冷弯开口薄壁帽型截面受压钢构件压弯承载力的研究

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。     

平面内弯曲变形对构件弯扭屈曲的影响

基于更精确的平衡微分方程式,导出了弯曲平面内变形对受弯和压弯构件弯扭屈曲临界荷载的影响的修正因子．该因子形式简单,且由于它考虑因素全面,使修正后的公式应用广泛．在经典解中计入修正因子就得出准确的临界荷载。对于受弯构件,修正后其临界弯矩的提高只与构件截面的ＥＩｘ和ＥＩｙ有关;对于压弯构件,修正后其临界荷载的变化还与因子（１—Ｎ／ＮＥ）的平方有关。     

薄壁型钢偏心受压构件的稳定计算

薄壁型钢偏心受压构件,在外加荷载作用下,可能以下述四种形式丧失稳定:1.纯粹的压屈;2.在偏心力矩作用平面内弯曲失稳;3.在偏心力矩作用平面的垂直方向弯曲失稳(通常这种弯曲总伴随有扭转发生,故常称为弯扭失稳。开口薄壁型钢由于其开口的外形、较薄的外壁、抗扭刚度较     

钢压弯构件弯扭屈曲的研究

本文简要介绍了近年来在西安冶金建筑学院完成的有关钢压弯构件弯扭屈曲研究的成果,包括以下几个方面;(1)确定钢压弯构件设计承载力的典型截面选择;(2)考虑钢材屈服非连续性或焊接残余应力影响时构件的非弹性弯扭屈曲;(3)单轴对称截面压弯构件的弯扭屈曲分析和试验研究;(4)双轴和单轴对称截面构件弯扭屈曲的实用相关公式;(5)绕截面弱轴弯曲的压弯构件的弯扭屈曲分析和试验;(6)冷弯薄壁型钢构件的非弹性弯扭屈曲的分析和试验。     

腹板开孔冷弯卷边槽钢受弯构件弹性屈曲

采用理论和有限元方法分析腹板开孔冷弯薄壁型钢受弯构件弹性整体弯扭失稳、弹性畸变屈曲失稳以及弹性局部屈曲失稳的屈曲荷载。通过理论分析提出计算腹板开孔卷边槽形截面受弯构件弹性整体弯扭失稳、弹性畸变屈曲失稳以及弹性局部屈曲失稳荷载的简化计算方法,通过与有限元计算结果进行对比,近似简化方法计算结果与有限元分析结果比较接近,表明建议弹性屈曲荷载计算方法具有较高的精度,可用于开孔受弯构件整体稳定承载力以及屈曲稳定系数的计算,能够代替复杂的有限元方法进行开孔构件弹性屈曲荷载的简化计算,易用于工程设计。     

轴心受压开口薄壁构件弹塑性屈曲荷载的统一计算方法

通过分析构件截面上应变与轴向力间的关系，以构件轴向应变为基本参数，提出了轴心受压开口薄壁构件的弹塑性屈曲荷载统一计算方法，给出了轴压构件的弯曲屈曲、扭转屈曲、弯扭屈曲等屈曲荷载的弦截法迭代格式，可应用于H形、T形、L形、十形截面等不同开口形式的轴压构件屈曲荷载计算，并可考虑具有残余应力的弹塑性本构关系。该方法以无残余应力的弹性屈曲荷载对应的轴向应变作为初始值，根据不同屈曲形式对应的非线性方程计算弦截区间点的函数值，进行弦截法迭代计算，得到弹塑性构件的临界轴向应变，进而获得屈曲荷载等信息。该方法采用的弦截法收敛速度快、计算量小、无需嵌套循环，可有效解决两端铰接轴心受压开口薄壁构件的弹塑性屈曲快速计算问题，便于工程应用。     

冷弯薄壁型钢卷边槽形截面构件畸变屈曲控制研究

基于部分加劲板件的畸变屈曲和局部屈曲的稳定系数比较,提出了冷弯薄壁型钢卷边槽形截面构件畸变屈曲发生于局部屈曲之后或畸变屈曲不发生的临界控制条件;给出了通过构件畸变屈曲计算长度控制畸变屈曲的临界条件;提出一种控制畸变屈曲的构造措施,即在卷边间加设缀板,并通过已有试验对其有效性进行验证,同时推导了卷边间缀板的刚度需求。结果表明：通过构件截面尺寸控制畸变屈曲不发生或发生在局部屈曲之后,可以不考虑构件畸变屈曲的影响,简化冷弯薄壁型钢卷边槽形截面构件承载力的计算;计算长度小于畸变屈曲半波长一半的构件不发生畸变屈曲;通过在卷边间加设缀板的构造措施能有效阻止部分加劲板件的转动,构件的畸变屈曲荷载和承载力都有很大的提高,缀板布置间距不同,构件承载力的提高幅度也不同,缀板间距越小,构件承载力提高幅度越大。算例分析表明,满足一定间距和刚度需求的缀板能够提高构件的畸变屈曲承载力或避免畸变屈曲的发生。     

基于ECBL理论的冷弯薄壁型钢柱相关屈曲研究

为研究冷弯薄壁型钢柱的相关屈曲,介绍了一种分析柱构件相关屈曲的方法——临界分叉荷载侵蚀理论(ECBL理论)。该方法考虑了试件在截面屈曲(局部屈曲或畸变屈曲)和整体屈曲(弯曲屈曲、扭转屈曲或弯扭屈曲)相互作用下的稳定极限承载力,通过评估、量化构件的侵蚀因子和缺陷因子使Ayrton-Perry方程表示的屈曲曲线适用于冷弯薄壁型钢构件的相关屈曲分析。利用此理论对我国既有的部分冷弯薄壁型钢柱试验数据和有限元分析结果进行了处理,提出了对应的相关屈曲曲线。     

单轴对称工字形截面圆弧拱的屈曲分析

根据文献[1]提出的任意开口薄壁截面圆弧曲梁的翘曲位移表达式,本文利用能量原理导出了单轴对称工字形截面拱的稳定平衡方程。文中主要对工字形截面拱在均布径向荷载 (均匀受压 )和两端作用大小相等、方向相反的端弯矩 (均匀弯曲 )条件下的弯扭屈曲进行分析,给出临界荷载的理论解答;考虑了工字形截面不同放置时拱失稳模式的不同,分析截面不对称性对临界荷载的影响,并与已有的文献进行比较。     

双轴对称楔形工字钢梁的弹性弯扭屈曲

本文利用基于板壳屈曲理论的有限元方法对楔形薄壁构件的弯扭屈曲进行了分析,对两种基于薄壁杆件理论的楔形工字钢梁弯扭屈曲分析方法进行了对比。基于较精确的楔形薄壁构件屈曲理论,对承受线性变化端弯矩作用的楔形梁的弯扭屈曲进行了大量分析,并提出了新的楔形工字钢梁临界弯矩计算公式。该公式形式与等截面梁的相同,便于工程应用。     

Torsional-flexural buckling of open thin-walled columns with battens

A rational method for determining the torsional-flexural buckling load of thin-walled open sections with battens is presented. Theoretical results are compared with experimentally obtained buckling loads for a number of different cases. It is shown that torsional-flexural buckling behaviour is dependent on the number and spacing of the battens used and the torsional-flexural buckling load can be predicted with reasonable accuracy using a simple formula which is valid for both battened and unbattened columns.     

钢异形柱弯扭相关屈曲研究

用弹性薄壁柱理论,推导了开口任意截面柱弯扭屈曲相关方程,并由此简化到单轴对称截面、双轴对称截面经典方程。进而研究了L形柱轴向受压的承载力即φ-λ曲线,以便工程设计应用。     

Euler buckling of thin-walled composite columns

Pultruded composite structural members with open or closed thin-walled sections are being extensively used as columns for structural applications where buckling is the main consideration in the design. In this paper, global buckling is investigated and critical loads are experimentally determined for various fiber reinforced composite I-beams of long column length. Southwell's method is used to determine the critical buckling load about strong and weak axes. The experimentally determined buckling load is compared with theoretical predictions. A number of observations about testing methodology and data reduction techniques are presented.     

Ultimate capacity of battened columns composed of four equal slender angles

Cold-formed steel structural members play a great role in modern steel structures due to their high strength and light weight. The behavior and strength of battened column members composed of slender angle sections are mainly governed by local buckling of angle legs or torsional buckling of the angle between batten plates. Moreover, local buckling depends on the interaction between the width–thickness ratio of angle leg, overall slenderness ratio of angle between batten plates and overall slenderness of column. Theoretical study has been carried out by a nonlinear material and geometrical finite element model. Numerous cases of slender battened column sections having different width–thickness angle leg ratios, overall slenderness ratios between batten plates and overall slenderness ratios are chosen in this study. Complete ultimate strength curves are drawn and different failure modes are studied by taking different member lengths, which produce local or torsional buckling of single angles between batten plates or overall buckling of the member. Empirical equations for the effect of shear deformation factor and the ultimate axial load capacities of members formed of battened slender angle sections are proposed. Strengths of axially loaded battened members predicted using finite element as well as the proposed empirical equations is compared with the design strengths obtained using North American and European codes. It is concluded that the design strengths predicted by North American and European codes are generally conservative, and these design rules have been shown to be reliable using reliability analysis.     

高强冷弯薄壁型钢卷边槽形截面轴压构件畸变屈曲控制试验研究

针对屈服强度550MPa高强冷弯薄壁型钢轴压构件提出了一种控制畸变屈曲的构造措施--在卷边间设缀板,并通过试验对其有效性进行了验证。试验结果表明：屈服强度550MPa高强冷弯薄壁型钢卷边槽形截面轴压构件易发生畸变屈曲,通过构造措施能有效地阻止翼缘的转动,试件的畸变屈曲荷载和极限承载力都有很大的提高;随着缀板布置间距的不同,构件承载力的提高幅度也不同;缀板间距越小,试件承载力提高越多,但当缀板间距大于畸变屈曲半波长时,缀板不能起到提高承载力的作用。最后,在此基础上提出了构件不考虑畸变屈曲影响的若干条件,供实际设计参考。     

高强冷弯薄壁型钢卷边槽形截面偏压构件试验研究及承载力分析

进行了48根屈服强度550MPa高强冷弯薄壁型钢卷边槽形截面偏心受压构件试验,考虑了不同截面形式、厚度、长细比和荷载偏心方式的影响,研究了这类偏心受压构件的破坏模式、承载力影响因素以及构件承载力计算方法。结果表明：高强冷弯薄壁型钢偏压构件由于材料强度高,截面宽厚比较大,局部屈曲和畸变屈曲的影响较大,我国规范仅考虑了局部屈曲的影响而没有全面考虑畸变屈曲的影响,这使得部分发生畸变屈曲的试件计算结果偏于不安全,但又对不发生畸变屈曲的长细比较大的构件偏于保守。最后,在试验和现有规范方法比较分析的基础上,提出了一种适用于高强冷弯薄壁型钢偏压构件极限承载力的建议计算方法。该建议方法计算所得结果与试验结果吻合较好,且安全可靠,可供设计参考。     

Flexural-torsional buckling of shallow arches with open thin-walled section under uniform radial loads

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.     

Buckling analysis of thin-walled members with closed cross sections

In this paper, an analytical procedure for the elastic buckling problems of thin-walled members with closed cross sections by the transfer matrix method is presented. The transfer matrix is obtained from the differential equations for a plate subjected to axial load, and the extended transfer matrix for closed cross sections is derived from that for branched panels. The analytical local and overall elastic buckling loads for thin-walled members with closed cross sections can be obtained simultaneously. Furthermore, a technique to estimate the buckling mode shapes of these members is also shown. To investigate the accuracy and efficiency of this method, some numerical examples are presented.     

A more accurate evaluation of buckling loads of thin-walled members in torsion and torsion-bending

The objective of this paper is to present a more accurate evaluation of torsional and torsional-flexural buckling loads of thin-walled members. Numerical examples, which exhibit the accuracy of the formulae obtained in the buckling analysis of thin-walled members, are given.     

冷弯薄壁梁的屈曲及优化设计综述

介绍了冷弯薄壁梁的整体-局部屈曲和优化,包括:简化分析与计算、数值分析及试验。详细阐述了薄壁梁翼缘和腹板的屈曲问题。采用质量检测方法,对不同横截面薄壁梁进行比较。