基于动力特性的某在役PC桥梁健全性评估

发布时间：2018-10-08 17:19

【摘要】：桥梁是交通运输的枢纽和命脉,在社会经济发展中起着至关重要的作用。然而,桥梁在服役年限内受各种因素的影响,将出现不同程度的损伤和劣化等病害问题。在众多桥梁损伤识别方法中,基于结构动力特性的损伤识别方法是表征结构整体状态最好的宏观标识量。以往研究表明,利用现场动载试验和数值分析相结合的方法,能够很好地评估刚架桥的健全性。目前,利用这种方法对预应力混凝土(Pre-stressed concrete,简称PC)桥梁健全性评估的研究还比较少。本文采用现场动载试验测定PC连续梁桥的动力特性。在动载试验中,采用42个高灵敏度伺服式加速度计和无线局域网振动系统测定桥梁的振动加速度,试验在封闭交通的环境下进行。同时,对该PC桥梁进行数值分析。通过现场动载试验和数值分析相结合的方法,基于频率变化和振型变化对PC桥梁进行损伤识别,进而对该桥梁健全性进行评估,同时为同类型桥梁健全性评估提供参考。主要研究内容如下:1)采用环境激励振动试验对PC连续桥梁动力特性进行测试。研究表明:环境激励下振动试验能够测得桥梁的自振频率和振动模态;2)本文中对比了桥梁现场动载试验所测得振型和有限元数值分析所得振型,通过对比则可知:利用大型车辆通行的激振方式对PC桥梁进行现场动载试验,只在很小的范围内准确反应桥梁动力特性;3)对比了动载试验和数值分析自振频率,动载试验所测得的频率与有限元分析所得频率有一定的差异,可能是由于有限元分析时将钢筋、钢绞线进行简化及支撑条件的影响;4)对比了桥梁建设初期和使用50年后桥梁自振频率。该桥梁结构在使用50年后,自振频率降低。在很大程度上是由于增设人行道的影响;桥梁使用过程中材料劣化则影响次之;最后,桥梁建设初期振动试验的测量精度也有一定程度的影响。
[Abstract]:Bridge is the hub and lifeline of transportation and plays a vital role in the development of social economy. However, due to the influence of various factors during the service life of the bridge, the damage and deterioration will occur in varying degrees. Among the many damage identification methods for bridges, the damage identification method based on the dynamic characteristics of structures is the best macro marker to characterize the overall state of the structure. Previous studies have shown that the method of field dynamic load test and numerical analysis can be used to evaluate the soundness of rigid frame bridge. At present, there are few researches on the evaluation of the bridge health of prestressed concrete (Pre-stressed concrete,) bridge with this method. In this paper, the dynamic characteristics of PC continuous beam bridge are measured by field dynamic load test. In the dynamic load test, 42 high sensitivity servo accelerometers and WLAN vibration system are used to measure the vibration acceleration of the bridge. The test is carried out in the closed traffic environment. At the same time, the PC bridge is numerically analyzed. Through the combination of field dynamic load test and numerical analysis, the damage identification of PC bridge based on frequency change and mode change is carried out, and then the bridge's health is evaluated, and the reference is provided for the same type of bridge's soundness assessment at the same time. The main research contents are as follows: (1) the dynamic characteristics of PC continuous bridge are measured by ambient vibration test. The results show that the natural vibration frequency and vibration mode of the bridge can be measured by the vibration test under environmental excitation. In this paper, the vibration modes obtained from the field dynamic load test of the bridge are compared with those obtained by the finite element numerical analysis. By comparison, it can be seen that the field dynamic load test of PC bridge is carried out by using the excitation mode of large vehicle passing, and the dynamic characteristics of the bridge are accurately reflected in a very small range. (3) the dynamic load test and the numerical analysis of the natural vibration frequency are compared. The frequency measured by the dynamic load test is different from the frequency obtained by the finite element analysis, which may be due to the reinforcement bar being used in the finite element analysis. Comparison of the natural vibration frequencies between the initial construction of the bridge and 50 years after use. The natural vibration frequency of the bridge structure decreases after 50 years of service. To a large extent, it is due to the influence of the addition of sidewalks; the deterioration of materials in the process of bridge use is the second; finally, the measurement accuracy of vibration test in the initial stage of bridge construction is also affected to a certain extent.
【学位授予单位】：河南理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U446

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