaluated using sandwich plate theory and the local response of the patch-loaded face plate is determined with the help of basic plate theory. Both analyses utilise analytical and numerical methods and include the effect of the rotation stiffness of the laser-welded T-joint between the face and web plate. Combining the results of these two analyses gives the total response of the web-core sandwich plate. The results of the proposed approach are compared to those given by 3D solid and shell element FE analyses and the agreement of deflections and normal stresses is found to be good. The sensitivity of the response to patch-load size, T-joint rotation stiffness, and plate aspect ratio is studied. The main benefits of the proposed approach are its short analysis time and the good accuracy of deflections and stresses. This considered advantageous when applied to the design of large ship structures such as hoistable car decks.     

邮轮高腹板梁开孔应力分析

针对邮轮的甲板纵桁和横梁的腹板布置大量开孔,开孔削弱腹板截面尺寸,并且次弯距的影响显著,引起开孔边缘出现应力集中的问题,结合船级社规范开孔规则要求,采用有限元法分析开孔尺寸、开孔位置和补强方式对孔周切向正应力的影响,结果表明,孔周切向正应力对于开孔高度变化的敏感度大于开孔长度变化;当开孔的垂向位置越偏向面板时,孔周切向正应力增加趋势越明显;孔边缘加面板是最有效的减小应力集中的方式。     

A study of fatigue crack propagation at a web stiffener on a longitudinal stiffener

Predicting fatigue crack growth after its detection during in-service inspection is necessary to prevent a loss of serviceability, such as the oil and/or water tightness of critical compartments. This paper focuses on the most typical fatigue cracks that start at the weld joint between a flat bar stiffener on a transverse web frame and the flange of a longitudinal stiffener on a bottom plate or inner bottom plate. An experiment is carried out to observe the fatigue crack propagation for two kinds of flat bars at the abovementioned connection. The experimental results, especially the surface crack growth on the flange (which dominates during the total fatigue life of the longitudinal stiffener), are compared with crack growth curves predicted using a few existing formulas. Based on the comparative study, a formula that shows the best agreement with the experiment results is selected. Weld toe magnification factors for the web stiffener are computed from the crack propagation rates measured in the experiment, and two equations for the magnification factors versus crack depth are developed for two types of web stiffeners. The selected existing formula and the proposed equations are applied to two connections at the inner bottom and side longitudinal bulkhead of an LNG carrier. The equivalent stress approach based on a long-term distribution is employed to avoid the complexity involved in dealing with the actual stress history. Using this prediction, the remaining service life until an oil or water leakage occurs at a tank boundary can be estimated when a fatigue crack at the connection is detected.     

预应力混凝土曲线梁桥几个问题研究

曲线梁桥是弯扭耦合作用下的空间受力结构,现行桥梁规范所包括的内容滞后于桥梁的发展,平面分析的方法已不适用。文中对曲线梁桥的弯扭耦合效应、内外梁体受力不均以及恒载作用下结构产生较大的转矩等受力特点进行了分析。分析结果表明：曲线梁桥中间支承方式的设定不能改变支座的反力,外侧腹板弯矩内力均大于内侧腹板的弯矩内力,曲线半径越小,变化幅度越大。     

A general scaled model design method of stiffened plate subjected to combined longitudinal compression and lateral pressure considering the ultimate strength and collapse modes

A general and efficient scaled method for stiffened plates subjected to combined longitudinal compression and lateral pressure is proposed based on slenderness, simply by adjusting the number of stiffeners. The design method makes it easier to determine the dimensions of the scaled model for a given scale ratio compared with the previously proposed method. The emphasis is on the influence of the plate slenderness, the column slenderness, and the non-dimensional parameter of the lateral pressure on the ultimate strength. By maintaining the consistency of the plate slenderness and column slenderness, the proposed method is applicable for designing scaled models with materials of different yield stresses and Young's moduli. A similar effect of the lateral pressure on the ultimate strength of the prototype and scaled models is achieved by maintaining the non-dimensional parameter. In addition, the applicability of the scaled method to the initial deflection is considered, which provides a reference for similar models. The similitude of the scaled method is verified for several typical buckling modes, including the beam–column, tripping, web and overall collapse modes. Given the numerical results, the proposed general and fast scaled method can provide reasonable dimensions of scaled stiffened plates subjected to combined loads.     

开孔简支板格的剪切屈曲分析

目前CSR规范尚未对开孔较大的简支板格的剪切屈曲进行规定。针对这一点,采用结构非线性有限元数值分析方法,进行了一系列开孔简支板格的弹性剪切屈曲和塑性剪切屈曲的剪切极限承栽力计算分析,以尝试得出上述的屈曲能力,为规范的修订奠定基础。     

Ultimate torsional strength of flat-bar stiffeners attached to flat plating under axial compression

A parametric study based on numerical analysis using an efficient non-linear finite element method code is presented for the simulation of the interactive flexural-torsional failure behaviour of flat-bar stiffeners in plates under uniform axial compression. The restraining effect of the structural components on one another is investigated by varying the plate and stiffener slenderness. Initial imperfection levels partinent to marine structures have been accounted for. Strength curves for the allowable stress at the top of the stiffener due to elasto-plastic torsional buckling are given for use with approximate design formulas.