Packaged optical fiber Bragg grating（FBG） strain gauge with good properties of high durability

low cost and reliable installation is in the great need of practical long-term structural health monitoring（SHM） system for civil infrastructures

especially for those under harsh construction and service environment

such as corrosion

high fatigue

etc.Aiming at the practical applications of FBG in such areas

a novel kind of prototype-packaged FBG gauge for steel rebar is developed.And its sensing properties under dead load are tested.The results from experiments and theoretical analyses show that they are consistent with each other

the wavelength changes are linear with the strain and the correlation coefficient is above 0.999.After contrasting the strain inside and outside the tube

it is clear that the steel bar gauge for FBG can reflect the steel strain accurately.