Hongfeng Lake Bridge Health Monitoring And Evaluation System, Data Processing And Realization

The health status of bridge is derived from sensors real-time monitoring data. The bridge health monitoring system will collect real-time data and diagnosed the injury. The cable tension calculation and modal parameter identification are the key components of bridge health monitoring system.Cable tension monitoring system is the key element of a cable-stayed bridge health monitoring system. Fundamental Frequency method is one of Cable tension calculation methods that used widely for tension evaluation and condition assessment of cable-stayed bridge. There is a unique relationship between the tension and fundamental frequency of the stay cable. The key to success of this technique is the accuracy of identified fundamental frequency of each stay cable. In this paper, a fundamental frequency identification method is presented based auto-correlation function. Using this method, the system can identify fundamental frequency accurately in the case of interference. It has been used for Hongfeng Lake Bridge Health Monitoring System and the result is good.The aim of bridge health monitoring system is the structure damage identification. The key for damage identification is modal parameter identification. The Peak Picking Method (PP) and parameter identification based HHT are used. PP is the simplest method for structure modal parameter identification. In this paper, the normal averaged power spectrum curve is used to calculate the natural frequency. PP is suitable to the structure with little damping ratio.EMD is used to the bridge vibration signal to derive the IMF and the residue. And further RDT and HT are used to derive natural frequency and damping ratio. Proved by the actual measured data, HHT method is a good for large-scale bridge modal parameter identification.