Research And Development On Fast Measurement System Of Bridge Deflection Curve

Bridges are the key transport hubs, the countries'critical infrastructures and playing an increasingly important role in modern transportations. Bridge Health Monitoring (BHM) is a crucial link for safety operation with the emergence of the bridges which are new structure, long span, complex architecture, etc. Bridge deflection is a key factor for bridge conditions detection, and an important indicator for bridge safety evaluation, which can reflect whether the deformation of the bridge is beyond its effective safe range.Deflection curve, i.e. the deflected shape of the bridge in the vertical direction, is usually measured in new-built bridges'acceptance, existing bridges'maintenance, and routine inspections. The majority of the existing methods for measuring deflection curves of bridges are performed by collecting and fitting the deflection data at just a few discrete points along the bridges, respectively. The smoothness of the deflected curves of bridges is related directly to the quantity of the measured points. Generally, the existing deflection-measuring technologies have been implemented mostly at a few discrete points due to the limitations of the measuring time and operating conveniences, furthermore, the continuous deflection curves couldn't be reproduced smoothly. Therefore, it is significant to design a novel system for measuring deflection curve of bridges fast, continuously, and smoothly.This paper presents a fast measurement system of bridge deflection curve reproduction system based on inclinometer, which can reconstruct the deflected shapes of bridges directly. The operation of the system is performed by utilizing the displacement transducer to determine the measuring intervals, using inclinometer to collect the angles of the measured points, calculating the deflection values, further applying the modified gradient mean filtering algorithm to filter the deflection data, and finally reproducing the deflection curves of bridges. In this study, the design scheme and measuring principle of the system are developed separately; the procedure of the modified gradient mean filtering algorithm, used to process the deflection data due to the inescapable interference during measurement, is described; the development processes of the system, including the measuring equipment, circuit designs and software architecture, are described detailed. The system can be precise and reliable to measure the angles of the measured points of bridges, and can reproduce the deflection curve fast and smoothly by the laboratory experimental verifications, including the static and regressive experiment, and can be applied to the real-life bridges effectively through the filed experimental verifications. As a matter of fact, the proposed system can be applied to not only bridges, but also roads, ground, tables, and others need to measure the curve. The system may be applied gradually widely because of the advantageous features: simple equipment, easy to realize, cost-effective, convenient operation, high availability, etc.