钢－混凝土组合梁非线性有限元分析

提出了部分剪力连接钢-混凝土组合梁非线性有限元分析的简化模型，该模型同时考虑了钢、混凝土材料的非线性本构关系和剪力连接件的滑移非线性对组合梁刚度和强度的影响，推导了考虑滑移的剪力连接件单元刚度矩阵。利用该模型计算了连续组合梁的极限荷载、挠度、应力以及滑移，与已有的理论计算结果和实验结果吻合，证明本方法分析钢-混凝土组合梁非线性的可靠性和实用性。     

部分共同作用框架组合梁有限元分析模型

本文提出了一种新的适用框架整体分析的组合梁有限元模型。在分析了相互作用程度对组合梁刚度影响的基础上,根据Newmark等人的一维部分相互作用理论,建立起部分共同作用组合梁平衡微分方程;结合框架组合梁受力特点引入合理的边界条件,推导出了能够考虑滑移的组合梁单元弹性刚度方程;还给出了常见非节点荷载的等效荷载公式。该组合梁单元节点自由度少,每个构件只需一个单元来模拟,方便了带组合梁钢框架的结构分析。本文的研究还为进一步地考虑混凝土开裂、压碎,钢材屈服等非线性因素,建立组合梁单元弹塑性刚度矩阵提供了理论基础。     

钢-混凝土组合梁桥徐变的三维虚拟层合元分析

采用三参数粘弹性模型,对钢-混凝土组合梁桥在长期荷载作用下的徐变性能进行了研究,并采用三维虚拟层合单元法研究这种效应以及截面由不同材料组成时结构的受力特点。在实验研究的基础上,拟合了粘弹性模型中的参数,并对钢-混凝土组合梁桥在长期荷载作用下的竖向变形和轴向应变进行了研究,通过对计算和试验结果进行对比分析验证了该法的准确性。     

新型外包钢-砼组合梁的受力性能分析

针对普通钢-混凝土组合梁存在的一些问题，提出了一种新型的组合梁——外包钢-混凝土组合梁。为了研究其受力性能，进行了三根足尺简支梁的试验研究，并通过对构件荷载-位移曲线、荷载-应变曲线和应变沿截面高度分布的分析，认为外包钢-混凝土组合梁有较优越的力学性能和良好的应用前景。基于组合梁弹塑性理论，推导出梁的正截面承载力的计算公式，与试验结果比较吻合。最后，为了便于其工程中的应用，根据试验结果，提出了适于该种组合梁的一些构造措施。     

钢-混凝土组合梁收缩徐变效应的随机分析

钢-混凝土组合梁是由混凝土板和钢梁通过剪力键连接而成的组合结构。由于混凝土的收缩徐变,将引起结构内力和应力重分布。混凝土收缩徐变具有离散性大的特点,进而导致结构长期响应表现出随机性。本文综合考虑徐变模型、收缩模型、混凝土抗压强度、混凝土弹性模量、环境湿度、钢材弹性模量、荷载以及剪力键刚度的随机性对钢-混凝土组合梁结构响应的影响。利用拉丁超立方抽样技术和基于响应面方法的蒙特卡洛抽样,研究了钢-混凝土组合梁挠度和应力时变效应的概率问题。     

钢-混凝土组合梁收缩徐变效应的随机分析

钢-混凝土组合梁是由混凝土板和钢梁通过剪力键连接而成的组合结构。由于混凝土的收缩徐变,将引起结构内力和应力重分布。混凝土收缩徐变具有离散性大的特点,进而导致结构长期响应表现出随机性。本文综合考虑徐变模型、收缩模型、混凝土抗压强度、混凝土弹性模量、环境湿度、钢材弹性模量、荷载以及剪力键刚度的随机性对钢-混凝土组合梁结构响应的影响。利用拉丁超立方抽样技术和基于响应面方法的蒙特卡洛抽样,研究了钢-混凝土组合梁挠度和应力时变效应的概率问题。     

新型外包钢混凝土组合梁框架结构抗震性能的试验

为克服型钢混凝土柱-钢梁组合框架结构体系存在的缺点,提出了一种新型外包钢混凝土组合梁-型钢混凝土柱组合框架结构体系。设计制作了一榀一跨两层型钢混凝土柱-外包钢砼梁的组合框架结构模型,并通过施加恒定竖向荷载和低周反复水平荷载,对模型框架进行了抗震性能试验研究。结果表明,基于现行规范及作者新研究外包钢组合梁计算理论所设计的型钢混凝土组合框架在地震时能形成梁铰破坏机制,框架的变形能力、承载能力、延性、耗能能力等均满足延性框架的抗震要求,且模型框架的有效延性系数达到了7.93。可见,新型型钢混凝土组合柱-外包钢混凝土组合梁框架结构的抗震性能优于钢框架结构和型钢混凝土柱-钢梁框架结构,可在高层建筑中应用。     

基于并行计算和遗传算法的钢-UHPC华夫板组合梁优化设计

为实现钢-超高性能混凝土(UHPC)华夫板组合梁结构快速经济合理的设计，提出了基于并行计算与遗传算法的结构优化设计方法。通过Python建立了并行计算平台，使Abaqus和Python能够执行同步数值模拟和数据处理，以成本最小化为目标，采用遗传算法对钢-UHPC华夫板组合梁进行了优化，验证了所提方法的可行性。结果表明，遗传算法中密集的分析任务可以并行化并分配给不同的计算资源以提高计算效率；使用并行计算可以提高8.6倍的优化效率；并行计算和串行计算的CPU平均使用率分别为82%和18%。本文方法的成功应用可为其他类型结构的优化设计提供参考。     

钢结构框架中组合梁等效刚度的确定方法

刚接或半刚性连接的组合梁在荷载作用下，在梁的长度范围内既有正弯矩作用段，又有负弯矩作用段，由于组合梁截面在正弯矩作用和负弯矩作用下截面抗弯刚度不一致，因而在弯矩为零的点处梁的截面抗弯刚度发生突变，而组合梁框架分析的关键是确定组合梁刚度突变分界点的位置及确定在整体分析中所采用的等效梁的刚度。本文根据应变能相等的原理对钢结构框架中组合梁的等效抗弯刚度进行了研究，推导了其等效刚度的表达式，并给出不同荷载作用形式下刚接框架组合梁等效刚度简化计算公式，为组合梁钢框架的整体分析提供了便利。最后分析了水平荷载以及梁柱连接特性对组合梁等效刚度的影响，分析结果表明，采用本文提出的组合梁等效刚度进行半刚性连接框架整体分析偏于安全。     

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在考虑组合梁的交界面滑移和掀起引起的连接件变形的基础上,给出了一种方便设计使用的简化分析方法,以钢上层梁组合梁为例,进行了验算分析,证明此方法的正确性．     

压电层合梁静动力学分析的高精度梁单元

给出了一个对复合材料压电层合梁进行数值分析的高精度压电层合梁单元。基于Shi三阶剪切变形板理论的位移场和Layer-wise理论的电势场,用力-电耦合的变分原理及Hamilton原理推导了压电层合梁单元列式。采用拟协调元方法推导了一个可显式给出单元刚度矩阵的两节点压电层合梁单元,并应用于压电层合梁的力-电耦合弯曲和自由振动分析。计算结果表明,该梁单元给出的梁挠度和固有频率与解析解吻合良好,并优于其它梁单元的计算结果,说明了本文所给压电层合梁单元的可靠性和准确性。研究结果可为力-电耦合作用下压电层合梁的力学分析提供一个简单、精确且高效的压电层合梁单元。     

STOCHASTIC BOUNDARY ELEMENT METHOD FOR RELIABILITY ANALYSIS OF PLATE AND BEAMS COMPOSITE STRUCTURES

I.IntroductionTheengineeringstructuresareoftells,'1>:'rectcdtotheactionofthestochasticloadingthatvarieswiththetime,forexample,theengineeringstructuresactedonbytheearthquake,theoceanstructuresactedonbydynamicpressure,andthevehiclesofthetransportationinflue…     

外包钢-砼组合梁纯扭作用下抗扭刚度的实验及数值模拟

为了研究新型外包钢-砼T形截面组合梁在纯扭作用下的变形性能，设计了5根不同配箍率的的足尺悬臂组合梁。通过对5根悬臂梁的抗扭性能的实验研究，得到了组合梁的扭矩-扭率关系曲线。利用有限元分析软件ANSYS，对组合梁的抗扭性能进行了非线性有限元分析，得到了混凝土与外包钢在极限阶段的应力云图。根据实验以及有限元结果分析了组合梁在整个加载过程中扭转刚度的变化。基于现行砼结构设计规范，提出了组合梁从开裂到极限阶段抗扭刚度的计算公式，可供组合梁受扭设计参考。把有限元模型和公式的计算结果与实验结果进行比较，三者吻合较好。     

Axial-flexural coupled vibration and buckling of composite beams using sinusoidal shear deformation theory

A finite element model based on sinusoidal shear deformation theory is developed to study vibration and buckling analysis of composite beams with arbitrary lay-ups. This theory satisfies the zero traction boundary conditions on the top and bottom surfaces of beam without using shear correction factors. Besides, it has strong similarity with Euler–Bernoulli beam theory in some aspects such as governing equations, boundary conditions, and stress resultant expressions. By using Hamilton’s principle, governing equations of motion are derived. A displacement-based one-dimensional finite element model is developed to solve the problem. Numerical results for cross-ply and angle-ply composite beams are obtained as special cases and are compared with other solutions available in the literature. A variety of parametric studies are conducted to demonstrate the effect of fiber orientation and modulus ratio on the natural frequencies, critical buckling loads, and load-frequency curves as well as corresponding mode shapes of composite beams.     

Local buckling of wide-flange thin-walled anisotropic composite beams

The present contribution deals with the onset of local buckling of compressively loaded thin-walled beams with open I, C, Z, T and L-cross-sections made of laminated composite materials. The method employs a discrete plate analysis approach in the course of which each structural subelement of interest—which presently is the flange—of the thin-walled cross-section is considered as a separate composite plate with elastic rotational restraints at those edges where an adjacent substructural element is located. While in many investigations the lamination schemes of webs and flanges are considered to be purely orthotropic, in the present paper the laminate layups are allowed to be of an arbitrary non-orthotropic nature, which also allows for the analysis of laminates with inherent bending–torsion coupling. The analysis of the buckling loads of the flanges of thin-walled composite beams is performed using the Ritz-method for which some especially adjusted displacement shape functions are employed. For the case of pure orthotropy, a novel closed-form solution is described. The accuracy of the employed approaches is established by comparison with accompanying finite element simulations of thin-walled composite beams. It is revealed that the presented methodology is highly efficient in terms of computational effort and yet performs with satisfying accuracy, which makes it very attractive for actual practical applications whenever the local stability behaviour of wide-flange thin-walled composite beams is to be considered.     

一种适用于下承式钢桁结合桥计算的板梁组合单元

下承式钢桁结合桥具有建筑高度较低、行车时燥声、震动较小、刚度较大等优点,是高速铁路桥梁中比较理想的结构形式之一。为了能较合理和方便地分析下承式钢桁结合桥的力学行为,本文提出了一种考虑板梁共同作用和相对滑移的板梁组合单元。该单元以矩形板的4个结点的结点位移和板梁结合面3个点的相对滑移作为单元的基本自由度,板的位移模式通过对常规4结点矩形平板壳单元的形函数修正得到,梁的位移模式则根据板和梁之间的变形协调条件来确定。文末的算例表明,本文的解与试验结果和通用工程软件解较为吻合,说明了本文理论和方法的正确性。     

Mechanical behavior of sandwich composite beams made of foams and functionally graded materials

We investigate sandwich composite beams using a direct approach which models slender bodies as deformable curves endowed with a certain microstructure. We derive general formulas for the effective stiffness coefficients of composite elastic beams made of several non-homogeneous materials. A special attention is given to sandwich beams with foam core, which are made of functionally graded or piecewise homogeneous materials. In the case of small deformations, the theoretical predictions are compared with experimental measurements for the three-point bending of sandwich beams, showing a very good agreement. For functionally graded sandwich columns we obtain the analytical solutions of bending, torsion and extension problems and compare them with numerical results computed by the finite element method.     

钢--混凝土组合结构抗震性能研究进展简

钢-混凝土组合结构的抗震性能受到了工程研究领域的广泛关注. 本文总结了国内外研究者在组合梁、组合柱、组合节点及组合框架结构抗震性能方面的试验研究概况,分析了组合构件的作用机理及地震损伤演化累积效应,讨论了钢-混凝土组合结构地震反应分析的数值模型,包括微观模型、宏观模型以及近年来迅速发展的多尺度模型,并阐述了组合结构抗震性能评价指标及抗震性能水平的确立方法.     

High-order layerwise mechanics and finite element for the damped dynamic characteristics of sandwich composite beams

A high-order discrete-layer theory and a finite element are presented for predicting the damping of laminated composite sandwich beams. The new layerwise laminate theory involves quadratic and cubic terms for approximation of the in-plane displacement in each discrete layer, while interlaminar shear stress continuity is imposed through the thickness. Integrated damping mechanics are formulated and both laminate and structural stiffness, mass and damping matrices are formed. A finite element method and a beam element are further developed for predicting the free vibration response, including modal frequencies, modal loss factors and through-thickness mode shapes. Numerical results and evaluations of the present model are shown. Modal frequencies and damping of sandwich composite beams are measured and correlated with predicted values. Finally, parametric studies illustrate the effect of core thickness and face lamination on modal damping and frequency values.