| With the continuous development of the social economic level,a large number of public facilities have also been built.The space grid structure has been widely used in the construction of large public facilities such as stations,airports and stadiums because of its advantages of light weight,high rigidity and good seismic performance.The gird structure has many components and the stress state is complex.Under the influence of various factors such as loading,aging of materials and environmental corrosion,its structure is prone to catastrophic,and there have been many accidents at home and abroad that caused the loss of people’s lives and property due to the catastrophic of grid structure.The grid structural stress is one of the key indicators to evaluate and measure the safety status of the structure.Thus the stress monitoring of the grid structure is of great significance to the evaluation and protection of structural safety.In view of the insufficiency of the existing grid structure stress monitoring technology,this paper has independently developed a low temperature sensitive fiber grating strain sensor and applied it to the construction process monitoring of the stadium structure of Zhengzhou Olympic sports center and the stain monitoring of structural components of transmission towers.Good monitoring results have been achieved in the above projects.The structure of this paper is as follows:In the first chapter,the development history and structural characteristics of the grid structure were first introduced and the necessity of structural stress monitoring was also described.Then it described the development and application status of grid stress monitoring technology and FBG strain monitoring technology and the current deficiencies in stress monitoring of grid structure.Finally,the main research content of this paper was introduced.In the second chapter,the difficulties of FBG strain monitoring technology was analyzed,and a novel low temperature sensitive FBG strain sensor was proposed in combination with the existing FBG sensor packaging technology.Then the strain and temperature calibration experiments were performed on the sensor and the experimental results show that the sensor has good strain sensitization and temperature desensitization characteristics.In addition,the fatigue load tests were performed on the sensors to verify their long term stability and repeatability.The third chapter mainly introduces the application of low temperature sensitive FBG strain sensor in Zhengzhou Olympic sports center gymnasium grid structure strain monitoring system.The unloading process of the grid structure was monitored,and its structural response law was obtained and compared with the finite element results.The actual monitoring data proves that the self-developed sensor has good low temperature sensitivity characteristics and can solve the problem of temperature drift of the pervious FBG sensors,and also greatly simplifies the workload of subsequent data processing.In the fourth chapter,the application of low temperature sensitive FBG sensor in the strain monitoring of structural components of transmission towers was introduced.Based on the special structural characteristics and installation environment of transmission towers,an U-shaped fixture was designed for sensor installation and the effect of U-shaped clamps on strain transfer of sensor was also studied.During the landing of the “Tiange” typhoon in 2017,the low temperature sensitive FBG strain sensor was working normally,responds sensitively and has stable performance.A large number of structural strain response data of transmission towers were obtained.Based on the measured data,the strain response law of the transmission tower structure and its safety status was analyzed. |
