节点文献
大宽跨比正交异性板鱼腹式多室薄壁箱梁结构受力性能和试验研究
【作者】 张慧；
【导师】 杨子江；
【作者基本信息】 兰州交通大学 ， 桥梁与隧道工程， 2012， 博士
【摘要】 本文以某跨线桥的实际工程——大宽跨比正交异性板鱼腹式薄壁钢箱梁为研究对象，在总结国内外研究成果的基础上，通过大比例模型试验与三维精细化有限元分析，系统地研究了该结构的力学性能，探讨了在分析此类结构不同问题时与之相适应的简化分析计算方法。论文的主要工作如下：首次进行了大宽跨比正交异性板鱼腹式薄壁箱梁桥的大比例有机玻璃模型试验研究，系统测试了结构的整体力学性能；通过试验结果和两种有限元模型计算值的对比分析，揭示了此类复杂结构的整体力学性能。比较了腹板和横隔板间顶板和底板应力分布状态，得到了该结构控制截面的正应力分布规律。为此类结构在工程上的推广应用提供了参考依据。基于最小势能原理，假定剪力滞翘曲函数为余弦函数模式，利用能量变分原理，推导出单箱多室（奇数）薄壁箱梁剪力滞控制微分方程和边界条件，并给出了微分方程的解析表达式；结合大比例有机玻璃模型，建立了全桥精细化三维有限元模型，通过数值分析、解析解与模型试验，对比分析了单箱五室两跨连续箱梁结构的顶底板的剪力滞系数的分布规律，并首次研究了斜曲边腹板对多室箱梁剪滞效应的贡献。以薄板的平面应力问题和薄板弯曲问题为对象，将带有纵向加劲肋的薄壁箱梁结构正交异性板换算为等厚度材料正交异性板，选取四节点矩形单元，构造出一种新的考虑材料正交异性的四节点位移形有限元列式，通过算例验证了计算方法的可靠性，本文计算方法可方便地纳入位移法通用有限元程序系统中。从钢箱梁与铺装结构一体化的角度出发，展开钢箱梁与铺装层相互作用的局部力学性能分析。以最不利工况为基础，讨论通过改变影响桥面铺装结构性能的参数：钢桥面板厚度、钢纤维混凝土铺装层厚度、沥青混凝土铺装层厚度及钢桥面顶板加劲肋密度等，通过精细化局部三维有限元数值模型，分析了钢桥面板和钢纤维混凝土铺装层的变形、应力（应变）随各参数变化的规律。给出了各参数的合理取值界限。基于梁格法的优化理论，以结构的单位长度用钢量为目标函数。把横隔板间距、横隔板厚度、横隔板高度、加劲肋高度、加劲肋厚度、加劲肋数量和桥面板厚度等七个参数作为优化设计变量。以结构的变形和容许应力限值作为主要约束条件，研究了以目标函数为标准的参数优化设计取值。
【Abstract】 A new type of streamlined girder (lenticular cross section) bridge with thin-walled steelbox girder is proposed in this paper. The main characteristics of this bridge are thin-walled,multi-cell, with large width-span ratio and that use orthotropic top/bottom/longitudinal-diaphragm plates. The aim of this study is to investigate the effect of the wholebehavior in thin-walled box girder bridges with large width-to-span ratios through bothexperimental and numerical studies. In the same time, several sifferent simple analysismethord are discussed. The main work in this paper is as follow:A large-scale Plexiglas model is tested under different loading cases. The materialparameters are obtained from physical characteristics tests and tensile tests. The deflectionsand strains in each control section are tested. It is the first time to test this whole bridge modelof streamlined girder (lenticular cross section) bridge with thin-walled steel box girder.Inaddition, two different stimulation models were introduced. It is illustrated that the propertiesof this class of bridges. The stress distribution in top plate and bottom plate between adjacentwebs and diaphragms are compared. It is a good reference to the future application of thistype of structure.One theritical methord is presented to analysis the shear lag effection in this bridge. Basedon principle of minimum potential energy, a cosine function is defined as warping function.Then, a control differential eguation are induced by variation method. Finally, the stress anddeflection general formulas of a two spans continous mutil-cell box girder are given. Basedon the testing, shear lag of top plate and bottom plate in a two spans continous five-cell boxgirder are analyzed. It is the first time to study the contribution of streamlined web to thewhole structure in shear lag.The steel plate is considered as a shell, thus the analysis can be separated into two parts:one is the problem of the plane stress, the other is the theory of the thin slab bending. Thestructure with continuous longitudinal stiffened box girder bridge is converted to ananisotropy material plate with uniform thickness. A new finite element determinant is builtand programmed. Based on the continuous longitudinal stiffened box girder bridge, thecomparative analysis among fined finite element model, experiment model and thecomputational method in this study has been investigated. The results show that thecomputational method in this study can meet the engineering requirements and save too muchtime in modeling and post processing.In order to adjust the stiffness ratio of the traditional orthotropic bridge deck as well as thepavement overlay. In this paper, an orthotropic steel bridge deck stiffened with the pavementoverlay is analyzed. The pavement consists of the cement-based and asphalt-based overlays. Several parameters are choosen to analysis the structural mechanics utilizing thefinite-element method. Then, the porper range of each parameter is given.Optimal design is seek to satisfy all performance requirements as well as to minimize thecost of construction. With high-speed computers, finite element methods, and efficientoptimization algorithms, structural optimization techniques have expanded for the design ofadvanced and complex structures. Based on the the grillage method in optimal design, thesteel consumption is choosen as the object function. There are seven parameters, such as thedistance between adjacent diapgragms, the thickness and height of diapgragm and stiffeningrib, the number of the stiffening rib and the thickness of the top plate. The constraintconditions are the deflection and allowable stress. The final values of the optimal parametersare given.