多跨矮塔斜拉桥长期受力性能研究

发布时间：2019-01-24 16:48

【摘要】：对混凝土斜拉桥而言,混凝土自身作为一种时效材料,其收缩徐变特性对结构的长期变形有着举足轻重的影响,并且对不同结构形式、不同运营时期收缩徐变对桥梁的受力性能的影响也不尽相同,故有必要研究运营期收缩徐变对桥梁的影响;同时,在建立初始有限元模型时,由于实际建模的需要对实际情况进行了各种简化和假定,依据设计图纸建立的初始有限元模型计算得到的静动力响应与实测值往往有不同程度的差异,因此,如何通过对初始有限元模型的修正从而使修正后的模型的计算值更加接近实测值是一个值得研究的方向。针对以上两点,本文以八里湖大桥为背景,做了以下工作:(1)采用不同的收缩徐变预测模型对八里湖大桥进行理论计算分析,分别计算成桥后收缩徐变对八里湖大桥主梁挠度、斜拉索索力和塔顶偏位的改变量,从中比较各种收缩徐变预测模型之间的差异,得出ACI 209预测模型收缩徐变的发展主要集中在前期,CEB-FIP(1978)模型预测值偏于保守,JTG D62-2004和CEB-FIP(1990)预测值处于前两者之间;(2)将三次健康监测实测的主梁挠度进行温度修正,得到经温度修正后的收缩徐变对主梁挠度影响的实测值,并将这一结果和不同收缩徐变预测模型的计算结果进行对比,选出和实测数据最相近的收缩徐变预测模型,得出JTG D62-2004预测模型的计算值比较符合实测值,CEB-FIP(1978)预测模型的计算值与实测值偏离最大;(3)根据成桥试验中的静动力实测数据对八里湖大桥进行有限元模型修正,在待修正参数的选择上采用灵敏度分析,联合静动力特性构建目标函数,采用粒子群优化算法对目标函数进行优化,最终得到修正后的有限元模型。在修正后的模型中,虽然在部分响应值的误差有所增大,但是无论是静力位移还是动力频率在整体上都较模型修正前与实测值有了更好的吻合。
[Abstract]:For the concrete cable-stayed bridge, as a kind of aging material, the shrinkage and creep characteristics of concrete play an important role in the long-term deformation of the structure, and have different structural forms. The effects of shrinkage and creep on the mechanical performance of the bridge are different in different operation periods, so it is necessary to study the effect of shrinkage and creep on the bridge during the operation period. At the same time, when the initial finite element model is established, the actual situation is simplified and assumed because of the need of the actual modeling. The static and dynamic responses calculated by the initial finite element model based on the design drawings are often different from the measured values to varying degrees. How to modify the initial finite element model so that the calculated value of the modified model is closer to the measured value is a direction worth studying. In view of the above two points, this paper takes the Balihu Bridge as the background, and does the following work: (1) using the different shrinkage and creep prediction model to carry on the theoretical calculation and analysis to the Balihu Bridge, The deflection of the main girder, the cable force of the stayed cable and the deflection of the top of the tower are calculated respectively after the completion of the bridge, and the differences between the various models of shrinkage and creep prediction are compared. It is concluded that the development of ACI 209 prediction model is mainly concentrated in the early stage, the prediction value of CEB-FIP (1978) model is conservative, and that of JTG D62-2004 and CEB-FIP (1990) is between the former two. (2) the deflection of the main beam measured by three times health monitoring is corrected by temperature, and the measured value of the effect of shrinkage and creep on the deflection of the main beam after temperature correction is obtained, and the results are compared with the calculated results of different shrinkage and creep prediction models. The model of shrinkage and creep prediction, which is the closest to the measured data, is selected. The calculated values of JTG D62-2004 model are in good agreement with the measured values. The deviation between the calculated values of CEB-FIP (1978) prediction model and the measured values is the largest. (3) based on the static and dynamic measured data of the bridge, the finite element model of the bridge is modified. The sensitivity analysis is used to select the parameters to be corrected, and the objective function is constructed by combining the static and dynamic characteristics. Particle swarm optimization (PSO) algorithm is used to optimize the objective function and the modified finite element model is obtained. In the modified model, although the error of partial response value is increased, both static displacement and dynamic frequency are in good agreement with the measured values on the whole.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U448.27

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