【作者】 何为；

【导师】 徐兴； 项贻强；

【作者基本信息】 浙江大学 ， 结构工程， 2006， 博士

【摘要】 近10年来我国的大跨径悬索桥建设飞速发展。随着悬索桥跨径的不断增大,为保证竣工后桥梁的受力和线型尽量与设计理想状态一致,施工过程中的监控工作显得越来越重要。我国在大跨径悬索桥施工监控方面的研究还处在起步阶段,亟待补充和完善。本文以宜昌长江公路大桥的施工过程为背景,对大跨径悬索桥施工监控中的若干问题进行了研究分析。 以虚拟层合理论为基础建立了悬索桥施工阶段的三维有限元计算模型。在对钢箱梁吊装阶段的计算过程中,利用虚拟层合单元的优点,实现一次性建立全桥模型,然后通过材料参数的适当选取及模型的细部修正,达到对钢箱梁各吊装阶段的模拟。 对钢箱梁吊装阶段的主缆、钢箱梁几何线形、索塔应力、主索鞍顶推量、顶推时机等进行了分析。首次提出大跨径悬索桥主梁吊装过程中塔顶主索鞍的顶推应遵循“小步快跑”原则,即适当增加顶推次数,减小每次顶推的顶推量。根据小步快跑原则制订的顶推方案与实际施工顶推方案及另一种假想的顶推方案的对比计算结果表明,小步快跑方案可使施工过程中的桥塔应力更加逼近理想受力状态,有利于增加桥塔施工安全裕度及全桥结构安全。 结合大量现场试验,提出了符合工程实际的日照温差下带人行道翼缘的扁平钢箱梁温度梯度模式和竖向及横向的温度梯度曲线公式,其顶底板日照温差可达30℃。这对我国现行桥涵设计规范中温度梯度曲线等相关内容是个补充。同时,以钢箱梁节段为研究对象,分别采用中国公路桥涵规范、英国BS5400规范中的温度梯度与本文温度梯度进行了对比计算。说明本文提出的温度梯度模式更符合扁平钢箱梁的实际情况。 对日照温差下钢箱梁的温度应力进行了分析研究。发现在顶底板温差30℃时,钢箱梁顶板温度应力普遍达到100MPa以上,局部可达135MPa(Q345-94钢材屈服强度345MPa)。可见温度应力有可能控制钢箱梁设计(不计锚箱部分),必须给予重视。对钢箱梁节段模型温度应力分析的边界条件确定问题,本文通过严格边界条件和固端边界条件的对比计算后认为,在分析大跨径悬索桥钢箱梁节段的温度应力时,可将全桥主梁视为近似无限长结构,取出一个节段做为研究对象,边界条件可以取为两端固结。其计算结果将与严格真实边界条件下的计算结果相差无几。 以虚拟层合单元为基础建立全桥三维有限元模型,对宜昌桥荷载试验中的静载试验各工况下桥梁结构的响应进行了空间分析计算,结果与实测结果符合较好。说明模型正确。 以解析法为基础分析了悬索桥主缆架设阶段施工监控中主缆无应力长度、基准索股线形更多还原

【Abstract】 While span of suspension bridge is increased, the construction control is more and more important to make the structure stress and geometric shape close to design state. Taking the Yichang Changjiang highway bridge as an example, analysis of construction control of suspension bridge is completed.Based on virtual lamina element theory, a 3D finite element model of suspension bridge in construction period is build up for construction control analysis. Due to advantage of virtual lamina element theory, by adjusting properties of element materials, the finite element model can be simply modified to simulate the steel box beam lifting construction period.Analysis of tower stress and geometric shape of structure during steel box beam lifting construction period is completed. The frequent short steps saddle pushing principle is presented, it means saddle pushing is frequent and space of each pushing is short. Contrastively calculating result shows that frequent short steps saddle pushing scheme makes tower stress more close to perfect state and it is beneficial to safety of structure.Based on field measuring, a temperature field and temperature gradient curve of steel flat box beam are presented. In this temperature gradient curve, the sunshine temperature difference between roof and floor is high to 30℃. Contrastively calculating of temperature stress in steel box beam shows that this temperature field is more close to the actual situation.In the case of sunshine temperature difference between roof and floor is 30℃, the temperature stress in roof of steel box beam is high to 100MPa, even 135MPa (the yield strength of Q345-94 steel is 345MPa). It means that temperature stress maybe vital factor in steel box beam design. In temperature analysis of steel box beam segment, the boundary condition definition is important. Contrastively calculating between actual boundary condition and fixed end boundary condition shows that their calculating results are very close. Therefore, in temperature stress analysis of steel box beam of long span suspension bridge, the whole box beams can be deem as an approximate infinitely long beam, then take out one box beam segment as a subject with the fixed end boundary condition, the calculating result will be close to the actual situation.For study of static load test of Yichang Changjiang highway bridge, a 3D virtual lamina element model of suspension bridge is build up. Theoretical calculation result accord with measure value.Based on analytic method, several controls parameter such as non-stress length of cable and datum strand shape in main cable erection period are analysed. The elevation of strand is changed in main cable erection period. So the elevation of datum strand in cable finished stage is different with that in main cable erection stage. Subsection linear function is used in temperature field of strand. The effect to strand shape caused by temperature is analysed.A method of length amending of straddle suspender cable in main cable clip is presented. Analytic expressions was offered to calculate the tangent point and its corresponding angle. Series expansion and numerical integral method were also investigated to calculate the accurate length of ellipse arc. Analysis results show that the method have high precision and rapidity of convergence.更多还原