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。     

Experimental study on residual stresses in welded monosymmetric I-section

为了研究单轴对称焊接工字形截面残余应力分布规律,采用盲孔法对15个单轴对称工字形截面试件进行了试验研究,得到了不同试件全截面纵向残余应力分布,研究了腹板高厚比、翼缘宽厚比、翼缘宽度、施焊顺序等对残余应力的影响。试验结果表明：残余压应力数值与截面尺寸直接相关,残余拉应力数值受截面尺寸影响较小;腹板中靠近宽翼缘一侧的残余压应力峰值大于靠近窄翼缘一侧的压应力峰值;翼缘宽度增大时,分布于所在翼缘和腹板的残余压应力减小;施焊顺序对翼缘上的残余应力及腹板上的残余拉应力峰值有一定影响,而腹板上的残余压应力没有明显变化。基于试验结果,提出了适用于单轴对称焊接工字形截面的残余应力分布模型,该模型能够较准确反映各种因素的影响。     

单轴对称焊接工字形截面残余应力试验研究

为了研究单轴对称焊接工字形截面残余应力分布规律,采用盲孔法对15个单轴对称工字形截面试件进行了试验研究,得到了不同试件全截面纵向残余应力分布,研究了腹板高厚比、翼缘宽厚比、翼缘宽度、施焊顺序等对残余应力的影响。试验结果表明:残余压应力数值与截面尺寸直接相关,残余拉应力数值受截面尺寸影响较小;腹板中靠近宽翼缘一侧的残余压应力峰值大于靠近窄翼缘一侧的压应力峰值;翼缘宽度增大时,分布于所在翼缘和腹板的残余压应力减小;施焊顺序对翼缘上的残余应力及腹板上的残余拉应力峰值有一定影响,而腹板上的残余压应力没有明显变化。基于试验结果,提出了适用于单轴对称焊接工字形截面的残余应力分布模型,该模型能够较准确反映各种因素的影响。     

工字形等截面悬臂横梁弯扭失稳问题解析解研究

推导了工字形等截面(双轴对称等截面和单轴对称等截面)悬臂横梁的弯扭失稳问题的解析解,与有限元程序ANSYS得到的数据进行对比,验证了推导解析公式的有效性。研究结果表明:对于双轴对称工字形等截面悬臂横梁,解析公式与ANSYS数值分析结果吻合较好,对于单轴对称截面则相对误差较大,分析了产生误差的原因。     

组合双轴对称工字形钢梁截面优化设计

提出双轴对称钢梁截面设计中判别强度控制和刚度控制的临界跨高比的概念,并推导了组合双轴对称工字形钢梁在不同腹板高厚比下的腹板高度与截面模量、截面惯性矩的关系式。在此基础上,给出了组合双轴对称工字形钢梁截面的优化设计步骤,并根据算例对优化设计步骤进行验证。算例结果表明,该优化步骤是快速与准确的,优化效果明显,可方便地应用于组合双轴对称工字形钢梁截面的设计。     

MATLAB优化工具箱在钢结构截面优化中的应用

利用MATLAB优化工具箱对钢结构截面进行优化 ,具有结果可靠、方便快捷等优点。通过对单、双轴对称组合工字形梁截面的优化结果的分析 ,提出了在不同情况下 ,该两种组合工字形梁各自的适用条件。     

薄壁钢梁中的横向正应力及其对强度和稳定性的影响

对工字形钢梁在横向分布和集中荷载作用下 ,各板件内的横向正应力进行了分析和比较 ,指出了在支座截面和跨中集中荷载作用截面 ,有时必须考虑这个横向正应力的影响。还对横向正应力对钢梁整体稳定性的影响采用板件稳定理论的方法进行了研究 ,并发现它对单轴对称截面的钢梁 ,在横向荷载作用下的稳定性有很大的影响。提出的钢梁稳定理论的新的表述 ,证实了传统的稳定理论 ,并且与采用ANSYS板壳单元进行的稳定性分析结果一致     

大跨结构箱形曲梁的平面内整体稳定性能分析

为研究两端铰接圆弧轴线箱形截面曲梁的平面内整体稳定性能,采用数值方法对其进行了理论研究,采用ABAQUS有限元软件建立了二维的曲梁模型,模拟曲梁的平面内稳定问题。研究了不同圆心角、不同长细比,以及不同大小的初始几何缺陷对圆弧轴线箱形截面曲梁平面内稳定性能的影响,得到了弹性屈曲系数的数值解与经典理论解的差异和规律,给出了初始几何缺陷对稳定系数和正则化长细比关系曲线的影响,并且计算得到了该形式曲梁的轴力-弯矩关系曲线。提出的圆弧轴线箱形截面曲梁平面内稳定的设计公式可为今后的设计提供理论依据和建议。     

任意开口薄壁截面圆弧曲梁弯扭精确分析

现有薄壁曲梁弯扭理论缺乏严密的理论推导。本文基于薄壁构件分析的两个基本假定，导出了任意开口薄壁截面圆弧曲梁的翘曲位移、正应力、剪应力及其各自合力以及平衡微分方程的精确表示式。为便于应用，本文还给出了一套具有良好精度的内力简化公式及相应的平衡微分方程。     

焊接工字形钢曲梁的极限承载力试验

针对目前曲梁承载力方面的研究比较缺乏 ,进行了 18根焊接工字形水平钢曲梁的极限承载力试验。通过试验研究 ,了解水平钢曲梁在弹塑性阶段的工作特性 ,给出每个构件的荷载 -位移曲线和极限承载力 ,得到了曲梁承载力随跨长、曲率半径以及截面尺寸的变化规律。同时将试验结果与有限元分析的结果进行比较 ,在考虑端部翘曲约束的情况下 ,两者符合较好。     

大跨度钢筋混凝土平面曲梁分析与设计

以某体育场大跨度钢筋混凝土平面曲梁为例,利用ANSYS对曲梁的截面进行分析优化。首先分析曲梁变形对其他周边构件的影响,其次通过参数化分析确定曲梁最优截面形式为箱形截面并且分析得到了最优截面尺寸。最后对整体结构进行静力和动力分析。结果表明,对梁截面进行优化后能够使整体结构达到一个较为理想的受力状态。     

Cold curving symmetric unstiffened I-girders

Horizontally curved steel girders are usually fabricated using cut curving or heat curving. Cut curving results in excessive waste while heat curving is a trial and error process that can be time consuming. In contrast, cold bending is a simple, versatile, economical procedure in which the required curvature is directly obtained by applying loads. As most cold bending systems developed are proprietary, little published information is available and progress has been stymied. Recently, an innovative cold bending system was developed for fabricating curved steel girders used in the construction of the Miami Metromover. This paper presents a simplified analysis for this system for curving symmetrical, un-stiffened girders. A systematic practice-based curving procedure is proposed and its application illustrated by three inter-related numerical examples.     

Analysis of equal leg single-angle section beams subjected to biaxial bending and constant axial compressive force

Single-angle section beams are generally loaded parallel to their geometrical axes and their cross-sections are not symmetrical to their principal axes. Even equal leg angle beams have only one symmetrical axis. Many types of loading cause biaxial bending and axial forces in these members. Since single-angle section beams are slender members, they also need to be analyzed in terms of flexural buckling, lateral torsional buckling and local buckling effects. In this study, a calculation procedure is presented to analyze the nominal loads of equal leg angle section beams loaded vertically to the axis of the beam. It is assumed that the axial force is composed of a constant compressive force. The constant axial force is only taken into consideration for the uniform compressive stress and the second-degree effects caused in the cross-section. Thus only the biaxial bending moments remain. The first yield, full plastic and critical lateral torsional buckling moments for biaxial bending are calculated with respect to the slenderness of the beam and the axial force. The nominal design force on the cross-section is calculated according to the load and resistance factor design rules. The analysis proposed for the constant axial load can also be used for other axial forces, by using an iterative calculation procedure.     

Optimization of open cross section of the thin-walled beam with flat web and circular flange

This paper is devoted to cold-formed thin-walled beams with open cross section. The beam cross section is optimized for a fixed cross section area under strength and stability constraints. Optimal geometrical parameters of the cross section are determined with regard to maximal and safe bending moment. The strength condition is a classical condition applied to the theory of beams for assumed allowable stress. The stability condition serves also as a classical condition for lateral buckling, taking the warping torsion into account. Moreover, the thin-walled beams have been analyzed, for which the shear center, i.e. the main pole, is located in the centroid of the cross section. Results of the numerical analysis are given. Figures present examples of optimal cross sections of the thin-walled beams.     

双肢拼合冷弯薄壁型钢工字形截面梁受弯性能研究

对6个单肢冷弯薄壁型钢C形截面梁和18个双肢拼合冷弯薄壁型钢工字形截面梁进行了受弯性能试验研究 ,考察梁跨高比、翼缘宽厚比、截面高宽比、螺钉连接间距以及腹板开孔对双肢拼合工字形截面梁破坏模式和极 限受弯承载力的影响,验证双肢拼合截面梁受弯承载力具有“1×2≥2”的拼合效应,并采用ANSYS有限元软件进 行数值模拟与影响因素分析。结果表明：试件的破坏模式为翼缘及腹板局部屈曲和畸变屈曲的相关屈曲形式。改 变翼缘宽厚比和截面高宽比对双肢拼合冷弯薄壁型钢工字形截面梁的承载力影响最大,而改变螺钉连接间距 （300~600mm范围内）和梁跨高比对工字形梁的承载力影响较小。在实际工程设计中,建议腹板开孔采用圆形孔 洞形式,腹板开孔截面积比例取为35%~50%之间,同时腹板开孔间距应不小于400mm。在双肢拼合工字梁受弯承载 力折减强度法的基础上,提出了适用于腹板开孔双肢拼合冷弯薄壁型钢工字形截面梁受弯承载力计算的强度折减 修正法。     

钢管混凝土柱—弧形钢箱梁框架结构细部节点做法探讨

厦门港国际旅游客运码头客运联检大楼屋面为六片双曲钢结构屋面,屋盖钢结构采用钢管混凝土柱-弧形钢箱梁框架结构。本文探讨了屋盖弧形箱梁曲线形状的设计要点,以及弧形箱梁主次梁交接处、梁柱节点、柱脚的细部做法。     

型钢加固钢筋混凝土梁的受力分析

通过对型钢加固钢筋混凝土梁的受力分析,依据所作的基本假定分析了加固前后梁截面的应变及应力变化,推导了加固前后梁的承载力、型钢与梁间剪应力以及加固梁抗弯刚度的计算式;得出型钢加固钢筋混凝土梁可大幅度提高梁的抗弯能力,同时也有效提高梁抗弯刚度的结论;最后提出对加固材料性能和加固前梁上荷载的定性要求。     

Experimental study on curved composite beams subjected to combined flexure and torsion

There are situations in which a composite steel–concrete beam is subjected to torsion, such as members that are curved in plan or straight edge beams. The concrete slab and steel beam contribute to the torsional strength and stiffness of a composite steel–concrete beam, but this composite action is usually ignored in design codes of practice, which leads to conservative designs. Therefore, this paper investigates the ultimate strength of curved in place composite steel–concrete beams. Eight curved in plan composite steel–concrete beams have been tested under a single applied load at mid-span. Partial shear connection has also been considered in these tests. The composite steel–concrete beams have been designed with different span/radius of curvature ratios. This paper further supports the view that, in the presence of flexure, there will be an increase in the torsional moment capacity, but the flexural moment capacity does not greatly increase in the presence of torsion. A model has also been presented to represent the bending–torsion interaction for curved in plan composite steel–concrete beams with full and partial shear connection.     

Mechanical analysis of circular liners with particular reference to composite supports. For example, liners consisting of shotcrete and steel sets

This paper describes a methodology for the mechanical analysis of composite supports, such as liners consisting of shotcrete and steel sets. The methodology presented here is based on an established technique of structural analysis commonly referred to as the ‘equivalent section’ approach. This technique consists in treating the composite section of a straight beam as a homogenized section of equivalent mechanical properties. The equations presented in this paper have been derived from application of the theory of elastic shells (or curved beams) and therefore are more appropriate for the analysis of circular tunnel liners. The proposed methodology for the design of liners is based on the construction of capacity diagrams, another established technique of structural analysis and concrete design that can be conveniently extended to the analysis of composite sections for tunnel liners. When applying the theory of elastic shells to derive the equations that conform to the proposed methodology, the problem of determining the mechanical response of semi-circular arches treated with the theory of thin and thick formulations has been re-visited. Observations of practical interest arising from the comparison of results obtained with both approaches are discussed.     

A new buckling theory for curved beams of solid cross sections derived from rigid body and force equilibrium considerations

A new method is proposed for deriving the instability potential of initially stressed curved beams based on the rigid body and equilibrium considerations using the updated Lagrangian formulation. Starting from the rigid body rule, the virtual instability potential was derived for a spatially curved beam under real rigid displacements. Next, utilising the equilibrium equations for the boundary forces at the C₁ and C₂ states, another virtual instability potential was derived for the curved beam under virtual rigid displacements. Comparing the two potentials yields the one in total form for the curved beam. The present approach requires only simple integrations and analogical comparison of related virtual works, thereby avoiding the physically unclear, complicated derivations involved in previous procedures. Based on the first principles of rigid body rule and equilibrium, the derived potential energy is more concise than the conventional approach that requires the consideration of six stress components in the formulation. As an illustration, the present theory was successfully adopted in the buckling analysis of helical curved beams under radial loads.