矮塔斜拉桥拉索和预应力筋的相互影响及配置优化研究

发布时间：2018-06-04 04:41

本文选题：矮塔斜拉桥 + 索筋相互影响　；参考：《长安大学》2015年硕士论文

【摘要】：矮塔斜拉桥的拉索和主梁预应力筋之间存在着相互影响的作用,该作用表现为施工中相互影响和成桥相互影响两个方面。施工中斜拉索的张拉必然会影响已经张拉锚固的预应力筋的应力储存值,预应力筋的张拉也同样会影响已经锚固的拉索索力值,这两者之间的相互影响对桥梁的施工过程分析和控制有着举足轻重的意义。成桥时拉索和主梁共同承担活荷载,但各自承担的比例实际中不同的设计者依据自己的设计经验会有不同的结果,虽然结构都能运营使用,但设计是否合理经济仍是遗留问题。本文以某一实际工程为背景,借助有限元软件MIDAS CIVIL围绕以上两个问题展开研究。首先通过分级改变斜拉索和主梁预应力筋的张拉力值,总结结构的挠度、内力和应力随之变化的规律,分析索力和预应力各自对结构的影响情况。其次在有限元软件中通过将施工阶段细化,分别研究悬臂浇筑、边跨合拢和中跨合拢三个阶段拉索和主梁预应力在张拉时相互之间的影响,得到不同阶段不同部位的索筋张拉对其他的索筋产生的影响。最后以索筋总造价为目标函数,以索梁各自承担的活荷载比率作为二者配置量的表征,对拉索和主梁预应力筋的配置量进行优化,使得拉索和预应力筋的总费用最少。经过研究,矮塔斜拉桥拉索对结构挠度影响的敏感性约为主梁预应力的2倍;对结构内力的影响拉索约为主梁预应力敏感度的2倍;对结构应力的影响拉索约为主梁预应力敏感度的1.48倍;悬臂施工阶段预应力筋的张拉会使得全桥拉索索力减小,而且离张拉位置越近拉索的卸载程度越大,到最大悬臂时拉索的最大卸载量约为6.7%;边跨合拢预应力张拉时边跨拉索的最大卸载量约为2.7%,中跨拉索受影响比较小;中跨合拢预应力张拉时中跨拉索的最大卸载量约为6.4%,边跨拉索受影响比较小;斜拉索张拉时短束的预应力损失值比长束大,顶板束比底板束大,最大的预应力损失量约为3.3%;最后将原设计方案中的索筋配置比例0.209优化为0.263时,使得在不改变结构性能的前提下索筋总造价最经济。
[Abstract]:There is interaction between cables and prestressed tendons of the main girder of the cable-stayed bridge with low tower, which is shown by the interaction between the construction and the bridge. In construction, the tension of the cable will inevitably affect the stress storage value of the pre-stressed tendons which have already been tensioned and Anchorage, and the tensioning of the prestressed tendons will also affect the values of the cable forces already anchored. The interaction between the two plays an important role in bridge construction process analysis and control. When the bridge is completed, the cable and the main beam bear the live load together, but in practice different designers will have different results according to their own design experience. Although the structure can be operated and used, whether the design is reasonable or economical is still a question left over. Based on a practical project, this paper studies the above two problems with the help of finite element software MIDAS CIVIL. Firstly, by changing the tensioning force of the cable and the prestressed tendons of the main beam, the law of the deflection, internal force and stress of the structure is summarized, and the influence of the cable force and the prestress on the structure is analyzed. Secondly, in the finite element software, the influence of cable and main beam prestress in the three stages of cantilever pouring, side span closing and middle span closing is studied by refining the construction stage. The effects of different parts of cable tension on other tendons are obtained. Finally, the total cost of cable and girder is taken as the objective function, and the ratio of live load borne by cable and beam is taken as the representation of the configuration of the two. The configuration of cable and prestressed tendons is optimized to make the total cost of cable and prestressed tendons the least. The sensitivity of cable to structural deflection is about 2 times as much as that of main beam, and the influence of structural internal force is about 2 times of that of prestressed beam of cable stayed bridge with low tower. The prestressing sensitivity of the main beam is 1.48 times that of the cantilever construction, and the tension of the prestressed tendons in the cantilever construction stage will reduce the cable force of the whole bridge, and the more close to the tension position, the greater the unloading degree of the cable. The maximum unloading amount of the cable is about 6.7when the cantilever is maximum, the maximum unloading quantity of the cable is about 2.7when the side span is closed prestressing tensioning, and the influence of the mid-span cable is relatively small. The maximum unloading amount of the mid-span cable is about 6.4, and the influence of the side span cable is relatively small, the loss of prestressing force of the short cable is larger than that of the long beam, and the roof beam is bigger than the bottom beam. The maximum loss of prestress is about 3. 3. Finally, the proportion of cable and steel bars in the original design is optimized to be 0. 263, which makes the total cost of cables and tendons the most economical without changing the performance of the structure.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U448.27

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