温度对桥梁模态频率识别的影响研究

发布时间：2018-01-16 12:07

本文关键词：温度对桥梁模态频率识别的影响研究　出处：《吉林大学》2015年硕士论文　论文类型：学位论文

【摘要】：交通是社会经济发展大动脉,桥梁则是保障交通畅通的首要因素。为保证社会经济持续发展和进步,桥梁功能的完整性,尤其是安全性则显得尤为重要。统计数据表明,随着近年来我国基础设施建设大力发展,我国桥梁建设取得了举世瞩目的成就,每年有大量新桥陆续建成,为使公路桥梁安全运行,则需要对这些刚刚完工的桥梁进行承载力评定和必要的健康监测。另一方面,许多已建桥梁经过长期服役而缺少足够充分的管养,已经接近设计寿命；桥梁的老化和损坏的现象层出不穷,对既有桥梁进行可靠鉴定以及损伤识别则迫在眉睫。近年来,以振动的结构损伤为基础的识别方法在得到了广泛发展,同时也成为了土木工程的研究重点,而温度对桥梁模态频率的影响常常会掩盖桥梁损伤的存在。本文的实验研究旨在探求温度影响模态频率的内在机理,揭示温度对桥梁模态频率影响的规律,以及桥梁不同损伤下的模态频率变化规律,为有效的解决温度对季冻区桥梁损伤识别问题奠定基础。本文的主要研究成果及结论如下： ①本文研究了温度效应影响桥梁模态频率分析并得出以下结论：温度的变化改变混凝土的弹性模量是造成桥梁模态频率改变的主要原因,同时温度对混凝土桥梁模态频率的影响主要是通过改变混凝土力学的性质来实现的。 ②利用动载试验识别出小梁在不同温度下的模态频率。并做数据的相关性分析后,得出结论：桥梁的频率随环境温度的升高而降低,两者之间呈良好的线性负相关关系。 ③依托实际桥梁检测工程进行了桥梁温度、湿度的测试,并进行现场动载实验。结果表明桥梁的自振频率变化与外界环境变化表现出较好的相关性。同时,桥梁的自振频率与环境温度数值之间的相关系数较大,说明桥梁的自振频率的变化主要受温度的影响。在实际桥梁健康评价工作中,温度确实会对桥梁的模态频率识别产生影响。若在较低温度环境下测得的结构发生损伤后的模态频率,就可能得出该已损伤桥梁结构“没有损伤”,或者“运行状态良好”的错误结论。说明了在桥梁健康监测中,剔除环境因素对桥梁模态频率的淹没作用至关重要。
[Abstract]:Traffic is the main artery of social and economic development, and bridge is the primary factor to ensure the smooth flow of traffic. In order to ensure the sustainable development and progress of social economy, the integrity of bridge function is ensured. Especially security is particularly important. Statistics show that with the rapid development of infrastructure construction in recent years, bridge construction in China has made remarkable achievements, and a large number of new bridges have been built one after another every year. In order to ensure the safe operation of highway bridges, it is necessary to evaluate the carrying capacity and necessary health monitoring of these newly completed bridges. On the other hand, many of the bridges that have been built have been in service for a long time and lack sufficient management and maintenance. Close to design life; The aging and damage of bridges emerge in endlessly, so it is urgent to identify the existing bridges reliably and damage. In recent years, structural damage identification based on vibration has been widely developed. At the same time, it has become the focus of civil engineering research, and the influence of temperature on the bridge modal frequency will often cover up the existence of bridge damage. The purpose of this experiment is to explore the intrinsic mechanism of temperature influencing modal frequency. The influence of temperature on bridge modal frequency and the variation of bridge modal frequency under different damage conditions are revealed, which lays a foundation for the identification of bridge damage caused by temperature in seasonal frozen region. The main research results and conclusions are as follows: 1. This paper studies the effect of temperature on the modal frequency analysis of bridges and draws the following conclusions: the change of the elastic modulus of concrete is the main reason of the bridge modal frequency change. At the same time, the influence of temperature on the modal frequency of concrete bridges is mainly realized by changing the mechanical properties of concrete. (2) the modal frequencies of the trabeculae at different temperatures are identified by dynamic load test. After the correlation analysis of the data, it is concluded that the frequency of the bridge decreases with the increase of ambient temperature. There is a good linear negative correlation between the two. (3) based on the actual bridge detection project, the temperature and humidity of the bridge are tested, and the field dynamic load experiment is carried out. The results show that the natural vibration frequency of the bridge has a good correlation with the change of the external environment, and at the same time. The correlation coefficient between the natural vibration frequency of the bridge and the value of ambient temperature is large, which indicates that the change of the natural vibration frequency of the bridge is mainly affected by the temperature. The temperature does influence the modal frequency identification of the bridge. If the modal frequency of the damaged structure is measured in the lower temperature environment, it may be concluded that the damaged bridge structure has no damage. Or the wrong conclusion of "good running state" shows that it is very important to eliminate environmental factors in bridge health monitoring for bridge modal frequency inundation.
【学位授予单位】：吉林大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U441;U446

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