The Pressure Connecting Pipe Factors In Dynamic Monitoring Precision Deflection Effect

Bridge displacement under external load and environmental factors, reflects the overall stiffness of the bridge structure, is an important parameter in bridge condition assessment of the structural safety. In order to grasp whether the bridge structure has a mutation or abnormal happens, the real-time dynamic monitoring of the deflection is very necessary. Connecting pipe displacement monitoring system with the advantages of high precision, free from multi-directional deformation and live adverse environmental impact, etc, and have a clear advantage in the economy, durability and so on, has been widely used on the ground subsidence, dam and bridge structures static deformation monitoring in recent years. Pressure field connecting tube is determined by measuring the change in the hydraulic tube to acquire structural displacement, currently, its application and research mostly use static measurements as a precondition and displacement measurement study for structural dynamic was relatively small, Therefore, to carry out the study of parametric of measurement accuracy by dynamic pressure field communicating tube has important significance. This article focuses on the impact of arrangement for connecting pipe bending and bending vibration of the bridge on the bridge structure deflection measurement accuracy impact study. Main work is as follows:(1) Selection of Pressure Transmitters. Through the comparison of the measurement accuracy and performance dynamic mainstream of five kinds of differential pressure transmitter in current market, and use a large continuous rigid frame bridge in south China as the background, proposed the structural properties of the pressure transmitter selection method. In the selection of pressure transmitter, the measurement accuracy is mainly affected by structural deflection values affect the dynamic performance is affected by structural vibration frequencies affected.(2) Elbow arrangement for measurement accuracy. Affected by the piping elevation, connecting pipe bending arrangement may exist. Based on ANSYS-FLOTRAN finite element calculation results and the actual results of the comparative analysis showed that the bending arrangement has less impact on the measurement results, it only impact pressure distribution within1.5m from the upper end of the elbow. In practice, to avoid the affected area can basically meet the actual measurement accuracy requirements.(3) The effection of structural vibration acceleration. Based on model experiments and field measurements, using theoretical analysis method to study the structure connecting pipe attached to the pressure within the law affected by the vibration acceleration. Research shows that the structure seriously affect the structural vibration acceleration measurement accuracy, due to structural vibration caused mainly by the variation of pressure tube acceleration, and the communicating pipe height of. Based on the theoretical analysis, the establishment of additional pressure and acceleration, and a function of the communication pipe height, and through model tests and field tests verify the reliability of the formula.