Daiki MATSUMOTO
Fundamental Study on CFRP Strand Sensor Realizing Repair and Condition Evaluation of Steel Structure
Takeshi MIYASHITA
Carbon Fiber Reinforced Polymer (CFRP) has outstanding characteristics such as light weight, high strength and high elasticity. Therefore, CFRP sheet has begun to been applied to repair or reinforcement for steel structures. However, there is a problem that it is impossible to evaluate the state of adherents or adhesive after CFRP sheet is bonded on the surface of a structure. To overcome this problem, electrical conductivity of carbon fiber is focused on. By measuring change of the electrical resistance, it is expected as an intelligent material that has self-diagnostic functions such as detection of delamination. Herein, CFRP strand sheet, which consists of independent carbon fiber strand, is utilized. This sheet has possibility to realize both repair and evaluation of local conditions together.
Firstly, in order to find appropriate CFRP sheet for sensor, fundamental material test was carried out for various CFRP strand sheets. Through uniaxial tensile tests it was confirmed that electrical resistance increased as applied load increased. Among various CFRP sheets, middle elastic type CFRP sheet, which was one of PAN type CFRP sheet, showed good linearity between load and electrical resistance. Then, in order to evaluate the performance of selected CFRP sheet as sensor, the sheet was bonded on a steel plate, which was cut only one side from the center in the plate width direction. The length, width and thickness of the steel plate are 1000 mm, 60 mm and 9 mm respectively. Moreover, strain gauges were installed on the surface of CFRP sheet for verification. As a result, when axial load on the plate increased, electrical resistance in only one side of CFRP sheet also increased. This reveals that the proposed idea has feasibility.
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