徐变对不同施工方法建造连续梁桥内力演变的影响分析

发布时间：2018-05-10 14:13

本文选题：预应力混凝土连续梁桥 + 徐变　；参考：《北京交通大学》2017年硕士论文

【摘要】：预应力混凝土连续梁桥是当今桥梁中应用最为广泛的桥型之一,其适应跨径可以从10-40m的中小跨径直到200-300m的超大跨径。目前连续梁桥的施工方法主要有满堂支架现浇法、简支变连续施工法、悬臂施工法以及顶推施工法等。已有研究表明,不同的施工方法建造的连续梁桥成桥后的恒载内力不同。其中满堂支架现浇法和顶推施工法建造的连续梁桥恒载内力与一次成形结构的内力相同,而简支变连续施工法建造的连续梁桥恒载内力与简支梁桥结构内力分布相似,悬臂施工法建造的连续梁桥恒载内力与悬臂梁的恒载内力分布相近。由于不同施工方法在混凝土连续梁中产生不同的内力状态,进而影响到徐变的发展,对于这一问题的研究尚不充分,从而导致在混凝土连续梁的长期性能分析缺乏必要的认识,影响既有桥梁评估的正确性。因此,本文将对不同施工方法建造的预应力混凝土连续梁桥的徐变效应进行研究,探讨其基本规律。全文主要的研究内容如下:采用有限元法,分别对满堂支架施工法、简支变连续施工法和悬臂浇筑法建造的连续梁桥成桥后恒载内力的分布以及演变趋势进行分析,包括考虑结构布置有预应力钢束和不考虑预应力钢束两种情况,并进行对比。分析混凝土徐变对这三种施工方法建造的连续梁桥恒载内力的长期影响,并选取了主梁典型截面进行具体分析。在简支变连续施工法建造的连续梁恒载内力演变分析中除了采用有限元法,还采用了狄辛格法理论计算主梁典型截面的恒载内力,并与有限元法得出的结论进行比较,结果表明这两种方法得出的结论是一致的。对于悬臂浇筑法建造的连续梁桥,运用无应力状态法分析施工过程对结构内力的影响;在进行全桥内力演变分析前,将实测的应变值与有限元法的计算值进行对比,验证了模型的可靠性。研究表明,布置有预应力钢束的连续梁,结构的恒载内力随时间的增长变化相对较小。而对于没有考虑预应力钢束作用的结构,若采用满堂支架施工法施工,结构的恒载内力随时间的增长变化很小;若采用简支变连续或者悬臂浇筑法施工,结构的恒载内力分布随着时间的增长趋向于一次成形结构的恒载内力。从简支变连续施工法和悬臂施工法建造连续梁桥徐变次内力的分析中可以看到,预应力钢束的存在对连续梁桥混凝土徐变次内力有协调作用,制约了其发展。
[Abstract]:Prestressed concrete continuous beam bridge is one of the most widely used bridges. Its adaptive span can range from 10-40m to 200-300m. At present, the construction methods of continuous beam bridge include cast-in-situ method, simple support and continuous construction method, cantilever construction method and pushing construction method. Studies have shown that the dead load internal forces of the continuous beam bridges constructed by different construction methods are different. The internal force of dead load of continuous beam bridge constructed by cast-in-place method and pushing construction method is the same as that of primary forming structure, but the distribution of internal force of continuous beam bridge constructed by simply supported variable continuous construction method is similar to that of simply supported beam bridge structure. The distribution of dead load internal force of continuous beam bridge constructed by cantilever construction method is similar to that of cantilever beam. Because different construction methods produce different internal force state in concrete continuous beam, and then affect the development of creep, the research on this problem is not enough, which leads to the lack of necessary understanding on the long-term performance analysis of concrete continuous beam. Affects the correctness of the existing bridge assessment. Therefore, the creep effect of prestressed concrete continuous beam bridge constructed by different construction methods is studied in this paper, and its basic law is discussed. The main contents of this paper are as follows: the distribution and evolution trend of dead load internal force of continuous beam bridge constructed by full support construction method, simple support variable continuous construction method and cantilever pouring method are analyzed respectively by using finite element method. Including the consideration of the structural layout of prestressed steel bars and do not consider the prestressed steel bundles two cases, and compared. This paper analyzes the long-term influence of concrete creep on the dead load internal force of the continuous beam bridge constructed by these three construction methods, and selects the typical section of the main beam to carry on the concrete analysis. In the analysis of the evolution of the constant load internal force of the continuous beam constructed by simply supported variable continuous construction method, in addition to the finite element method, the theory of Deisinger's method is used to calculate the dead load internal force of the typical section of the main beam, and the conclusion obtained by the finite element method is compared with that obtained by the finite element method. The results show that the conclusions of the two methods are consistent. For the continuous beam bridge constructed by cantilever pouring method, the influence of the construction process on the internal force of the structure is analyzed by using the stress-free state method, and the measured strain value is compared with the calculated value of the finite element method before the analysis of the evolution of the internal force of the whole bridge. The reliability of the model is verified. The results show that the dead load internal force of the continuous beam with prestressed steel beam is relatively small with the increase of time. However, for structures that do not consider the role of prestressed steel bundles, the dead load internal forces of the structures will change little with time if the construction method of full support is adopted, and if the simple support is changed continuously or the cantilever pouring method is used, The distribution of the dead load internal force of the structure tends to the dead load internal force of the primary forming structure with the increase of time. From the analysis of the secondary internal force of creep of continuous beam bridge constructed by simply supported continuous construction and cantilever construction, it can be seen that the existence of prestressed steel bundle can coordinate the creep secondary internal force of concrete of continuous beam bridge, which restricts its development.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U445.4

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