螺栓连接蜂窝梁孔间腹板屈曲性能分析

对螺栓连接蜂窝梁和传统焊接连接蜂窝梁孔间腹板屈曲性能进行了有限元分析,研究了不同连接方式对蜂窝梁孔间腹板的屈曲模式和屈曲承载力的影响。蜂窝梁上、下两部分的连接方式包括焊接、螺栓搭接连接、借助单侧拼接板对接和借助双侧拼接板对接等。结果表明,在相同截面尺寸、相同孔径的情况下,螺栓连接蜂窝梁具有与传统焊接蜂窝梁相同的受力性能;除借助单侧拼接板对接的蜂窝梁发生孔间腹板局部压屈与费氏剪力塑性铰耦合破坏外,其它连接方式的蜂窝梁均发生孔间腹板屈曲破坏;不同的连接方式对蜂窝梁的屈曲承载力影响较小,但对其跨中挠度影响较大。     

火灾下螺栓连接蜂窝梁孔间腹板屈曲性能分析

采用有限元方法研究了火灾下螺栓连接蜂窝梁的屈曲性能,并与传统焊接蜂窝梁进行了比较,分析了不同连接方式对蜂窝梁孔间腹板的屈曲模式和屈曲温度的影响。除焊接连接蜂窝梁外,还对上、下两T形部分采用螺栓搭接连接、借助单侧拼接板对接连接和借助双侧拼接板对接连接的蜂窝梁进行了研究。对焊接连接蜂窝梁和螺栓连接蜂窝梁,均假设腹板孔间温度均匀分布。分析结果表明:在相同截面尺寸情况下,螺栓连接蜂窝梁几乎具有与传统焊接蜂窝梁相同的抗火性能;借助单侧拼接板和借助双侧拼接板对接连接的蜂窝梁的屈曲温度略大于传统焊接蜂窝梁的屈曲温度;而采用螺栓搭接连接蜂窝梁孔间腹板的屈曲温度稍低于焊接连接蜂窝梁的屈曲温度。     

纯弯状态下蜂窝梁腹板的弹性屈曲分析

针对蜂窝梁腹板在纯弯状态下的弹性屈曲,利用ANSYS 15.0建立了正六边形孔蜂窝梁腹板在纯弯应力状态下的有限元模型,研究了四边简支开孔板在纯弯状态下的屈曲模式,分析了孔洞尺寸对蜂窝梁腹板屈曲临界应力的影响,提出了纯弯状态下开孔板的屈曲系数计算式,得到了蜂窝梁开孔腹板在纯弯状态下的高厚比限值。研究表明:无论开孔数目多少,最大平面外屈曲位移均发生在各孔洞正上边缘;蜂窝梁腹板高厚比是影响开孔板屈曲临界应力的主要因素,建议对于弯矩作用较大的蜂窝梁腹板取0.6γ0.7,0.7β0.8的孔洞尺寸容易实现稳定性和经济性要求(γ为孔高比,β为距高比);拟合出的开孔板屈曲系数计算式,误差不超过5%,具有良好的精度。     

蜂窝板及石材蜂窝板幕墙

蜂窝板是由两块表板和充填其中用以保证两块表板砌合在一起共同工作的蜂窝中间层所组成。表板可以选用不同的材料：当两块表板都是铝板或钢板时，称为铝蜂窝板或钢蜂窝板；当其中一块表板为石材、钛合金板、搪瓷板、木材、玻璃钢、塑料时，分别称为石材蜂窝板、钛合金蜂窝板、搪瓷蜂窝板、木材蜂窝板、玻璃钢蜂窝板、塑料蜂窝板等。中间蜂窝层采用铝箔、纸箔和塑料时，分别称之为铝蜂窝、纸蜂窝、塑料蜂窝。　　蜂窝板结构的设计思想来源工字梁结构：表板相当于工字梁的翼板，主要承受正应力；中间蜂窝层相当于工字梁的腹板，主要承受剪应力…     

受约束蜂窝钢梁在火灾中大挠度变形的数值研究

使用有限元法研究受约束蜂窝钢梁(CSB)在火灾中的大挠度变形。对一种新型的多边形开孔形状的蜂窝钢梁进行研究。有限元模型所给出的承载力通过了实心腹板约束钢梁在火灾高温下的数值结果的验证。蜂窝钢梁的研究参数包括扩张比、腹板开孔大小、腹板开孔形状、腹板开孔位置以及对钢梁的弹性轴向约束。介绍端部反应力的发展、跨中挠度以及高温下受约束蜂窝钢梁临界区域的弯矩。为了让受约束蜂窝钢梁的轴向刚度小于实心腹板钢梁的轴向刚度,火灾中受约束蜂窝钢梁的热伸长所造成的压力要小于实心腹板钢梁的压力。且将较低温度下进入悬链作用阶段的受约束蜂窝钢梁与实心腹板钢梁相比较。结果表明:腹板开孔的大小、形状和位置对火灾中受约束蜂窝钢梁的悬链作用的影响很小。     

火灾下蜂窝钢梁腹板屈曲性能研究

通过有限元方法研究火灾下无防火保护蜂窝钢梁孔间腹板屈曲性能及屈曲温度。首先采用有限元传热分析,获得标准火灾下无防火保护蜂窝梁不同受火时刻的三维有限元温度分析结果,然后采用有限元受力分析确定三维有限元温度分析结果下蜂窝梁孔间腹板的受力性能和屈曲温度。传热分布结果表明,开孔后增加了孔洞周边厚度方向上腹板与空气间的热量交换,使得腹板升温速率明显大于翼缘。火灾下结构受力分析结果表明,由于钢材的力学性能随温度升高而降低,而且中心腹板升温速率快使蜂窝梁更易发生孔间腹板屈曲破坏。蜂窝梁的屈曲温度随孔间距及腹板厚度的增大而增大。通过对采用三维有限元温度分布与均匀温度分布的蜂窝梁进行对比分析,结果表明,由于不均匀温度分布使得沿腹板高度产生附加热应力,从而使得孔间腹板屈曲变形增大。     

蜂窝钢梁孔间腹板屈曲性能研究进展

蜂窝梁因腹板开洞,导致孔间腹板承受复杂的剪力、轴力和弯矩的共同作用,可能发生强度破坏和稳定破坏等多种破坏模式。孔间腹板破坏模式对蜂窝梁受力性能有着显著影响,孔间腹板屈曲承载力计算是蜂窝梁抗剪设计的主要内容。对国内外现有蜂窝梁孔间腹板屈曲问题的研究成果进行了综述,内容包括相关试验研究、理论方法及有限元分析等,分析了相关方法的适用范围及其存在的问题,指出了进一步研究方向。     

ANALYSIS OF SHEAR BEHAVIOR OF STEEL-CONCRETE CELLULAR COMPOSITE BEAM

对腹板开孔后的蜂窝梁和考虑混凝土板组合作用下的蜂窝组合梁抗剪性能进行分析。以试验为基础,建立有限元模型,对不同开孔率、翼缘尺寸、混凝土板尺寸和连接程度下的蜂窝梁和蜂窝组合梁进行分析。结果表明：蜂窝梁翼缘宽度变化对抗剪贡献影响不大,翼缘厚度变化对其影响较大,翼缘厚度的抗剪贡献与开孔大小、形式有关;混凝土板和连接程度对蜂窝组合梁抗剪强度贡献不可忽略。给出了蜂窝梁、无连接蜂窝组合梁和有连接组合梁抗剪强度计算方法;通过分析不同剪跨比蜂窝组合梁的受力性能,给出弯-剪相关曲线公式;通过提高蜂窝组合梁孔洞竖向位置,可以提高其承载能力。     

钢-混凝土蜂窝组合梁抗剪性能分析

对腹板开孔后的蜂窝梁和考虑混凝土板组合作用下的蜂窝组合梁抗剪性能进行分析。以试验为基础,建立有限元模型,对不同开孔率、翼缘尺寸、混凝土板尺寸和连接程度下的蜂窝梁和蜂窝组合梁进行分析。结果表明:蜂窝梁翼缘宽度变化对抗剪贡献影响不大,翼缘厚度变化对其影响较大,翼缘厚度的抗剪贡献与开孔大小、形式有关;混凝土板和连接程度对蜂窝组合梁抗剪强度贡献不可忽略。给出了蜂窝梁、无连接蜂窝组合梁和有连接组合梁抗剪强度计算方法;通过分析不同剪跨比蜂窝组合梁的受力性能,给出弯-剪相关曲线公式;通过提高蜂窝组合梁孔洞竖向位置,可以提高其承载能力。     

圆孔蜂窝梁的弯扭屈曲分析

为了对纯弯状态下圆孔蜂窝梁的弯扭屈曲进行研究,将蜂窝梁翼缘和腹板分离,采用有限元软件ANSYS对蜂窝梁开圆孔腹板进行侧向纯弯分析,由挠度-刚度关系反算侧向刚度,得出开孔腹板相对于实心腹板的刚度折减系数ky。考虑开孔腹板的径高比和距高比,经拟合给出了刚度折减系数ky的计算公式,用该系数对蜂窝梁的自由扭转刚度进行修正,代入实腹工字截面梁弯扭屈曲临界弯矩计算公式,得到蜂窝梁的相应计算公式。最后利用该公式分别对不同跨度、不同孔况的简支蜂窝梁在纯弯状态下的弯扭屈曲临界弯矩进行计算,并与有限元分析结果进行对比。分析结果表明,修正后的临界弯矩计算公式具有较高精度。     

蜂窝梁的稳定性能研究进展

对蜂窝梁破坏模式的研究表明，失稳是其结构性能失效的重要破坏模式。为此，在回顾蜂窝梁结构特性研究的基础上，总结归纳了蜂窝梁失稳的3种主要模式：整体弯扭失稳、梁墩屈曲、畸变屈曲。结合国内外近30多年来对蜂窝梁稳定性的试验研究成果，对影响蜂窝梁稳定性的主要因素进行分析。采用蒙特卡洛法得到纯弯简支蜂窝梁弯扭失稳临界荷载的概率分布和影响因子的敏感度。将部分具有代表性的试验成果与欧洲规范EN 1993-1-1计算结果进行对比，根据中国规范GB 50068—2001《建筑结构可靠度设计统一标准》提供的抗力分项系数，计算了不同荷载组合下蜂窝梁整体弯扭失稳临界荷载的可靠度指标，为国内规范的制订提供依据。最后，总结了当前蜂窝梁稳定性研究中存在的不足，指明了进一步研究的方向。     

蜂窝梁动力特性的有限元分析

以正六边形蜂窝梁为研究对象,利用Rayleigh法对其固有频率进行分析,并用有限元分析软件对蜂窝梁的自由振动进行数值模拟。考虑了不同开孔率、孔口扩高比、高跨比及不同位移约束条件对其固有频率的影响,并与相同截面尺寸的实腹梁以及扩高前的H型钢梁进行对比,结果表明:与原梁相比,蜂窝梁有更出色的抗震性能;大跨度条件下,应用蜂窝梁代替相同截面高度的实腹梁有更好的经济效益。     

Rotational capacity of castellated steel beams

This paper numerically studies the behavior of castellated beams with two simply supported ends under moment gradient loading and investigates the effect of beam and braced lengths on rotational capacity of castellated beams. To assure the ability of numerical models in predicting the complex behavior (especially at the location of opening) as well as the failure modes, numerical models of two experimentally tested specimens are developed. Comparison of force–displacement curves and failure modes shows that neglecting the boundary condition of the specimens, the numerical method can properly predict the behavior of castellated beams. All geometrical properties of the beams are the same as the study parameters so that the finite element model of the corresponding plain‐webbed beams can be easily created by filling the web openings in castellated beams. The accuracy of finite element models of plain‐webbed beams is evaluated by comparing the moment–rotation behavior with that of numerical models developed by other researchers. Rotational capacity of castellated beams derived from numerical models is compared with that of the corresponding I‐shaped plain‐webbed steel beams, and it is observed that in the case of short beams, web openings reduce energy absorption and plastic moment capacity of the beams compared with that of long ones. Copyright © 2012 John Wiley & Sons, Ltd.     

蜂窝梁挠度计算方法研究

蜂窝梁是一种腹板开孔的新型钢梁,与普通实腹梁相比具有节省材料、便于铺设管道、平面内刚度增大、承载能力高等优点,特别适用于现代工业厂房屋盖结构。蜂窝梁由于腹板开孔其抗剪能力降低,与相同截面的实腹梁相比受剪力影响较大,在挠度计算中不仅要考虑剪力引起的剪切挠度还要考虑剪力次弯矩引起的挠度。本文作者以费氏空腹桁架理论为基础,考虑蜂窝梁孔高比和距高比的影响,根据面积等效和惯性矩等效的原则,提出简支蜂窝梁的实用挠度计算公式。以简化计算公式为依据分别对不同蜂窝梁挠度进行计算,同时利用有限元软件AN-SYS对相同条件下的蜂窝梁进行仿真分析,将公式计算结果与有限元分析结果对比,以验证计算公式的准确性。     

钢与混凝土蜂窝形组合梁设计中的若干问题

本文对钢与混凝土蜂窝形组合梁的强度、空腹的次影响、剪力对抗弯强度的影响以及挠度等问题进行了分析,并进行了6组蜂窝形组合梁的试验,为该种结构在徐州彭城电厂中的应用提供了可靠的依据。     

梁腹板开有圆孔时的稳定问题研究

钢梁腹板开孔的局部稳定问题非常重要。本文作者研究了开有圆孔的腹板在剪切、弯矩单独作用下的屈曲应力以及相应的腹板高厚比限值。此外，分析了腹板在剪切、弯矩共同作用下的屈曲问题，得出了用相关公式表示的屈曲条件。     

Interaction of buckling modes in castellated steel beams

This paper investigates the behaviour of normal and high strength castellated steel beams under combined lateral torsional and distortional buckling modes. An efficient nonlinear 3D finite element model has been developed for the analysis of the beams. The initial geometric imperfection and material nonlinearities were carefully considered in the analysis. The nonlinear finite element model was verified against tests on castellated beams having different lengths and different cross-sections. Failure loads and interaction of buckling modes as well as load-lateral deflection curves of castellated steel beams were investigated in this study. An extensive parametric study was carried out using the finite element model to study the effects of the change in cross-section geometries, beam length and steel strength on the strength and buckling behaviour of castellated steel beams. The parametric study has shown that the presence of web distortional buckling causes a considerable decrease in the failure load of slender castellated steel beams. It is also shown that the use of high strength steel offers a considerable increase in the failure loads of less slender castellated steel beams. The failure loads predicted from the finite element model were compared with that predicted from Australian Standards for steel beams under lateral torsional buckling. It is shown that the Specification predictions are generally conservative for normal strength castellated steel beams failing by lateral torsional buckling, unconservative for castellated steel beams failing by web distortional buckling and quite conservative for high strength castellated steel beams failing by lateral torsional buckling.     

负弯矩作用下钢-混凝土组合梁受力性能试验研究

通过8根跨度为3.0m和4.2m的钢-混凝土组合梁在负弯矩作用下的受力性能试验,研究了端部弯矩、跨度、H形钢的腹板高厚比、抗剪连接栓钉数量、设置横向加劲肋等因素对组合梁失稳破坏模式、受弯承载力及转动能力的影响。试验结果表明：对两端部作用数值相等的负弯矩工况,组合梁发生畸变失稳,其受弯承载力小于组合梁全截面塑性弯矩,转动能力偏小,而对其他接近实际结构的负弯矩工况,组合梁发生局部失稳或局部与畸变耦合失稳,其受弯承载力大于组合梁全截面塑性弯矩,转动能力较大;随着腹板高厚比减小或者在腹板上设置横向加劲肋,组合梁的受弯承载力和转动能力都有明显提高。     

Bracing requirements for inelastic castellated beams

Lateral-torsional buckling can be avoided by properly spaced and designed lateral bracing. Bracings are usually assumed to be elastic, and so may be characterized by their elastic stiffnesses. It is well known that an elastic lateral brace restricts partially the lateral buckling of slender beams and increases the elastic buckling moment. However, a full study of the effect of lateral braces on inelastic buckling has not been made especially for castellated beams, and it is not known whether the limiting stiffness for elastic buckling can be applied to castellated beams that buckle inelastically. This paper develops a three dimensional (3-D) finite-element model using a finite-element program and uses it to investigate the effect of elastic lateral bracing stiffness on the inelastic flexural-torsional buckling of simply supported castellated beams with an elastic lateral restraint under pure bending. It was found that for inelastic castellated beams, the effect of bracing initially is increased to some extent as the lateral unbraced length increases and then decreased until the beam behaves as an elastic beam. In other words, the effect of bracing depends not only on the stiffness of the restraint but also on the modified slenderness of the beam. Also, the results show that Winter’s simplified method to determine full brace requirements cannot be applied to inelastic castellated beams. Therefore, a general equation is proposed to determine the value of optimum stiffness in terms of the beam’s slenderness, applicable to all castellated beams under pure bending.