【作者】 罗俊礼；

【导师】 徐志胜；

【作者基本信息】 中南大学 ， 土木工程， 2014， 博士

【摘要】 高速铁路预应力箱梁的收缩徐变变形会影响轨道的平顺性,严重时甚至可能造成扣件破坏,进而威胁行车安全。温度效应产生的结构应力是预应力混凝土梁发生裂纹的主要原因,严重的温度裂缝会损害桥梁耐久性和安全性,特别是对于混凝土箱形梁,温度荷载起控制作用。收缩徐变和温度效应都是随时间变化的,作用机理比较复杂,影响因素也很多,并且还存在相互耦合作用。为满足高速铁路长期运营使用对安全性和轨道高平顺性的要求,对无砟轨道预应力混凝土简支箱梁的收缩徐变、温度等时变效应进行分析研究是非常必要的。本文以沪杭客运专线桐乡梁场的制梁工程为依托,对高速铁路32m预应力混凝土箱梁的收缩徐变效应和温度效应展开一系列的现场测试、理论研究和模拟仿真分析。全文主要工作概括如下：(1)基于ACI209(1992)收缩徐变预测模型,通过修正钢筋约束影响系数、强度影响系数、塌落度影响系数,提出了具有一定精度的适用于高性能混凝土预应力箱梁的收缩徐变预测模型。(2)通过试验综合比选,推荐了适用于不同环境条件的客运专线箱梁的养护制度,对于3种环境温度水平给出相应的自然养护方法。研究了不同养护制度下箱梁早期温度场、温度应力的分布规律以及对后期徐变变形的影响。(3)通过对沪杭客运专线的一批二期恒载加载时间为60d、90d、120d的预应力混凝土箱梁的收缩徐变变形进行测试,得出结论二期恒载加载时间对箱梁徐变上拱有显著影响,混凝土龄期60～120d都是比较合理的加载时间。(4)基于湿度、温度、理论厚度三个因素相互独立的假定,建立了0～90℃范围内,温度与徐变的耦合作用模型。并将该模型与有限元软件相结合,较好地模拟了水化热和季节温度荷载作用下,预应力混凝土箱梁的内力和变形。(5)通过相似模型试验的方法,比较研究了预应力张拉批次、张拉时间、预应力筋数量和控制应力对客运专线预应力箱梁徐变的影响规律。两次张拉成型工艺较一次张拉成型工艺的更为合理；适当降低张拉控制应力可以有效减小后期变形和结构内力；延后终张拉时间至28d龄期,对于预应力梁长期变形的控制有积极作用。更多还原

【Abstract】 The shrinkage and creep deformation of PC bridge can affect the smoothness of rail track, and even cause serious damage to fasteners, which may result in serious threat to traffic safety. The temperature effect is the main reason of cracking in the PC beam. The temperature cracks will damage the durability and safety of bridge, especially the concrete box girder. Shrinkage, creep and temperature effects are all time-depended, and also have mutual coupling effect.A series of tests, theoretical study and simulation analysis on the effects of the shrinkage, creep and temperature on32m PC box girder were conducted, on basis of beam production process in Tongxiang Beam Plant of Shanghai Hangzhou passenger dedicated line. The main work of the paper is summarized as follows:(1) Based on the creep and shrinkage prediction model of ACI209(1992), the creep and shrinkage prediction model for high performance concrete in passenger dedicated railway bridges was appropriately proposed by introducing the influence coefficients of reinforced constraint, concrete strength and slump of fresh concrete.(2) An economic curing system for box girder of passenger dedicated line was presented applicably to different environmental conditions, depended on comparative experimental study. Natural curing methods corresponding to three different temperature levels were given out. The distribution of the temperature field and thermal stress in box-girder bridge in early age was studied under different curing methods. (3) Tests on shrinkage and creep deformation of box girders in Shanghai-Hangzhou passenger dedicated line was carried out. The results showed that the loading-age of secondary dead load had a significant influence on creep camber of box girder, and the age of60d-120d seemed to be a reasonable loading time.(4) A coupling model of temperature and creep in the range of0℃-90℃was established, on the assumption that humidity, temperature and thickness were three independent factors. The model combined with the finite element software, is applied to simulate the internal force and deformation of prestressed concrete box beam under the temperature loads.(5) The creep camber of PC box girder is seriously affected by prestressed tension program:such as tension batch, tension time, quantity of prestressed tendons and the controlled stress, according to a similarity model test carried in this paper. Prestressed tension divided into two batches was more properly than completed in a one-time. It does make sense to delay the final tension time to28d age, in controlling the long-term deformation of PC beam.更多还原