The stress state of anchor bolt changes because of the weathering of anchoring structure

the stress of the bolt itself

the creep deformation will change stress state of bolt. In order to real-time reflect stress state of stress state of anchor bolt

the fiber Bragg grating strain sensor is welded to the bolt body by pin in an axial direction. The pin distance of fiber Bragg grating strain sensor changes by the stress of the bolt

which makes the fiber Bragg grating center wavelength occur shift inside strain sensor. Through displacement measurement of the fiber Bragg grating center wavelength

on-line monitoring of anchor bolt’s axial tension can be realized. Tension tests of anchor bolt indicate that the sensitivity is 6. 5 pm / kN

and the nonlinearity error is 1. 78 % FS.