Development Of New Types Of FBG Sensors & Structural Health Monitoring And Analysis Of The Whole Engineering Modification Process Of A Steal Beam

For many years, accidents occur frequently in civil engineering which makes structural health monitoring (SHM) of civil structures indispensable to guarantee the safety, integrity and durability of the major engineering during the construction, operation and transformation. Recently, SHM has been a hot research area. The preferred sensing element is fiber Bragg grating (FBG) sensor with respect to its excellent performance. In this article, a grip-packaged FBG micro-displacement sensor and a smart temperature self-compensation bolt are presented. Then conclusions are made based on real-time monitoring and analysis of the cutting process of a steel platform beam in a manufacturing workshop. The content of this article is as listed below.(1) The characteristics of several kinds of FBG sensors developed in this paper are introduced. A new grip-packaged FBG micro-displacement sensor is developed based upon the available micro FBG sensors and the practical engineering needs. The calibration results of the micro FBG displacement sensors indicate that the performance is stable and capable to be used in actual engineering.(2) A smart temperature self-compensation bolt is developed with the ability to monitor the strain change. It can make use of the high sensitivity of the sensitized FBG strain sensors encapsulated in capillary tube to increase the measurement accuracy and minimize the measurement errors caused by the temperature change utilizing the function of temperature self-compensation. The smart bolt is easy to install and the data acquisition is convenient to operate which can be widespread used at joints of key members of different kinds of structures.(3) To insure the safety of cutting process of a steel platform beam subjected to equipment load in a manufacturing workshop, the cutting process is studied with finite element analysis and monitored using Fiber Brag Grating (FBG) sensors. The cutting plan of the beam is determined by the analysis of the temperature field of the beam at high temperature. The analysis results can also provide basis for the design of the structural health monitoring (SHM) system, the layout of the sensors and the threshold value of the alarm system during the real-time monitoring. During the cutting process, the monitoring data collected by the SHM system is analyzed in time to estimate the condition of the beam and ensure the operation smooth. The monitoring results indicate that the stress states of the beam can be evaluated based on the monitoring plan and provide guidance for the speed of the cutting machine. And the FBG strain sensors and temperature sensors satisfy the requirements of high-temperature operation. The successful application of visual monitoring plan for rapid alert can provide a basis for similar structural transform.