Research on Establishing Scouring Monitoring System of Bridge Management by using Wireless Sensor Network

• Main Authors: Jui-Pang Lo, 羅瑞邦
• Other Authors: Hui-Ping Tserng
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/e5ckrn

碩士 === 國立臺灣大學 === 土木工程學研究所 === 106 === Along with the global climate change, the extreme events are happening with increasing frequency, increasing the risk of bridge scouring. However, in Taiwan, rivers are usually short, with swift current and most of them are left unattended. Therefore, how to monitor the scouring of bridges effectively is a very important issue. The objects of this study is to use the finite element model to investigate the relationship between scouring depth of pier and the natural frequency, and to develop a self-made Wireless Sensor Network (WSN), conducting micro-vibration test on structure, then obtaining the natural frequency of bridge pier through converting the time series via Fast Fourier Transform (FFT). Finally, comparing the natural frequency obtained by WSN and finite element model, the scouring state of bridge can be determined. This study developed a self-made Wireless Sensor Network, specially for in-situ test, using open source development tools: Arduino Uno, Xbee wireless transmission module, etc., and adopting two different types of analog accelerometers (KB12VD and SD2210). A series of tests and corrections have been carried out for the WSN system and through comparing the WSN system with the commercial instrument, the limitations and applicability of the instrument can be clarified. Then selecting the more appropriate hardware and software collocation, the natural frequency of the structure can be effectively measured. This study took Wenhe Bridge in Wenshan District, of Taipei City as an example. The completed drawings were collected as well as the finite element model of bridge was built with SAP2000 software. Various parameters and conditions were settled carefully and STP-N values were used to simulate the boundary conditions of soil. The modal analysis was conducted to investigate the relationship between scouring depth of pier and the natural frequency. The simulation results of model show that the natural frequency of the bridge pier without scouring is 4.361 Hz. Using the self-made WSN system, the natural frequency of the Wenhe Bridge is 4.328 Hz. The comparison of natural frequency obtained by the SAP model and WSN system shows that the Wenhe Bridge is close to the initial state of unscouring. Finally, through the actual measurement of the infrastructure, the overburden depth of pier is close to the initial state, verifying that the overall standardization process is feasible.