【作者】 赵长军；

【导师】 徐兴；

【作者基本信息】 浙江大学 ， 结构工程， 2002， 博士

【摘要】 大跨度桥梁的研究，是当前桥梁学科中最重要与最活跃的领域之一。本文针对当前大跨度桥梁的研究背景，提出了一种新型的桥梁结构体系一大跨索桁桥。上缆、下缆通过锚碇和吊索张拉成拉索桁架，两片桁架支撑着刚度较小的箱梁和桥面系，构成了大跨索桁桥。该桥型一方面利用缆索的抗拉性能；另一方面利用桁架结构刚度大的优点。这种新的桥梁结构体系把这二者的优势充分结合起来。 对大跨索桁桥进行了全桥静力和动力优化研究，初步得出各个部分的合理的构造尺寸和初始应力状态。建立有约束的非线性优化数学模型，全面考虑影响全桥静力和动力性能的各种参数，以全桥造价最低为目标，以成桥状态的位移、应力和动力特性为约束条件，进行优化分析方法研究。以江阴大桥为比较对象，优化结果显示大跨索桁桥材料用量与江阴大桥基本持平，但静、动力性能显著改善。 在研究过程中，开发了适用于大跨索桁桥的研究理论和计算方法。推导了适合缆索承重桥梁的缆索单元；引入虚拟单元理论，提出适用于大跨缆索承重桥梁钢箱梁的一种新方法—虚拟层合板单元法，该单元具有计算效率高，可以模拟复杂结构并满足工程需要等诸多优越性。结合大位移理论、缆索单元和虚拟层合板单元，形成一套适用于大跨索桁桥的计算方法。 总结静力和动力优化的结果，提出了大跨索桁桥的合理的结构尺寸。探讨了当今世界各国荷载规范的发展状况和大跨索桁桥最不利的荷载组合情况。在全桥整体分析中，对索桁架结构、桥塔和加劲梁在各种最不利荷载组合的情况进行了详细分析，并提出了锚碇的初步设计方案。通过翔实的静力研究证明了大跨索桁桥是一种材料节省，静力刚度大，具有良好的经济指标和使用性能的新桥型。 提出了大跨度缆索承重桥梁整体动力分析的一种新方法：完全计入缆索的大位移、初应力等的影响；钢箱梁的模拟做到了高精度与高效率的和谐统一，单元数量与目前常用的脊梁法相近，但单元的刚度和质量分布与真实结构相同，并且可以自动生成。本文大跨索桁桥动力特性与江阴大桥相比主要有以下特点：各个振型出现的次序发生变化；对称和反对称扭转基频有了大幅度的提高；各个振型的耦合现象更为突出。在动力特性分析的基础上进行了地震响应研究，通过反应谱和动力时程两种方法的对比，可以得出这样的结论：地震对大跨索桁桥的影响并不显著，其设计受静力控制。最后对该种桥型的空气动力稳定性进行了评估。证明大跨索桁桥是一种抗风性能优良的新桥型。更多还原

【Abstract】 A new type bridge named long-span cable-truss bridge(LSCTB) was created which can combines advantage of cable and truss structure. The bridge researched in this paper has same length and width as Jiangyin Bridge.Static and dynamic optimum analysis were done using first-order method. Nonlinear mathematics model with constraints was made. The minimum global cost of bridge was selected as goal function,Design variables were selected as much as possible in order to find out the main factors affecting characteristics of LSCTB,Displacements,structure stress and dynamic characteristics were used as constraint variables. Conclusion was drawn that static and dynamic characteristics were improved greatly comparing to Jiangyin Bridge.A new kind of theory and calculating method which is suitable to cable supported bridges was developed in this paper. Cable element can include the structure’s geometry nonlinearity and initial stress,Virtual laminated element has high calculating efficiency and good precision.Dimensions of LSCTB was put forward based on conclusions of optimum analysis. Development of load code and controlling load condition were discussed,Detailed analysis of cable-truss,bridge tower,stiffening girder and anchorage was done which proved that LSCTB is a competing bridge type.How to model stiffening box-girder is a difficult problem for a long time,Virtual laminated plate element method which put forward in this paper is a powerful tool to solve the problem. This method has high efficiency and precision comparing to traditional method. Dynamic analysis of this bridge showed that the bridge’s seismic response was small and flutter critical wind speed was improved to a high level.更多还原