城市简支梁桥损伤识别的挠度影响线法研究

发布时间：2018-09-12 20:52

【摘要】：城市桥梁作为城市交通的重要组成部分,其健康状态是交通运输系统正常运转的前提。随着桥梁服役时间增长,由于环境侵蚀、材料老化和荷载的长期效应、疲劳效应等原因,目前已有不少桥梁存在损伤,极大的影响了桥梁结构的正常使用。桥梁一旦发生破坏,将会造成严重的生命财产损失,影响社会安定。因此研究适合城市桥梁的损伤识别方法有重要的理论意义和工程应用价值。文章基于目前的工程结构损伤识别的研究现状,特别是基于影响线的损伤识别现状,分析了目前损伤识别存在的问题,针对简支梁桥,提出以损伤前后移动荷载作用下简支梁桥某点挠度的变化即简支梁桥挠度差值影响线为损伤标识量进行损伤识别的方法。主要工作与成果如下:(1)利用虚功原理推导简支梁损伤前后某点挠度差值影响线的解析式。得出当移动荷载位于损伤区域时,挠度差值与移动荷载位置成三次方关系,而在其它无损区域与移动荷载位置成线性关系,挠度差值在损伤位置到达峰值,由此提出基于挠度差值影响线的简支损伤识别方法。(2)根据损伤区域挠度差值与移动荷载作用位置成三次方关系,在无损区域与移动荷载作用位置成线性关系的特点,提出基于挠度差值影响线二阶导数的简支梁损伤识别方法。(3)移动荷载时程分析结果表明荷载移动载速度对挠度差值影响线有较大影响。荷载移动速度较大时,挠度差值影响线呈现较大的波动性和自由振动,无法用于损伤识别。荷载移动速度小于5Km/h时,挠度差值影响线呈线性变化,可以对损伤进行有效识别。(4)数值模拟和试验结果表明,利用挠度差值影响线对简支梁单一损伤的损伤位置情况有较好识别效果,对多处损伤识别不完全。利用挠度差值影响线二阶导数对简支梁单一损伤和多处损伤均有较好识别效果。
[Abstract]:As an important part of urban traffic, the healthy state of urban bridges is the premise of normal operation of transportation system. With the increase of service time of bridges, due to environmental erosion, material aging and long-term effects of load, fatigue effects and other reasons, there are many bridges damaged, greatly affecting the normal operation of the bridge structure. Once the bridge is destroyed, it will cause serious loss of life and property and affect social stability. Therefore, it is of great theoretical significance and engineering application value to study the damage identification method suitable for urban bridges. Aiming at the existing problems in damage identification of simply supported beam bridges, a damage identification method based on the change of deflection of a point under moving loads before and after damage, i.e. the influence line of deflection difference of simply supported beam bridges, is proposed. The analytical expression of the influence line of the deflection difference is obtained. When the moving load is located in the damage area, the deflection difference has a cubic relationship with the location of the moving load, while it has a linear relationship with the location of the moving load in other non-destructive areas, and the deflection difference reaches a peak value at the damage location. A simple support damage identification method based on the influence line of the deflection difference is proposed. (2) According to the cubic relationship between the deflection difference in the damage area and the location of the moving load, and the linear relationship between the damage area and the location of the moving load, a damage identification method for simply supported beams based on the second derivative of the influence line of the deflection difference is proposed. (3) Time history analysis of the moving load shows that the deflection difference is affected by the moving load velocity. The influence line of deflection difference has great influence. When the load moving speed is large, the influence line of deflection difference presents great fluctuation and free vibration, so it can not be used for damage identification. The second derivative of the influence line of deflection difference is used to identify the single damage and multiple damage of the simply supported beam.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U446

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