Vibration Environment Impact On Bridge Girder Deflection Monitoring Base On The Pressure Transmitters

Girders of long-span bridges will experience deflection durng their operationunder various environmental factors and loads, and accumulated deflection maylead to failure of bridges. Therefore, real-time monitoring of bridge girderdeflection has become an important component of bridge health monitoring systems.Various methods have been developed for bride deflection monitoring. Among thesemethods, interconnecting tube system is the most frequently used technique forbridge girder deflection monitoring. However, the performance of interconnectingtube system is limited by factors such as density of liquid, large-scale liquid flow,materials and size of pipe, gravitational field of measure environment. For thereason, one-end sealed pipe system is used to limit the flow of water, andperformance of the interconnecting tube system for bridge defection monitoring isoptimized. Performance of an interconnecting tube system installed on a bridgemodel is analyzed and tested. The effect of vibratory environment on deflectionmeasrurements is studied. The main contents of this paper are as follows.The sloshing of water in the base tank is simulated with ANSYS/LS-DYNA.The pressure at the bottom of the tank is obtained by applying vibratorydisplacement of different frequencies and amplitude to the base tank. The effect ofthe vibration to pressure is discussed, and hence to the the converted displacementby pressure is obtained.A bridge deflection monitoring system based on interconnecting tube on thescaled model of Binzhou Yellow River Bridge is established. The performance ofthe system is tested under static displacement, quasi-static displacement andpedestrian walking load. The deflection measurement accuracy of this system underthe three conditions is analyzed. The frequency response range of theinterconnecting tube system is obtained. It is shown that the system is suitable forlow-frequency vibration deflection measurements.In field measurements from the interconnecting tube systems of Nanxi YangtzeRiver Bridge and Qingshuipu Bridge are analyzed. The reliability of quasi staticdeflection measurement is checked by investigating the temperature change andtraffic load induced deflection. By comparing the the statistics of bridge deflection mreaurements by interconnecting tube system with those of GPS displacementmonitoring system, the measurement accuracy of the interconnecting tube systemunder vibration condition is obtained.