Construction Of Building Structure Health Monitoring System Under The Framework Of Internet Of Things

Long-term lack of maintenance and sudden disaster events are the main reasons for the sudden collapse of building structures.The research and application of building structure health monitoring technology can not only improve the safety and reliability of building structures,but also reduce the cost of building maintenance and reconstruction,and provide security for the long-term use of buildings.This paper will develop a building structure health monitoring system based on the Internet of Things platform,which is used for real-time acquisition of building structure vibration information,and processing and analysis of the acquired information,so as to achieve longterm monitoring of building structure health status,to ensure its safe and stable operation.The main contents are as follows:(1)A low cost,low power consumption,high sensitivity,long-term online building structure health monitoring system is developed.The acceleration sensor adopts MEMS sensor with high sensitivity and economic benefit,and uses LTE-Cat1 module for communication.The microcontroller is used to process and transmit vibration signals collected by the accelerometer.RTC startup program and threshold triggering startup program are designed to reduce the power consumption of the sensor.The Internet of Things platform was built to receive sensor data from the device side,and SQLite lightweight database was used to store these data.Meanwhile,the upper computer terminal was developed to manage the monitoring targets in a unified manner.(2)Due to the influence of external environment and equipment accuracy,vibration signals will generate a lot of noise in the process of collection and transmission.In order to extract useful information in the collected signals,the wavelet transform which can be analyzed in the time-frequency domain at the same time is used as the denoising method of vibration signals in the monitoring process.The denoising effect of different wavelet basis function,decomposition layer number and threshold function in vibration signal processing is studied.sym4 wavelet basis function with the best denoising effect and other appropriate parameters are selected.The results show that using wavelet analysis to denoise the measured signal can better observe the vibration of the structure itself.After the processed vibration signals were obtained,peak value method(PP)and Covariance-driven random subspace identification method(SSI-COV)were used to identify the modal parameters of the tested structure,so as to master the dynamic parameters of the structure and evaluate the basic health status of the structure.(3)The developed monitoring equipment is used to carry out the model test of steel-glass footbridge and outdoor footbridge test.In the model of steel-glass footbridge,the test results of the developed monitoring system are compared with the commercial monitoring equipment to verify the reliability of the developed monitoring system.Then the monitoring system was applied to the outdoor footbridge in service,and the vibration signals of the footbridge collected by the sensor system were analyzed and processed with Matlab program,the modal parameters of the footbridge were extracted,and the health state of the structure was evaluated.