温度影响下混凝土简支梁有限元模型修正损伤识别方法研究

发布时间：2019-05-06 14:10

【摘要】：随着我国国民经济的快速发展,桥梁工程领域有了飞跃式的进步。桥梁在交通运输系统中发挥着重要作用,保证桥梁结构的安全使用对国民经济的发展和人们生命财产安全具有重要意义。然而,桥梁在服役过程中,不可避免地受到长期荷载与环境因素等影响,导致结构发生损伤,甚至倒塌。大量研究结果表明,环境因素,特别是温度会造成桥梁结构动力特性的显著改变,并可能掩盖了由于结构损伤对动力特性的影响,因此,研究温度对桥梁模态参数产生的影响,以及在温度影响下,提出有效的损伤识别方法具有重要的现实意义。本文在对一钢筋混凝土简支梁的长期监测基础上,研究了混凝土简支梁温度场分布特点,从理论上分析了温度对模态参数的影响机理,通过有限元分析方法构建基准模型,实现了环境温度影响下,基于有限元模型修正的损伤识别。本文研究的主要内容如下:1、通过对一室外混凝土简支梁的长期监测,研究了环境温度对简支梁模态参数的变化规律与影响机理,通过对实测温度数据进行分析,阐明了简支梁模态频率变化与环境温度场分布的负相关性,并说明温度主要通过改变混凝土弹性模量从而导致模态频率的变化。2、运用有限元分析软件ANSYS构建简支梁模型,模拟实际温度场,从理论上研究温度不均匀分布对模态频率的影响,构建出已知温度场下的基准模型。然后,分析了已知温度场条件下的模态频率计算方法。3、采用对损伤极为敏感的柔度矩阵,并提出柔度残差概念,将柔度残差作为目标函数,利用实测模态数据和有限元模型计算出的模态信息,基于灵敏度与Tikhonov正则化方法相结合的模型修正方法,通过修正混凝土弹性模量值使得各节点柔度残差值接近于0,使得有限元模型和实际结构相吻合。4、最后,利用柔度差曲率进行损伤定位与定量识别,对混凝土简支梁有限元模型进行不同位置和不同损伤程度的损伤模拟,通过数值模拟,结果表明该方法能够有效识别出结构的损伤位置,实现损伤识别。
[Abstract]:With the rapid development of our national economy, the bridge engineering field has made great progress. The bridge plays an important role in the transportation system. It is of great significance to ensure the safe use of the bridge structure for the development of the national economy and the safety of people's life and property. However, in the course of service, bridge is inevitably affected by long-term load and environmental factors, resulting in structural damage and even collapse. A large number of research results show that environmental factors, especially temperature, will cause significant changes in the dynamic characteristics of bridge structures, and may mask the influence of structural damage on the dynamic characteristics of bridges. Therefore, the influence of temperature on modal parameters of bridges is studied. And under the influence of temperature, it is of great practical significance to propose an effective damage identification method. In this paper, based on the long-term monitoring of a reinforced concrete simply supported beam, the distribution characteristics of the temperature field of the simply supported concrete beam are studied, the influence mechanism of temperature on modal parameters is analyzed theoretically, and the benchmark model is constructed by the finite element analysis method. The damage identification based on finite element model modification is realized under the influence of ambient temperature. The main contents of this paper are as follows: 1. Through the long-term monitoring of a simply supported concrete beam outside the room, the variation rule and influence mechanism of the ambient temperature on the modal parameters of the simply supported beam are studied, and the measured temperature data are analyzed. The negative correlation between modal frequency change and ambient temperature field distribution of simply supported beam is expounded, and the change of modal frequency is mainly caused by changing the elastic modulus of concrete. 2. The finite element analysis software ANSYS is used to construct the simple supported beam model. By simulating the actual temperature field, the influence of non-uniform temperature distribution on modal frequency is studied theoretically, and the reference model under known temperature field is constructed. Thirdly, the flexibility matrix, which is very sensitive to damage, is adopted, and the concept of flexibility residual is put forward, and the flexibility residual is regarded as the objective function. Based on the measured modal data and modal information calculated by the finite element model, based on the model correction method based on the combination of sensitivity and Tikhonov regularization method, the flexibility residual value of each node is close to 0 by modifying the elastic modulus value of concrete. The finite element model is consistent with the actual structure. 4. Finally, the damage location and quantitative identification are carried out by using the flexibility difference curvature to simulate the damage of the finite element model of simply supported concrete beams in different positions and different degrees of damage. The numerical simulation results show that the proposed method can effectively identify the damage location of the structure and realize the damage identification.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U446

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