Strain data correction of distributed optical fiber sensors using strain transfer model with variable shear lag parameters

Distributed optical fiber sensing techniques have been widely utilized in the field of structural health monitoring (SHM) of civil structures. However, strain measurements from distributed optical fiber sensors cannot always accurately reflect the strain of the host material of structures due to the coupled effects of the composite protective layer of the cables and the quality of the surface bonding construction. To address this issue, a method is proposed for correcting the strain data for civil structures measured by surface bonded distributed optical fiber sensors. The layered analysis method is used to establish a strain transfer model from the fiber core, through the inner protective layer, rigid protective layer, outer protective layer, and adhesive layer to the host material of the structure. With the new method, the strain transfer coefficient from the fiber core to the host material of the structures is calculated by updating the shear lag parameters based on a finite element model with a specific bonding length. The results of an experimental model and an actual bridge show that, comparing with the current methods, the proposed method effectively improves the accuracy of strain data from the distributed optical fiber sensors. The proposed method is benefit for the application of distributed optical fiber sensing techniques in monitoring the condition of actual civil structures. •A method is proposed to correct strain data from surface bonded distributed optical fiber sensors.•A strain transfer model from fiber core to host material of structure is established.•Strain transfer coefficient is calculated by updating shear lag parameters.•Accuracy of strain data from the distributed optical fiber sensors is improved compared to the state-of-the-art.