The Development And Application Of Fiber Bragg Grating Strain Sensor In A Wide Range

To discover damage location of the structure and to evaluate its security and predict its residual life, establish appropriate safety warning mechanism for early warning of disaster that may occur, real-time monitoring and diagnosis of structural performance of key projects play a critical scientific role in improving the safety and reliability of the structure. It also can reduce operating and maintenance costs of the structure, with considerable economic value. Real-time monitoring of the health of the structure and to assess its safety has become an inevitable requirement for the construction of the future. It is also an important issue to be solved in the 21st century. In this paper, a kind of large range FBG strain sensor has been developed to meet the needs that a number of civil engineering structures working under the conditions of large stress and strain actually. Calibration experiment and applications of the new sensors are accomplished to gain its measurement accuracy and error range.In this paper, technological innovation has been done based on the existing principle of fiber grating strain sensors. The basic theory of the large range fiber grating strain sensors is established. A new type package of sensor is designed under the guidance of the basic theory. Compared with the previous FBG strain sensor, this new sensor can pass the response from the tested components to the grating after weakened into a multiple through the sensor which guarantying the strain of FBG withstanding do not exceed the ultimate tensile strain. It also increases the measurement strain range of the sensor. The reason there is a deviation between the actual package sensor parameters and design values is analyzed. And the actual test range and accuracy of the sensor is calibrated.This new fiber grating sensors are small, simple structure, good stability and reliability, ease of installation, with all the advantages of FBG sensors. Different forms of sensor holders can be used on tested components of different shapes so that the sensor can monitor the stress state of the member effectively. In this paper, the large range fiber grating sensors are attached to the surface of the prestressed steel strand successfully and monitor the tensioning process stress state of the strand effectively. Unlike ordinary steel, sensor cannot be welded on it. An curved support is designed for that large range fiber grating strain sensors can be mounted on the strand easily. The relationship between strain measured by the sensor and actual values is analyzed combined force forms of the strand. Method is proposed to correct bias.The main concrete structure of Shenyang City Cultural Arts Center was monitored during its construction phase by task force members using fiber grating concrete strain sensors and temperature sensors. Some problems existing in engineering applications of FBG sensors are solved in the monitoring process and good monitoring results are achieved. It provides a valuable basis for Construction Quality Control and Construction Safety.