大跨度连续刚构桥健康监测几个关键问题研究

发布时间：2018-03-29 18:31

本文选题：预应力混凝土连续刚构　切入点：结构健康监测　出处：《北京工业大学》2014年硕士论文

【摘要】：连续刚构桥作为一种成熟的桥型在我国得到了广泛的应用。然而，由于受材料特性、施工工艺等因素影响，预应力混凝土连续刚构桥在通车运营中极易出现主梁下挠、箱梁开裂、有效预应力降低、钢筋锈蚀、整体刚度降低等病害，给桥梁结构的安全使用造成了隐患。为保证桥梁结构安全运营，越来越多的大型桥梁建立了健康监测系统，以及时有效的发现桥梁结构的病害并迅速做出处治。本文以一座三跨预应力混凝土连续刚构桥为工程背景，对大跨径预应力混凝土连续刚构桥的健康监测系统搭建、参数识别、有限元模型修正以及环境温度对结构动力参数的影响等几个问题进行了分析研究，主要的研究工作及成果包括如下：（1）预应力混凝土连续刚构桥梁健康监测方案、传感器布设及健康监测系统的集成。依据密关路白河大桥的设计文件，考虑结构实际受力特点，完成健康监测方案的制定，并根据传感器优化布置的方法完成了所有传感器的布设，对健康监测系统进行集成，实现对白河大桥的实时监测。（2）基于环境激励的预应力混凝土连续刚构桥模态参数识别方法。基于已建成的健康监测系统，选取一段实测数据，分别采用频域分解法与随机子空间结合稳定图的方法，对白河大桥进行模态参数识别分析。结果表明，这两种方法识别结果基本一致，能够适用于预应力混凝土连续刚构桥的参数识别。（3）基于参数灵敏度的预应力混凝土连续刚构桥有限元模型修正。以设计文件为依据，采用实体单元建立全桥初始有限元模型。将有限元计算结果与实测模态参数比较发现，各阶频率均存在较大误差，最大误差超过10%。通过参数进行灵敏度分析，选取灵敏度较高的参数为待修正参数，以实测模态参数为修正目标，，综合运用零阶法与一阶法对初始有限元模型进行模型修正，得到基准有限元模型。结果表明，选择高敏感度参数进行模型修正，能够大大加快优化收敛速度；修正后的有限元模型计算频率大大逼近于环境激励下的实测频率，前八阶自振频率计算值与实测值之间误差均在3%以内，并且在优化修正过程中，结构变量始终在预先设定的区间内变化，使得模型修正结果不会偏离其实际物理意义。（4）基于长期监测数据的温度对桥梁动力特性的影响研究。根据健康监测系统的一年多的实测数据，对结构不同时间的动力特性进行参数识别，并进行统计分析。结果表明，对于连续刚构桥梁，其模态频率变化与环境温度变化具有明显的负相关性，且低阶模态频率比高阶模态频率受温度变化的影响更为显著。
[Abstract]:Continuous rigid frame bridge, as a mature bridge type, has been widely used in China. However, due to the influence of material characteristics and construction technology, prestressed concrete continuous rigid frame bridge is prone to appear the deflection of the main beam during the operation. The cracking of box girder, the reduction of effective prestress, the corrosion of steel bar and the decrease of overall stiffness have caused hidden trouble to the safe use of bridge structure. In order to ensure the safe operation of bridge structure, more and more large bridges have established health monitoring system. In order to find the damage of the bridge structure in time and effectively and to deal with it quickly. This paper takes a three-span prestressed concrete continuous rigid frame bridge as the engineering background to build the health monitoring system and parameter identification of the long-span prestressed concrete continuous rigid frame bridge. Several problems, such as the modification of finite element model and the influence of ambient temperature on the dynamic parameters of the structure, are analyzed and studied. The main research work and results are as follows:. 1) the health monitoring scheme of prestressed concrete continuous rigid frame bridge, the integration of sensor layout and health monitoring system. According to the design documents of Miguan Road Baihe Bridge, considering the actual stress characteristics of the structure, the health monitoring scheme is formulated. According to the method of optimal arrangement of sensors, all sensors are arranged, and the health monitoring system is integrated to realize the real-time monitoring of Baihe Bridge. (2) the modal parameter identification method of prestressed concrete continuous rigid frame bridge based on environmental excitation. Based on the established health monitoring system, a section of measured data is selected, and the frequency domain decomposition method and random subspace method are used to combine the stability diagram, respectively. The modal parameter identification analysis of Baihe Bridge shows that the two methods are basically consistent with each other and can be applied to the parameter identification of prestressed concrete continuous rigid frame bridge. The finite element model of prestressed concrete continuous rigid frame bridge is modified based on parameter sensitivity. Based on the design file, the initial finite element model of the whole bridge is established by using solid element. The results of finite element calculation are compared with the measured modal parameters. There are large errors in each order frequency, and the maximum error is more than 10. Through the sensitivity analysis of the parameters, the parameters with high sensitivity are selected as the parameters to be corrected, and the measured modal parameters are taken as the correction targets. The model of the initial finite element model is modified by the zero-order method and the first-order method, and the benchmark finite element model is obtained. The results show that the optimization convergence rate can be greatly accelerated by choosing the highly sensitive parameters to modify the model. The calculated frequency of the modified finite element model is much closer to the measured frequency under ambient excitation. The error between the first eight natural vibration frequencies and the measured values is within 3%, and in the process of optimization and correction, the error between the calculated frequency and the measured frequency is less than 3%. The structural variables always change in the predefined interval, so that the model correction results will not deviate from its actual physical meaning. Based on the temperature of long-term monitoring data, the influence of temperature on the dynamic characteristics of bridges is studied. According to the measured data of more than one year from the health monitoring system, the dynamic characteristics of structures at different times are identified and analyzed statistically. For the continuous rigid frame bridge, the modal frequency change has obvious negative correlation with the ambient temperature change, and the low-order modal frequency is more significantly affected by the temperature change than the high-order modal frequency.
【学位授予单位】：北京工业大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U446

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