共查询到19条相似文献,搜索用时 196 毫秒
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为研究薄壁槽钢整体屈曲下的数值算法的适用性,以4种不同杆端约束下的薄壁槽形截面压杆为研究对象,根据广义梁理论确定其发生弹性整体屈曲的有效长度及临界荷载,与开口薄壁理想压杆的线性及非线性解析解进行对比,得到一致的临界荷载。利用ABAQUS有限元分析软件建立壳体有限元模型,采用杆端截面形心集中加载,依据约束情况确定杆端约束,以及根据有效长度施加不同初始缺陷的计算模型,开展特征值算法和隐式弧长法数值计算分析。计算结果表明:当开口薄壁压杆的有效长度足够大时,临界荷载的特征值数值解与理论解一致,弧长法计算得到的非线性解误差相对较大。当有效长度不够大时,弧长法计算得到的极限荷载与理论解基本一致,且弧长法可有效追踪后屈曲路径。 相似文献
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单轴对称开口薄壁压弯构件在荷载作用于对称平面内时有可能发生弯扭屈曲。在这种情况下,其临界荷载总是低于平面内弯曲失稳破坏荷载,如果在构件的开口边加上缀板,使之形成若干断续的封闭截面,则弯扭屈曲临界荷载将显著提高,并有可能使破坏模式由弯扭屈曲转化为平面内弯曲失稳。本文提出了一种计算薄壁压弯构件弯扭屈曲荷载的方法,这种方法对局部封闭和开口截面都能适用。曾经做了213根具有不同长细比、偏心距、缀板间距(或无缀板)的冷弯薄壁型钢压杆试验,其结果与理论符合较好。 相似文献
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研究了截面形心和剪切中心重合的多弹性扭转支承开口薄壁杆在轴向压力作用下的扭转屈曲,把作用在开口薄壁杆上的弹性扭转支承去掉,代之以相应的未知扭矩,采用Laplace变换推导出了其扭转变形的位移函数,并求得了多弹性扭转支承开口薄壁杆在轴向压力作用下扭转的屈曲特征方程。 相似文献
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对冷弯开口薄壁帽型截面受压构件的压弯极限承载力进行了分析研究,主要考虑构件长细比、荷载偏心距和构件初弯曲对压弯极限承载力的影响。利用MATLAB7.0.1和ANSYS10.0计算得到受压构件基于截面边缘纤维屈服准则的临界荷载和弹性弯扭屈曲荷载,进而利用ANSYS10.0对受压构件的弹塑性极限荷载进行了计算。通过对三种不同的计算方法得到的极限荷载进行比较,分析了冷弯开口薄壁帽型截面受压构件压弯极限承载力的计算方法。结论中评价了单轴对称截面压弯构件的设计公式。研究表明,该设计公式具有一定的安全储备,满足设计要求。 相似文献
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针对薄壁杆件力学分析较为复杂的问题,讨论了一种把开口薄壁杆的分析拆分为2个较简单部分的方法。针对薄壁中面内荷载效应的分析问题,首先在适当简化基本应力应变条件的基础上,按平面应力问题分析单肢板件面内荷载效应,然后对其进行向量综合,得到反映开口薄壁杆轴向伸缩、弯曲及翘曲性质的“板件面内拉弯综合抗力体系”及其变形方程;探讨了刚度方程的建立及其计算特点,并与经典理论进行对比。分析表明,在板件面内弯矩定义中引入板件间纵向相互作用力,可简化该体系分析过程和结论,使之具备与平面弯曲问题一致的形式。作为应用举例,推导了求解薄壁截面主轴方向、主轴惯性矩、弯心坐标、主扇性惯性矩的线性方程组,剖析了经典理论中这些截面几何特性对于计算的意义及其效率。 相似文献
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本文将变截面圆形薄壁压杆的基本微分方程变换为贝塞尔方程,将其解用初等函数表达出来,并使得临界荷载的计算公式不仅形式上简单而且计算简便,利于在工程设计中直接采用。 相似文献
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开口截面的冷弯薄壁钢梁在工业建筑中被广泛应用。这类梁截面的形状使得它们很容易产生局部屈曲。归纳了对卷边工字型梁进行试验的研究结果。梁上作用荷载有弯矩和集中力。此外,还将试验中获得的临界荷载数值与有限元分析和其他理论分析中得到的数据进行了对比。 相似文献
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<正>在计算开口薄壁偏心压杆的弯扭屈曲临界力时,过去都是假定弯矩沿杆长无变化,即忽略屈曲前变形所引起的附加弯矩影响。根据这一假定可以列出常系数微分方程组,求解比较容易,但不可避免地会给计算结果带来某 相似文献
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《Thin》2014
Results of a theoretical analysis of the local buckling in thin-walled bars with open cross-section subjected to warping torsion are presented. The local critical bimoment, which generates local buckling of a thin-walled bar and constitutes the limit of the applicability of the classical Vlasov theory, is defined. A method of determining local critical bimoment on the basis of critical warping stress is developed. It is shown that there are two different local critical bimoments with regard to absolute value for bars with an unsymmetrical cross-section depending on the sense of torsion load (sign of bimoment). However, for bars with bisymmetrical and monosymmetrical sections, the determined absolute values of local critical bimoments are equal to each other, irrespective of the sense of torsional load. Critical warping stresses, local critical bimoments and local buckling modes for selected cases of thin-walled bars with open cross-section are determined. 相似文献
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An arch with an open thin-walled section that is subjected to a radial load uniformly distributed around the arch axis may suddenly buckle out of its plane of loading and fail in a flexural-torsional buckling mode. The classical flexural-torsional buckling load for an arch with an open thin-walled section under a uniform radial load has been obtained by a number of researchers, based on the consideration that the uniform radial load produces a uniform axial compressive force without in-plane bending prior to the occurrence of flexural-torsional buckling. This assumption is correct for deep arches. However, the uniform radial load may produce substantial bending actions in shallow arches prior to flexural-torsional buckling, and so the classical buckling analysis based on the assumption of uniform axial compression may produce incorrect flexural-torsional buckling loads for shallow arches. This paper investigates the flexural-torsional buckling of shallow arches with an open thin-walled section that are subjected to a radial load uniformly distributed around the arch axis. It is found that shallow arches under a uniform radial load are subjected to combined in-plane compressive and bending actions prior to flexural-torsional buckling, and that using the classical buckling solution for circular arches under uniform compression produces incorrect buckling loads for shallow arches. A rational finite element model is developed for the flexural-torsional buckling and postbuckling analysis of shallow arches with an open thin-walled section, which allows the buckling loads to be obtained correctly. 相似文献
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Tripping of stiffeners in stiffened panels under combined loads of axial force and lateral pressure is studied. Firstly, on the basis of the Vlasov's differential equation for torsional buckling of thin-walled bars, a generalized eigenvalue problem for tripping of stiffeners is derived by using the Galerkin's Method. Then the effect of the lateral pressure (dead load) to the critical axial stress (live load) upon tripping is investigated by solving the eigenvalue problem. The rotational restraint provided by the plate is taken into account. The effects of the compressive stress in the plate and the plate buckling mode are also discussed. Finally, an approximate equation to estimate the critical tripping stress with the effect of the lateral pressure is proposed. After some modifications, it can be applied in design rules for the purpose of checking the tripping strength of the stiffeners. 相似文献
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A more rational and accurate analysis is presented for the torsion of braced thin-walled open section bars with transverse connections. The approach is based on Vlasov's thin-wall beam theory in conjunction with the continuous medium method. Shearing deformations in the middle surface of the thin wall are also taken into account. The analysis gives a generalized sectorial coordinate to estimate the realistic torsional stiffness of the thin-walled member, and provides a better physical interpretation of the relationship between the sectorial properties and the applied torque. 相似文献
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A consistent theory for torsion of thin-walled bars with cross-sections of arbitrary shape (open, closed or mixed) is developed in this paper; it is an improvement on the classical torsion theory of thin-walled bars. All the basic relations, formulas and equations are derived and proved under the consistent assumptions. A torsional stiffness matrix for thin-walled bar elements is also formulated on the basis of the consistent theory. A computer program has been written which is applicable to the practical use of torsional analysis of thin-walled bar structures with arbitrary cross-sections. 相似文献
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为了解约束拉杆预拉力对矩形钢管混凝土短柱受力性能的影响,进行了3个带预应力约束拉杆短柱轴压试验和另外2个对比试验,对比试验试件中1个不带约束拉杆,1个带普通约束拉杆。预应力约束拉杆和普通约束拉杆均由M20高强度螺栓组成,作为普通约束拉杆的高强度螺栓,在构件受轴向压力前与钢管壁焊接成一体;作为预应力约束拉杆的高强度螺栓,在构件受轴向压力前通过扭紧螺帽产生预拉力,然后与钢管壁焊接成一体,由拉杆预拉力对钢管壁和核心混凝土进行预压。试验结果表明,设置约束拉杆后,构件的承载力提高,轴向变形能力增强;与普通约束拉杆相比,预应力约束拉杆能减小构件最大荷载时的变形,但对构件承载能力和后期变形能力影响不大;减小预应力约束拉杆的横向间距,可有效减小构件最大荷载时的轴向变形,提高构件前期刚度,但对构件承载力影响不明显;在截面宽度和拉杆数量不变的情况下,随着截面长宽比的增加,构件后期变形能力减小。 相似文献
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The problem of local stability loss in the elasto-plastic range of a thin-walled column, loaded by uniform compressive stresses, is examined on the basis of the J2 deformation theory and the J2 incremental theory of plasticity. The problem is solved in two different ways. Several types of closed and open cross-sections are considered. The results of numerical calculations are presented in graphical form, showing the relationship between the critical stress and the slenderness ratio for the column section. All possible buckling modes in the elastic range and local buckling in the elasto-plastic range are demonstrated in the case of a column of channel form cross-section. 相似文献
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The paper deals with dynamic buckling of thin-walled structures (plates and beam-columns with open cross-section) subjected to compressive rectangular pulse loading. The local, global and interactive dynamic buckling was analysed. Author proposes the new criterion for critical amplitude of pulse loading leading to stability loss. The proposed criterion is a modification of quasi-bifurcation criterion formulated by Kleiber, Kotula and Saran. Results obtained using proposed criterion were compared with other well-known criteria (Volmir (V) and Budiansky–Hutchinson (B–H) criterion). 相似文献
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An innovative X section with intermediate stiffeners of thin-walled concrete-filled steel stub was proposed in this study. The X section was firstly brake-pressed from structural steel sheets to form three edges open section with intermediate stiffener in each edge, then a plate with intermediate stiffener was welded to the open section to form the closed section. The intermediate stiffener was designed to enhance the local buckling stress of the thin-walled specimens. Stub column tests of both hollow steel tubes and concrete-filled steel tubes were performed. Material properties of the self-compacting concrete and steel used in the test specimens were also measured. Design methods specified in current design standard and proposed by other researchers are used to predict the design strengths of test specimens. It is shown that the predicted design strengths are conservative. 相似文献