变截面钢梁梁高的确定

材料力学中详细介绍了等截面梁挠度的求法,对变截面梁介绍的甚少。文章从等直梁挠曲线方程入手,以钢梁设计时需满足正常使用极限状态的刚度条件为依据,运用积分方法求解了变截面悬臂钢梁在荷载作用下的挠曲线方程,得出了梁自由端挠度的表达式;通过分析软件ANSYS10.0分析了梁端挠度的变化情况,分析结果表明当梁固端高和自由端高满足特定的条件时,梁端的最大挠度能够满足刚度需求,为工程应用提供了一定的理论依据。     

卷边加强冷弯型钢梁局部和畸变屈曲

设计时,应重点考虑冷弯型钢构件的屈曲特性及其导致的有效性损失,以保证结构的经济性。数值模型改进后,能够反映考虑几何缺陷、材料非线性特性、后屈曲性能等因素的冷弯型钢梁的真实屈曲特性。针对侧向约束下冷成型Z型钢梁,采用已有的有限元模型,研究钢梁卷边及其与受压翼缘的相互作用对后屈曲特性的影响。利用卷边翼缘宽度比以及卷边倾角,观测局部屈曲、畸变屈曲和局部/畸变屈曲相互作用下截面抗弯刚度的变化。评估了EC3中适用于冷成型Z型钢梁局部和畸变屈曲的设计方法的有效性。总体而言,采用EC3计算的截面抗弯刚度并不保守。指出其中的不足并提出改进建议,改善卷边受压翼缘的失稳系数。     

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。     

火灾高温下受约束蜂窝钢梁悬链线效应研究

火灾下受约束钢梁大变形阶段的悬链线效应,考虑了钢梁轴向拉力对抗弯承载力的贡献,可提高钢梁在火灾下的耐火极限。相同截面高度的蜂窝梁,其抗弯刚度与实腹钢梁基本相同,但其轴向刚度却远小于实腹钢梁,因此蜂窝梁火灾下的悬链线效应与实腹钢梁有较大差别。利用有限元方法研究了具有圆角多边形孔的受约束蜂窝钢梁在火灾升温下的悬链线效应。选取荷载比、梁跨度、梁端轴向约束刚度比以及蜂窝梁的扩展比、孔洞高度为主要参数,研究了梁的轴向力、跨中挠度、端部位移以及弯矩等随温度的变化规律。与实腹钢梁相比,火灾下蜂窝钢梁的最大压力较小,更早进入悬链线效应阶段。     

温度作用下连续刚构内力变化规律探讨

用传统结构力学方法,考虑主梁变截面特性的影响,建立了考虑桩土作用的三跨连续刚构在整体温差荷载下的力法典型方程,在上述基础上,就整体温度作用下各控制参数对连续刚构墩梁内力的影响,建立变化关系曲线,并讨论在墩梁刚度比、主梁刚度变化及跨径变化过程中,桥梁控制截面的弯矩变化趋势及规律,可以给设计工作提供一些参考。     

钢筋混凝土柱实腹屋面钢梁结构体系设计中的几个问题探讨

钢筋混凝土柱人字形实腹钢梁结构体系中竖向构件采用钢筋混凝土构件,屋面梁采用实腹钢梁.根据材料性能和结构的受力特性,通过实例计算,分析竖向荷载、水平荷载(风荷载)、屋面坡度、柱子刚度对梁内力、柱内力、柱顶水平位移、结构项部竖向位移、斜梁相对位移的影响,给出了风荷载、屋面坡度和柱截面的合理取值.     

承受轴向、弯曲、剪切和扭曲组合荷载的钢筋混凝土和预应力混凝土的三维数值模型

提出了钢筋混凝土和预应力混凝土承受组合荷载下的分析模型，荷载包括轴力、双向弯矩、扭矩和双向剪力。所提出的模型基于Timoshenko梁理论的简单动力假设，保持了任意截面尺寸情况下的三维框架的形状。框架的控制截面被细分为一维，二维和三维材料响应。钢筋混凝土和预应力混凝土构建的材料模型遵循用切线刚度公式表示的改进压缩场理论的基本假设。     

钢与混凝土联合梁腹板局部稳定性计算

<正> 当联合梁的钢梁或全钢梁的翼缘和腹板的厚度不足时,可能比整根梁丧失整体稳定和强度会更早地丧失稳定或翘曲,这种现象称为丧失局部稳定。本文即介绍联合平台梁的腹板局部稳定性计算方法。一、受力情况联合梁同全钢梁相比,它有个较大刚度的钢筋混凝土翼缘板(图1),同时联合梁的钢梁截面高度较全钢梁低,在承受集中荷载时,联合梁则通过较厚的钢筋混凝土板及钢梁上翼缘板传递荷载,而全钢梁仅由较薄的上翼缘板传递荷载。因此联合梁的腹板较全钢梁的腹板抵抗翘曲的能力强,且可使腹板高度降低,导致腹板减薄,从而可节约钢材。     

考虑开口薄壁断面翘曲刚度的桥梁动力特性实用分析方法

从开口截面桥梁扭转响应控制方程出发,引入开口截面主梁的约束扭转刚度提高系数,建立开口子截面桥梁约束扭转刚度的桥梁动力特性模型计算方法。以某一开口叠合梁截面双塔斜拉桥为例,通过比较未考虑约束扭转刚度的传统单梁式模型、精确的三梁式模型及实用单梁式模型的计算结果,说明未考虑约束扭转刚度的传统单梁式模型不能准确计算桥梁的扭转模态,而实用单梁模型在模拟桥梁扭转动力特性上工程精度满足要求。     

变翼缘宽度钢梁的优化设计

现有的变翼缘宽度钢梁的设计方法只适用于梁受均布荷载的情况。为找到最优的变截面位置,推导了变翼缘宽度钢梁截面优化设计的步骤及通用公式,编写了相应的钢梁截面优化计算机程序。算例表明,变翼缘宽度钢梁的最优截面变更位置是在离梁支座约l/6~l/4的地方,用文中程序设计的钢梁可比手算法节省钢材10%左右。     

Curvilinear fiber optimization tools for design thin walled beams

An investigation of the possible performance improvements of thin walled composite beams through the use of the variable stiffness concept with curvilinear fiber is presented. The beams are constructed from a single-cell closed cross section and a number of non-classical effects such as material anisotropy, transverse shear, warping inhibition and nonuniform torsional model are considered in the beam model. The governing equations were derived by means of the extended Hamilton's principle. Also the extended Galerkin's method is used to solve governing equations. Composite beams subjected to different loading with given geometry and material properties are optimized for maximum failure load. Improvements of variable-stiffness beams over conventional, constant-stiffness beams are also demonstrated.     

受拉边倾斜的钢筋砼梁受剪承载力的解析解

本文将蒋大骅（１９８４，１９８６）提出的基本概念推广到受拉边倾斜的钢筋砼梁，对其受剪承载力进行了研究。提出了力学模式，建立了基本方程，导出了计算公式，并结合试验结果对公式进行了简化。该公式形式比较简单，与试验结果基本符合，当倾角β＝０时，本文公式即为等截面梁的受剪承载力计算公式，达到两者的协调和统一。     

封闭式横截面薄壁组合梁的弯曲—扭转性能

对单室箱形结构中的薄壁复合梁的静力和动力特性进行分析。结构模型中考虑了多种非典型作用，如：材料各向异性、横向剪切、翘曲的抑制作用、非均匀扭转模型和转动惯量。利用扩展的Hamilton原则推导出主导方程，并利用扩展的Galerkin方法进行解释。考虑了纤维方向对静挠度和自然频率的影响，得出一些重要结论。     

Flexural–torsional behavior of thin-walled composite beams with closed cross-section

This paper investigates the static and dynamic characteristics of composite thin-walled beams that are constructed from a single-cell box. The structural model considered herein incorporates a number of nonclassical effects, such as material anisotropy, transverse shear, warping inhibition, nonuniform torsional model and rotary inertia. The governing equations were derived using extended Hamilton's principle and solved using extended Galerkin's method. The effects of fiber orientation on static deflection and natural frequencies are considered and a number of important conclusions are outlined.     

Fire Induced Spalling in High Strength Concrete Beams

A macroscopic finite element model is extended to account for fire induced spalling in high strength concrete (HSC) beams. The model is based on the principles of mechanics and thermodynamics and utilizes pore pressure calculations to predict fire induced spalling in concrete. For validating the model, spalling measurements were made by conducting fire resistance experiments on four normal strength and high strength concrete beams. Spalling predictions from the model are compared with the measured values of spalling at various stages of fire exposure. The validated model is applied to investigate the influence of fire scenario, concrete strength (permeability) and axial restraint on the fire induced spalling and fire response of RC beams. Results from the analysis show that fire scenario, and concrete permeability largely influence the extent of fire induced spalling in concrete beams. Further, it is also shown that the extent of spalling has significant influence on the fire resistance of RC beams.     

Fatigue-loading effect on RC beams strengthened with externally bonded FRP

External bonding of fiber-reinforced polymers (FRP) on concrete beams is particularly attractive for the strengthening of civil engineering structures in order to increase their strength and stiffness. Principles for design of such strengthening methods are now established and many guidelines exist. However, fatigue design procedure is still an ongoing research topic.This paper focuses on the damage behavior of FRP-strengthened reinforced concrete (RC) structures subjected to fatigue loading.In order to design bonded reinforcements, an iterative computational method based on section equilibrium and material properties (concrete, steel, adhesive and composite) has been previously developed by authors [1], [2], [3]. In the present study, this method is extended to describe the fatigue behavior of RC beams.A specific modeling coupled with an experimental investigation on large-scale beams made it possible to compare the theoretical and experimental fatigue behaviors of RC beams with and without composite reinforcements. The model is developed and calibrated using data of the literature or recorded during experiments specifically carried out for this study. Results showed that the beam deflection and the strain in each material could be calculated with a sufficient accuracy, so that the fatigue behavior of the FRP-strengthened beams was correctly estimated by the model.     

GFRP与CFRP加固T形截面RC外伸梁抗剪强度之比较

试验研究了T型截面混凝土外伸梁负弯矩区段采用U形粘贴玻璃纤维布（GFRP）与碳纤维布（CFRP）进行抗剪加固时,在不同的加固形式下,梁斜截面的受力性能和破坏特征,并对其机理进行了初步分析。比较了梁负弯矩区段分别采用GFRP加固和CFRP加固时其抗剪强度之差异。     

带构造柱加圈梁小型混凝土砌块砌体抗剪强度分析

本文在参考文献的基础上，利用基床系数法的原理，对在竖向荷载作用下圈梁和砌体所承担的竖向荷载进行了分析，得出了圈梁和砌体各自承担的竖向荷载的分配系数。并利用相互作用协调变形的原理，结合试验数据，对在水平荷载作用下，构造柱和砌体所承担的水平荷载进行了分析，得出了构造柱和砌体各自承担的水平荷载的分配系数。并进行了算例分析，得出了一些规律性的结论。     

锈蚀钢筋混凝土梁承载能力分析的变角桁架模型

为了研究侵蚀环境下锈蚀钢筋混凝土梁在长期荷载作用下的承载能力，以荷载作用下锈蚀钢筋混凝土梁为研究对象，分析了钢筋锈蚀对混凝土梁黏结强度的影响，基于拉-压杆模型和标准桁架模型分别对锈蚀梁进行了承载力计算，进一步采用考虑钢筋锈蚀影响的修正变角桁架模型计算锈蚀钢筋混凝土梁的承载力，并通过49组锈蚀混凝土梁的试验数据对建议模型进行验证。结果表明：锈蚀钢筋混凝土梁承载力的试验值与变角桁架模型理论计算值之比的平均值为0.990，方差为0.071，二者吻合较好。采用变角桁架模型可精确计算锈蚀钢筋混凝土梁的承载力并预测其破坏模式，建议模型可用于锈蚀钢筋混凝土梁承载能力分析研究。     

Lateral-torsional buckling resistance of coped beams

The lateral-torsional buckling resistance of beams depends on the support conditions. In floor structures for buildings coped beams are often used. A numerical model was developed to investigate the influence of copes on the lateral buckling resistance. This model is described in a companion paper [Maljaars J, Stark JWB, Steenbergen HMGM, Abspoel R. Development and validation of a numerical model for buckling of coped beams. Journal of Constructional Steel Research 2005;61(11):1576-93]. In this paper results of a parameter study carried out with the numerical model are presented. Based on these results recommendations for design rules are given. The study is restricted to (coped) beams with end plates.