A Stress and Strain Monitoring Method for Bridge Cantilever Construction Based on Fiber Bragg Grating Sensing Technology

In view of the shortcomings of traditional monitoring techniques for internal stress and strain in bridges, such as poor durability and cumbersome measurement, a structural health monitoring method of bridge hanging basket construction based on fiber grating sensing technology was proposed. Taking the cross-Changhe expressway separation interchange bridge as the research case, the most unfavorable cross section of the bridge under live load during construction was selected, and optical fiber sensors were implanted at the intersection points of the top plate, bottom plate and web center line of the initial girder section at the bridge pier to monitor its stress and strain. The stress and strain changes of the starting beam section during the construction period of the hanging basket were analyzed. Evaluate the internal structural health status of bridge hanging basket during construction period. The results show that the increase of stress and strain in the roof of the initial beam section is mainly affected by the prestress and tension, and that of the bottom plate is mainly affected by the concrete pouring. After the box girder of the middle span closed section is poured, the middle span beam section no longer presents the phenomenon of pulling up and pressing down. The roof stress reaches its peak value after prestressing the beam section in front of the edge span closing section, and the floor stress reaches its peak value after pouring the beam section in front of the edge span closing section. The roof strain reaches its peak value after prestressing the beam section before the side span closing section, and the floor strain reaches its peak value after prestressing the side span closing section. During the construction of bridge hanging basket, the stress and strain changes from the construction of the beam section before the side span is closed to the end of the construction should be emphasized.