| With the passage of time,suffering by weight,static load,dynamic load,and other effect the bridge will produce deflection.The bridge deflection is an important parameter of structural stiffness,long-term monitoring deflection is one of the important means to guarantee the safety of the structure.Based on that the current pressure pipe method has strong adaptability and high precision measurement of other incomparable advantages,it has been widely used in bridge monitoring.To solve the problem of system environmental layout and the continuous power supplying,high cost,effective use of data and a series of other problems,is the key to the sustainable development of the monitoring system.This paper uses embedded bridge deflection monitoring system based on pressure field communicating pipe method which has been widely used,combines with the model test of simply supported beam,designes and completes the low power consumption,low cost,wireless remote data transmission bridge dynamic deflection monitoring system.The main research methods and results are as follows:(1)Integrated systemThe integrated system based on the connected tube pressure field method is mainly composed of three parts,the sensor subsystem,the signal acquisition subsystem and the wireless transmission subsystem:(1)Sensor subsystem.Based on the requirements of the accuracy of the monitoring system of 0.1mm and 4Hz,compared to the mainstream pressure transmitter accuracy parameters and response time,Rosemount 3051 CD pressure transmitter as the sensor subsystem;study the influence range,working environment,zero migration,placement and other factors on the system error,and combining with the bridge's actual situation set the range of the system is 0.76Kpa;in order to reduce the dynamic response time and meet 4Hz bridge dynamic deflection monitoring,the damping time of the pressure transmitter should be set to 0.21 s.(2)Signal acquisition subsystem.Through the comparison of the main types of acquisition card resolution and conversion error,sampling rate,anti-interference ability,precision and so on,Advantech company's ADAM-4117 as deflection monitoring system of the A / D converter,and a detailed description of the parameters and use.(3)Wireless transmission subsystem.Through comparative analysis the main wireless communication technology,with simple,expansion,network nodes,and low cost advantages of ZigBee technology as a local wireless transmission subsystem,based on power,memory,and sensitivity,the price factor,choose the chips,and completed the CC2530 terminal nodes and coordinator node transmission network design.(2)Combined with the analysis of beam experimental data verify the feasibility and accuracy of the integrated system,use time domain analysis and frequency domain analysis of mathematical methods for statistical analysis of the integrated system and a displacement sensor system synchronous monitoring data.The results show that the error is less than 3%,the correlation coefficients were greater than 0.8,P test values are greater than 0.05,indicating that data has a better correlation and there are no differences between the two data proportion coefficient and the theoretical value of;(3)Based on the transmission rate,coverage rate,cost and other factors,choose the 3G communication module for remote transmission of data.At the same time,the precision and stability requirements based on the choice of Beijing Zhenhong Albert technology limited production model for the 3G module,2HD750 W DTU and completed the design of the network module;(4)To improve the effective utilization and provide real-time data for early warning system data,and proposes to use the Web Service platform,and the "LAMP" model to build a data management system.The rear end of the platform design is completed through the installation,compiling,configuration files,Smooth function pretreatment operation,using HTML,CSS,JavaScript language platform front-end program,completed the design of the access system.. |
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