大吨位T构转体桥承台抗裂性分析

发布时间：2018-04-13 08:15

本文选题：转体施工 + 大体积混凝土承台　；参考：《武汉理工大学》2014年硕士论文

【摘要】：随着我国桥梁建设事业的不断发展，大跨径大吨位的桥梁越来越多的采用转体施工。桥梁转体施工工艺，在建造过程中本着“转得动、转得稳、转得准”的原则，对转动体系的施工与监控尤为重要。大吨位转体桥梁不仅要求施工精良的转动体系，而且要求体积大、强度高、稳定性好的混凝土承台。本文以京包铁路分离式立交桥转体施工控制和稳定性分析项目为工程背景，选用ANSYS分析软件对大吨位T构转体桥承台进行了抗裂性能分析。主要内容有： (1)分析了大体积混凝土结构早期开裂的主要原因，是水泥水化放热致使混凝土结构内部产生不均匀拉应力引起的。从而通过对大体积混凝土承台浇筑后前十天的养护环境模拟，对大体积混凝土承台进行了温度场和温度应力场分析，并通过分析的结果与实测结果对比，验证了分析方法的可行性。 (2)对比了大体积承台的两种主要设计方法：控制截面法和空间桁架模型分析法，对转体桥承台施工过程中和转体就位封装后，承台的有效高度发生变化，根据承台矩厚比，分别对承台进行了承载能力分析，并对承台内关键受力部位进行了精细化分析。 (3)通过对京包铁路分离式立交桥转体施工过程的分析，确定了针对承台的三个典型工况：称重试验前，配重后，封装后，分别对承台进行分析计算，得出了承台的传力模式和破坏机理。 (4)按照现场随机振动实测数据，近似转化成随机荷载施加在承台上，，分析了承台关键受力部位在随机荷载作用下的响应。验证了转体桥承台内钢转盘应力并非圆心处最大，而是延半径方向距圆心2/3R处最大。 (5)参照规范要求，结合现场实测数据，对大体积承台的温度抗裂措施提出了建议。并通过分析转体桥承台在巨大竖向荷载作用下的传力模型和破坏机理，提出了转体桥承台在荷载作用下的抗裂建议。研究表明：导致大吨位T型刚构转体桥承台开裂的因素主要有温度应力引起的开裂，和不平衡荷载以及随机荷载作用下的开裂。根据京包铁路分离式立交桥转体桥施工过程分析，证明了称重试验前承台内的应力状态为最危险状态。对包含转动体系的大体积承台的抗裂性能分析结果提出温度裂缝以及荷载裂缝的预防措施，对大吨位转体桥施工特别是承台的施工提供保障。
[Abstract]:With the continuous development of bridge construction in our country, more and more bridges with long span and large tonnage are constructed with rotary construction.In the process of construction, it is very important for the construction and monitoring of the rotational system to follow the principle of "turning can move, turning steadily and turning accurately".The large tonnage rotary bridge requires not only a well-constructed rotating system, but also a concrete cap with large volume, high strength and good stability.In this paper, based on the construction control and stability analysis project of separated interchange bridge of Beijing-Baotong railway, the anti-crack performance of large-tonnage T-structure rotary bridge cap is analyzed by using ANSYS analysis software.The main contents are:1) the main causes of early cracking of mass concrete structures are analyzed, which are caused by uneven tensile stress in concrete structures caused by hydration and heat release of cement.The temperature field and temperature stress field of mass concrete cap are analyzed by simulating the maintenance environment ten days before pouring, and the results are compared with the measured results.The feasibility of the analytical method is verified.This paper compares two main design methods of mass cap: control section method and spatial truss model analysis method. The effective height of the cap changes during the construction process of the cap of the rotary bridge and after the turning-in package, according to the ratio of the cap moment to the thickness,The bearing capacity of the cap is analyzed, and the key parts of the cap are analyzed in detail.Through the analysis of the construction process of the separated interchange bridge of Jingbao railway, three typical working conditions are determined: before weighing test, after weighing, and after encapsulation, the pile cap is analyzed and calculated separately.The transmission mode and failure mechanism of cap are obtained.4) according to the measured data of random vibration in the field, the response of the key part of the cap subjected to random load is analyzed.It is verified that the stress of the steel turntable in the cap of the rotary bridge is not the largest at the center of the circle, but the maximum at the direction of the extension radius being 2 / 3R from the center of the circle.5) according to the requirements of the specification and the field measured data, some suggestions are put forward for the temperature crack resistance measures of the mass cap.Based on the analysis of the load transfer model and failure mechanism of the turning-bridge cap under the huge vertical load, the paper puts forward the anti-crack suggestion of the turning-bridge cap under the load.The results show that the main factors leading to the cap cracking of the large-tonnage T-type rigid frame rotary bridge are the cracking caused by temperature stress, the unbalance load and the cracking under random load.According to the analysis of the construction process of the rotary bridge of the separated interchange bridge of the Beijing-Bao-Baotong Railway, it is proved that the stress state in the cap before weighing test is the most dangerous state.Based on the analysis of crack resistance of large cap with rotating system, the preventive measures of temperature crack and load crack are put forward, which can provide guarantee for the construction of large tonnage rotary bridge, especially for the construction of pile cap.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U443.25

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