To obtain a measuring method in which the strain of a test member can be measured irrespective of the generation of a crack, by a method wherein an optical fiber is fixed to the surface of the test member via a shock absorbing member whose yield stress is higher than that of the test member and whose modulus of elasticity is smaller than that of the optical fiber.
Optical fibers 2 which are covered with nylon through a measuring apparatus B-OTDR 8 for a strain distribution are pasted in the center on the surface and in the center on the rear surface of a beam 1 via urethane resins, as shock absorbing members, whose yield stress is higher than that of concrete as the beam 1 and whose modulus of elasticity is smaller than that of the optical fibers 2. Accordingly, even when a crack is generated in the beam 1, the optical fibers 2 are not torn into pieces, and the strain distribution on the surface of the beam 1 can be measured easily. At this time, a strain measured value before the generation of the crack is precise, and the value of a strain in every position is increased rectlinearly due to an increase in a load after the generation of the crack. Consequently, when, after the generation of the crack, the strain measured value of the optical fibers 2 is proportionally calculated, the value of the strain which is generated actually can be found.
NOBIKI ATSUSHI
KURASHIMA TOSHIO
NARUSE HIROSHI
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