残余应力对等截面H型钢梁相关屈曲的影响分析

以有限元分析软件ANSYS为工作平台,基于非线性板壳有限元分析理论,采用大挠度弹塑性分析方法,对轻型门式刚架中H型钢梁相关屈曲性能进行了深入的研究,主要考察了残余应力对等截面H型钢梁相关屈曲性能的影响,获得到了一些有价值的结论。     

残余应力对H型钢楔形梁相关屈曲的影响

以有限元分析软件ANSYS为工作平台,基于非线性板壳有限元理论,采用壳单元对轻型门式刚架中H型钢楔形薄壁梁进行考虑双重非线性的全过程分析,从而对其相关屈曲性能进行深入的研究。通过变化构件腹板厚度、长度、翼缘宽度、楔率等几何参数,从荷载-位移曲线、承载力、变形的发展等方面入手,分析了残余应力对变截面H型钢梁的相关屈曲性能的影响,获得到了一些有价值的结论。     

不同荷载工况下双段变截面H型钢梁相关屈曲性能分析

采用ANSYS软件中的板壳元,考虑双重非线性,对梁端受等弯矩、不等同号弯矩、不等异号弯矩和梁上均布荷载和两端简支与固接情况下双段变截面H型钢梁进行了全过程分析,并同时考虑了纵向焊接残余应力、初始几何缺陷的影响。根据获得的构件荷载-位移曲线和不同荷载时刻的构件整体与局部变形形态,对比分析了不同荷载工况对双段变截面梁的承载力、整体刚度、相关屈曲、塑性扩展等性能的影响。研究结果表明,对于受弯矩作用的双段变截面H型钢薄壁梁,其腹板宽厚比可尽量取大值;剪力对梁的相关屈曲性能影响很大,对主要受剪力作用的梁,要防止发生腹板局部屈曲;固接约束极大改善构件性能。     

变截面H型钢柱相关屈曲性能研究

采用板壳单元离散变截面H型钢柱,并同时考虑构件整体与局部初始缺陷、残余应力、材料屈服、几何非线性等因素的影响。根据数值分析的结果,重点研究了腹板宽厚比、腹板楔率、翼缘宽厚比、长细比等参数对板件局部屈曲与构件整体稳定的影响,总结了压力作用下变截面H型钢柱局部屈曲、整体屈曲和相关屈曲的发展过程以及影响因素。     

国际期刊导读

具有不确定材料性能的壳结构非线性有限元分析;冷弯钢构件残余应力和应变的预测;薄壁开口构件的屈曲分析——有限元公式;薄壁梁的非线性有限元分析;通宽剥离时复合板材的后屈曲性能     

带有残余应力的钢梁内嵌式预应力组合梁抗火性能研究

为研究残余应力对钢梁内嵌式的预应力简支组合梁在火灾效应下的受力性能的影响,通过ABAQUS软件建立钢梁内嵌式的预应力简支钢-混组合梁几何非线性和材料非线性的有限元模型,利用热力-耦合法计算组合梁在高温下的结构响应行为。通过对梁的截面温度、整体挠度和跨中挠度、跨中截面应力分布、拉索应力和塑性变形、梁的整体曲率和跨中曲率等特性在高温下的结构响应进行考察,探究工程应用中常见初始残余应力对组合梁的影响机理。结果表明：残余应力主要是通过影响钢梁的截面模量,进而对钢梁的截面抗弯刚度产生影响,在升温后期或当钢梁开始进入塑性状态时,残余应力的影响逐渐减小。残余应力在钢梁腹板上的分布能较为明显的影响组合梁的承载能力,分布形式不同影响效果也不同。残余应力主要影响了组合梁中钢梁的截面刚度,进而也影响了组合梁的挠度幅度、曲率分布、中和轴高度以及拉索内力变化。     

H型钢楔形薄壁梁相关屈曲性能分析

以有限元分析软件ANSYS为平台,基于非线性板壳有限元分析理论,对轻型门式刚架中H型钢楔形薄壁梁的相关屈曲性能进行大挠度弹塑性分析。用Shell 18l单元对轻型门式刚架中H型钢楔形薄壁梁进行离散,考虑初始几何缺陷和残余应力的影响,对其进行全过程跟踪分析,从而对其相关屈曲性能进行深入的研究。从荷载-位移曲线、承载力、变形的发展和塑性区的分布等方面入手,对影响相关屈曲性能的因素(腹板高厚比、翼缘宽厚比、跨度、楔率等)进行系统的分析和研究,并与现行规范进行比较,得到一些有价值的结论。     

初始残余应力对预应力钢-混凝土连续组合梁抗火性能影响

为研究钢梁残余应力对预应力连续组合梁抗火性能的影响,建立了预应力连续组合梁在高温下非线性升温过程受力行为的有限元模型。通过考察梁的破坏形式、跨中挠度、预应力拉索张力、截面弯矩以及梁的曲率等关键参数随温度的变化,得到不同残余应力模式对组合梁抗火性能的影响机理。分析结果表明：残余应力的分布并不总是对预应力钢-混凝土组合梁的高温性能产生不利影响,腹板具有初始残余拉应力分布模式的预应力钢-混凝土组合梁高温下的挠度相对最小;残余应力主要通过影响截面正应力分布来影响钢梁的截面刚度;在临界状态时,残余应力对组合梁截面刚度的影响不明显;不同残余应力模式对高温下预应力钢-混凝土组合梁的截面抗弯刚度影响不同;当预应力钢-混凝土组合梁的初始残余应力模式以腹板全截面拉应力为主时,预应力钢-混凝土组合梁跨中截面抗弯刚度最大;当残余应力对组合梁跨中截面抗弯刚度有利时,梁跨中截面处中和轴位置比无残余应力影响时较高。     

高强钢焊接工字形截面梁整体稳定性能分析

为了研究不同残余应力分布模式和钢材强度等级对焊接工字形截面梁整体稳定性能的影响,采用ANSYS有限元软件建立了有限元模型,通过与相似试验的对比,证明了有限元模型的正确性。在此基础上对屈服强度为235 MPa,345 MPa和460 MPa的钢梁分别进行考虑残余应力和不考虑残余应力的有限元分析,结果表明,残余应力会使钢梁整体稳定性能降低;钢梁整体稳定承载力会随着钢材强度的提高而提高。     

折线形腹板钢梁静力非线性有限元分析

把工字形钢梁腹板加工成折板,是提高腹板抗屈曲能力的一种途径,考虑几何非线性和材料非线性,对折线形腹板钢梁和设置腹板加劲肋的钢梁进行了有限元分析,研究了折线形腹板钢梁的受力性能及钢梁应力和挠度的发展过程.研究表明,折线形腹板相邻板件互为支承,明显提高了腹板屈曲承载力,但屈曲后强度的提高不如设置加劲肋的腹板,钢梁有限元分析结果和实测值比较吻合.     

Lateral buckling strengths of cold-formed rectangular hollow sections

Code rules for designing steel beams against lateral buckling which are based on data for hot-rolled I-sections are unnecessarily conservative when used for cold formed rectangular hollow section beams.Cold-formed rectangular hollow section beams have different stress-strain curves, residual stresses, and crookedness and twist. The effects of residual stress on the inelastic buckling of I-section beams are not nearly as pronounced for hollow sections with two webs, while the strengthening effects of pre-buckling deflections are greater for hollow sections. Simplistic code rules for top flange loading are very conservative when applied to hollow sections.This paper reviews elastic lateral buckling behaviour and the strength rules used to design steel beams. It develops realistic models for cold-formed rectangular hollow beams which are analysed to predict the effects of moment distribution, load height and yield stress on their strengths. The results of the analyses are used to develop improved design rules which remove much of the conservatism of present design rules.     

Numerical investigation of inelastic buckling of steel–concrete composite beams prestressed with external tendons

The ultimate resistance of a continuous composite beam is governed by either distortional lateral buckling or local buckling, or an interactive mode of the two which is sharply different from the torsional buckling mode in a bare steel beam. A finite element model is developed and based on the proposed FE model, inelastic finite element analysis of composite beams in negative bending is investigated, considering the initial geometric imperfection and the residual stress patterns and the FE results are found agree well with the test results. Parametrical analysis is carried out on the prestressed composite beams with external tendons in negative bending. Factors that influence load carrying performance and buckling moment resistance of prestressed composite beams are analyzed, such as initial geometric imperfection, residual stress in steel beams, force ratio, which is defined as the extent of prestressing force and negative reinforcement in the beams, as well as the slenderness ratios of web, flange, and beams. By varying cross-section parameters, 25 groups of composite beams under negative uniform bending with initial geometric imperfection, residual stress as well as different force ratios, 200 beams in total are studied by means of the FE method. The computed buckling moment ratios are drawn against the modified slenderness proposed by the authors and compared with the Chinese Codified steel column design curve. It is demonstrated that the tentative design method based on the Chinese Codified design curve can be used in assessment of buckling strength of composite beams in a term of the modified slenderness defined.     

残余应力分布对焊接不锈钢工字形截面梁整体稳定性能的影响

焊接残余应力导致不锈钢梁截面纤维过早达到屈服,并严重降低不锈钢梁的抗弯刚度。为了研究残余应力对焊接工字形不锈钢梁侧扭屈曲的影响,根据目前被广泛采纳的不锈钢工字形截面残余应力分布模型,采用有限元方法,对残余应力分布模型的主要因素进行参数化分析,研究这些因素对不锈钢梁侧扭屈曲的影响,使对焊接工字形不锈钢梁的整体稳定性能的研究更加完善。结果表明:翼缘残余压应力峰值对不锈钢梁侧扭屈曲的影响最为显著。     

Proposed residual stress model for roller bent steel wide flange sections

The manufacturing process of structural wide flange steel sections introduces residual stresses in the material. These stresses due to hot-rolling or welding influence the inelastic buckling response of structural steel members and need to be taken into account in the design. Based on experimental data standardized residual stress models have been proposed for inclusion in inelastic buckling analyses. By incorporating these residual stress models their effect on the resistance of beams and columns can be obtained. Residual stress models for roller bent steel sections are currently not available. Roller bent wide flange sections are manufactured by curving straight members at ambient temperature. This manufacturing technique, which is also known as roller bending, stresses the material beyond its yield stress, thereby overriding the initial residual stresses prior to bending and generating an entirely new pattern. This paper proposes a residual stress model for roller bent wide flange sections, based on earlier conducted numerical investigations which were validated by experimental research performed at Eindhoven University of Technology. The proposed residual stress model can serve as an initial state of a roller bent steel section in fully non-linear finite element analyses to accurately predict its influence on the inelastic buckling response.     

考虑栓钉滑移效应及钢筋作用的组合梁受力分析

为研究钢-混凝土组合梁在静载作用下的力学性能,建立一个考虑栓钉滑移及钢筋作用的有限元分析模型;结合算例对开/闭口组合梁的抗弯性能,裂缝发展趋势及分布特征进行比较,混凝土及钢梁的应力-应变关系曲线计算结果与输入曲线吻合良好。     

不同斜卷边檩条的局部屈曲和畸变屈曲

利用Hancock的简化模型分析了卷边槽形、卷边Z形檩条的畸变屈曲,用有限元方法计算了卷边槽形、卷边Z形檩条的畸变屈曲荷载以及翼缘局部屈曲系数,研究了卷边角度对畸变屈曲荷载的影响,提出斜卷边加劲板的屈曲系数取值以及屈曲系数关于卷边角度变化的公式。经对比验证,在卷边角度40°～90°的范围内,误差在2%以内。可供实际设计参考。     

Lateral–torsional buckling of cold-formed channel sections subject to combined compression and bending

This paper presents an analytical study of the flexural buckling and lateral–torsional buckling of cold-formed steel channel section beams subject to combined compression and bending about their major and minor axes. For channel section beams a bending about the minor axis creates a non-symmetric pre-buckling stress distribution, which has a significant influence on the lateral–torsional buckling of the beams. This kind of feature has not been discussed in the existing literature. The focus of this present study is the interaction between the compression load and the bending moments about the major and minor axes. It has been found that for a section subject to combined compression and the major-axis bending the bending moment will decrease the critical compression load, although the critical value of the largest compressive stress in the section actually increases with the applied bending moment. However, for a section subject to combined compression and the minor-axis bending the effect of the bending moment on the critical compression load depends on the direction of bending applied. For bending that creates a compressive stress in the lips the bending moment will reduce the critical compression load. However, for bending that creates a compressive stress in the web the bending moment has almost no influence on the critical compression load.