Study On The Application Of Fiber Grating Sensing Technique To Health Detection For Space Truss

With the development of the theory of spatial structures, computer technology and the new construction technology, spatial structures are applied to a good many domains. Space truss has good mechanical performance and can be manufactured and constructed conveniently, it is the structure system which develops most rapidly and is applied most extensively among all spatial structures.First, the development of spatial structures and the extensive application in a great deal domain of space truss were introduced. Space truss is usually long-span and complicated structure. During these years, the accidents about space truss happened from time to time. Health detection has been the hot topic among many domains. In order to protect the safety of the life and the property of people, health detection and safety assessment for long-span space truss has been an important research subject at present and in future.The technique of health detection at present was analyzed systematically. A practical strategy of health detection for space truss was proposed and the corresponding flow chart of detection was designed.The advantages and disadvantages and performance of all kind of intellectual sensors were analyzed and compared systematically, and the fiber grating was selected as the sensor of health detection for space truss. The advantages of fiber grating over the resistance fragment was analyzed. According to the traits of space truss and the requirement for convenient field installation in practical engineering structures, a new installation technique of fiber grating was proposed and the corresponding clamp devices were designed which can be installed and uninstalled quickly. This installation technique is non-destructive to steel tubes and does not produce residual stress and the fiber grating sensors can be used repeatedly. Then, the health detection system of space truss non-destructive to steel tubes based on fiber grating which can be installed and uninstalled quickly was proposed.In order to prove theoretically the feasibility and applicability of the detection device and system to members of space truss, the relationship of the strain change of members of space truss and the wavelength change of fiber grating was derived in detail, so do the relationship of the change of internal force and the wavelength change.In order to verify the applicability of the detection device and system to steel tubes, and analyse the reliability about the transfer of strain and internal force and the measure precision, the tension and compression experiment was carried out.The health detection strategy and system proposed were applied to a space truss structure on service to verify their feasibility and practicability and understand the health situation of the detected region in this space truss.