On The Health Monitoring System Of Long-Span Bridge Based On GPS Technique

In recent years, more and more long-span bridges are built along with the development of national economy, and bridge health monitoring is becoming research focus of civil engineering field. With the development of GPS technique, it has provided a new way for the bridge health monitoring application. Presently, some long-span bridge health monitoring system based on GPS technique has been developed and set up in the field successfully. While the monitoring system operating continuously, the quantity of monitoring data expands rapidly. In order to visualize outputs of monitoring data and analysis it, visualization technique comes into area of bridge health monitoring system gradually.The concept of bridge health monitoring is put forward firstly, and the purpose, meaning and necessity of it are discussed. Then the paper introduces correlative subjects which the system building up needs in detail, such as GPS positioning, OpenGL visualization, bridge structural analysis and health evaluation, etc.The integrated overall design proposal of long-span bridge health monitoring system based on GPS is advanced, according to design criteria of bridge health monitoring system. The system includes hardware and software compose, designing method of monitoring item, disposal of GPS measuring points, data collection and transmission project adapted to the long-span bridge health monitoring system based on GPS, and data processing and analysis method during system running.As a research emphasis of the paper, a bridge dynamic demo system of real time monitoring displacement is built up, taking three-span two-hinged suspension bridge as an example. The development tool is Visual C++ 6.0 and the graphic interface is OpenGL. The system absorbs a series of OpenGL advanced characteristic such as solid modeling, lighting, texture mapping, and so on. After system calculating the bridge instantaneous shape from monitoring data, real time solid modeling of bridge starts on, and then on-line three-dimensional model of the bridge and time travel curve of measuring points are displayed. In the end, the system adds some functions such as start-up, stopping, quitting, view selecting andsize scaling, etc.Eventually, the paper makes a preliminary conceive about the function of calculating structure stress from structure displacement in the bridge health evaluation system, and introduces the analyzing of bridge structural dynamic characteristic. According to the required function of bridge health evaluation system, the organizing flow of bridge health evaluation system is presented as a whole, and the system function is analyzed, relating to the implementing of the forecast function.