Deformation monitoring of cracked concrete structures based on distributed optical fiber sensing technology

In recent years, distributed fiber optic sensing (DFOS) has been widely used for structural deformation monitoring. Conventional deformation monitoring methods using DFOS have a limitation in that they are based on the conventional assumptions in continuum mechanics such as uniformity and continuity. These methods are unsuitable for cracked concrete structures that exhibit discontinuity (discrete body). This paper proposes an advanced neural network method that can accurately measure the deformation of cracked concrete structures. The basic principle of the method is introduced, and its performance is validated by conducting a concrete beam loading test. Subsequently, the deformation calculation results obtained using the proposed method are compared with those obtained using the conventional conjugate beam method. The two methods could accurately estimate the deformation of the concrete beam before crack formation. The proposed neural network method could accurately determine the deformation with a maximum error of only 4.3% at all loading levels even after crack formation, whereas the conventional method exhibited a maximum error of 33.6% in this stage. The test results confirm the advantages of the proposed method in making accurate estimations of the deformation in concrete structures with cracks.