Research And Application On The Crack Remote Monitoring System For Concrete Bridge

Bridges play a significant role in the traffic and transportation. With the rapidgrowth of the national economy, a large number of bridges have been constructed. Dueto low cost and abundant raw materials, concrete bridges are widely used. In recentyears, concrete bridges collapse frequently, the number of disease reports continues toincrease, and cracking is a most typical phenomenon. Therefore, cracks of concretebridges must be monitored effectively for reinforcement and maintenance in advance,aimed to prevent secondary diseases due to crack propagation.Crack monitoring is one of the most challenging issues in the field of structuralhealth monitoring. Over the past several years, lots of researches on crack monitoringhave been carried out and some progress has been made, such as the point monitoring,distributed monitoring based on optical fiber sensors, electrical time domainreflectometry technology based on coaxial cable and image recognition monitoringmethod. These methods can be used to monitor cracks in a certain extent, but thedrawbacks make them unavailable in engineering practice. Smart film crack monitoringtechnique proposed by a research team of Chongqing Jiaotong University is an effectiveway for monitoring initiation, length, width, shape, location and propagation of cracks.Because of simple fabrication and installation, it is suitable for the engineering practice.This paper analyzes and designs the remote crack monitoring systems of concretebridges which are based on smart film crack sensors. Two main problems of thepractical monitoring system are solved. One of them is the selection of monitoringlocation of the smart film crack sensor. In the paper, the installation locations of sensorson the same concrete bridges are analyzed and selected according to the statistics ofman-operated detection along with finite element analysis. The other is design ofsoftware and hardware for collecting, transmitting, storing, processing data of cracksensors. Then crack data is sent to the remote monitoring center, analyzed and recurreddata through the server of the center. And then the safety condition is evaluated. Afterfinishing the system design, the system is to be tested by experiments. Besides,combining with monitoring data of the practical applications, the monitoring effects ofthe system are discussed.The main contents of this paper include:(1) Combining the statistics of cracklocation by the man-operated detection with finite element analysis method, the locations where cracks are easy to emerge are analyzed, which can provide an accuratereference for installed locations of smart film crack sensors.(2) Relevant software andhardware are designed so as to transmit, store and recur crack sensing data.(3)According to the concrete girder model in the university, an experimental system isestablished to produce artificially some cracks, thus the durability, reliability andstability of the system are verified.(4) Combining with monitoring data on two bridges,including Tukan Wujiang River Bridge and Masangxi Yangtze River Bridge, themonitoring effects of the system are discussed.