Three Hierarchy Bridges Performance Evaluation Method Based On Monitoring Data

Countries all of the world has huge numbers of infrastructure projects, lack of maintenance funding makes serious problems happened on the safety> durability and health of engineering Structure. How can we evaluation engineering structures effectively and improve the maintenance level correctly is an industry problem. In this paper, we focus on the bridge structure, by review the bridge performance evaluation methods and standards all of the world, from sensor technology and modal parameter identification theory two levels to think about how to improve bridge performance evaluation. Then we propose three hierarchy bridges performance evaluation method based on monitoring data. The main contents and innovations are mainly the following:The first is about long gauge FBG strain sensor technology. Good source of data is the premise of the structural performance evaluation. After several years’ development of structural health monitoring technology, a wide variety of sensor technology emerged, because of various limitations, the measurement data is difficult to assess the performance of the bridge structure. In this paper, we propose area distribution sensing technology based on the long gauge FBG strain sensor, achieve an accurate measurement of macro and micro structural parameters. At the same time, we make provisions on the sensor layout, installation, acquisition, storage of the general structures; Guarantee a stable data Sources for structural performance evaluation.The second is about long gauge FBG Strain Modal Analysis Theory. Modal parameter has been our most direct way to understand the structural performance status, How to accurately identify the structural modal parameters from the data have been difficult problems. In this paper, by extending the traditional displacement modal parameter identification theory, we improve the long gauge FBG strain modal analysis theory. Based on the identification of the basic structural parameters (such as frequency, damping, mode shapes and so on), Learn that strain frequency response function matrix contains more information of the structure, enabled the identification of deep parameters—Structural Strain flexibility. It laid a good theory foundation for the structure performance evaluation.The third is about the Identification of strain flexibility under the condition of unknown mass. This thesis studies the relationship between strain flexibility and strain FRF, and it is found that the value of strain FRF in the frequency of zero is equal to the strain flexibility coefficient. The calculation formulas of strain flexibility are respectively derived from real and complex FRF. The formula from the real FRF requires normalized strain mode shapes, while the formula from the latter requires the modal scaling factor of the structure. By using PolyMAX method, we can identify structure parameters directly under the measurement of strain FRF without knew the mass of the structure. This has important implications for engineering practice. While focus on the challenging problems of identify intensive modes under the traditional methods, we propose structure parameter identification method within a narrow band, not only reduces computational time but also get more accurate results. Provides a theoretical basis for deepper parameter identification of structural performance evaluation.The fourth is about three hierarchy bridges performance evaluation method. In countries around the world bridges performance evaluation specifications, it is certain to do the performance evaluation by manual inspection assisted with automated test equipment, this method is easy affected by subjective consciousness and it is difficult to obtain a continuous monitoring, so it cannot identify structure dynamics change. On this basis, we proposed three hierarchy bridges performance evaluation method. Relying on long gauge FBG sensor technology and long gauge FBG strain modal theory, mined valid structure information in monitoring data. Through the first level pre-processing data and alarm capability we can remove erroneous data, repair data anomalies, and found structural abnormalities; By the second level-depth parameter identification in higher quality data, we can do damage identification then wen can evaluate bridge performance; The third level rendering performance evaluation results of the second level history data accumulation, then we can do structural remaining life prediction.And bind this method with the traditional performance evaluation specifications. It aims to promote health monitoring data integrated into real structural performance evaluation process, enabled intelligent monitoring and dynamic evaluation.