【作者】 唐春霞；

【导师】 吴迅；

【作者基本信息】 同济大学 ， 桥梁与隧道工程， 2006， 硕士

【摘要】 针对目前大跨度预应力混凝土桥梁普遍出现裂缝的问题，本文以广东省磨刀门大桥为工程背景，研究了影响大跨度预应力混凝土连续箱形梁桥抗裂性能的主要因素。主要研究内容体现在以下几个方面：(1)通过大量文献资料的调研，提出了对大跨度预应力混凝土连续箱形梁桥的抗裂性分析关键在于结构的空间应力状态的观点，要对结构进行基于空间应力状态的抗裂性分析，特别是结构局部空间应力状态的分析。(2)对结构进行空间整体抗裂性能分析，分别计算了永久荷载(恒载、预应力)+各单项因素(收缩徐变、温度影响力、变位影响力及活载)作用下结构的应力响应，指出了采用平面杆系计算软件的设计方法在分析箱梁空间应力方面存在的不足，得出了对结构空间受力影响最大的因素为预应力效应、其次为局部温差效应的结论。(3)针对整体空间抗裂性分析中发现的中跨跨中合龙段底板抗裂性能不能满足的问题，进行了局部的抗裂性分析，通过计算分析发现了底板纵向预应力筋配束不合理是导致底板主拉应力值超限的主要原因。并通过比较研究提出了优化结构受力的建议方案。根据本文的计算分析，可知对大跨度预应力混凝土箱梁桥进行基于空间应力状态的抗裂性分析是很有必要的。通过结构局部空间应力分析，在大跨度预应力混凝土箱梁桥的设计中对底板预应力配置、底板线形以及底板防崩钢筋进行更为合理的设计，能更好的避免底板开裂现象的发生。更多还原

【Abstract】 Aiming at the crack phenomena in long-span prestressed concrete continuous box girder bridges at present, on the background of Modaomen Bridge in Guangdong province, the main factors effectting the capability against cracking for long-span PC box girder bridges are studied and discussed in this thesis. The main contents are described as follows:(1) Through looking over lots of literatures, the standpoint is brought forward in this thesis that the key on analysis of the capability against cracking for long-span PC box girder bridges is three-dimensional stress. It is necessary to study on the analysis of the capability against cracking based on three-dimensional stress, especially on the local analysis.(2) In the three-dimensional finite analysis of the whole model, the stress response of the structure under the permanent load (dead load + prestressing force) add each single factor (shrinkage, creep, temperature difference, foundation displacement and live load) is analysed, and the shortage of the plane software is pointed out, the conclusion is made that prestressed reinforcement is the most important factor and local temperature difference takes the second place.(3) Aiming at the deficiency of capability against cracking in bottom deck of span center in midspan, the local analysis is applied. And the conclusion is considered to be that overlarge prestressing reinforcement in bottom deck is the main factor resulting in the ultralimit of principal tensile stress .The optimization case is proposed.According to the calculation and analysis in the whole thesis, it is necessary to analyse the capability against cracking based on three-dimensional stress. And through the local analysis , the more reasonable design precepts of the prestressing force , line shape and reinforcing steel against break-up in the bottom deck of long-span PC box girder bridges can be obtained, then the crack development of the bottom deck can be avoided.更多还原