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For the high strength, corrosion resistance, and good stability, carbon fiber–reinforced polymer (CFRP) composites have been made into pipes to transfer gasses and oils in subsea environment. Structural performance of CFRP composite pipes is particularly important to sustain the regular operation of the delivery system. To obtain the in-field behavior of the CFRP composite pipes, quasi-distributed optical fiber sensing techniques are developed based on the multiple configuration of fiber Bragg grating (FBG) sensing elements. Theoretical investigation on the dynamic response of the pipes is performed. Experiments on cantilever CFRP pipes with surface-attached FBGs in series and packaged FBG sensors have been conducted to check the feasibility and effectiveness of the proposed sensing technique. Results validate the good measurement performance of the proposed sensors and the accuracy of the vibration analysis. The study can be adopted to instruct the establishment of the structural health monitoring system of CFRP composite pipes and assess the safety operation state of the pipe systems.

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Carbon fiber reinforced polymer (CFRP) composites have been extensively used in airframes, train bodies, and engine blades for their properties of high strength, low weight, and good stability. The in-service structural performance of CFRP composites is always an important point to be investigated for its influence on structural safety. For this reason, CFRP composite plates assembled with fiber Bragg grating (FBG) sensors were developed, and the in-service structural characteristics of the CFRP plates were interpreted by FBG signals measured through time. A theoretical analysis supported by a numerical method has been provided. Experimental testing was conducted to check the proposed sensing technique for the dynamic response identification of the CFRP plate. The curing process of the bilayer CFRP plated inserted with FBGs in series was also explored. The results showed that the surface-attached FBGs in series could accurately characterize the dynamic response of the CFRP plate, and a good agreement between the numerical and testing results was observed. The strain and temperature distributions during the curing process of the bilayer plate indicated that the in-service structural performance of bilayer CFRP plates can be configured by the assembled FBG sensors. This study can support the structural health monitoring of projects by using CFRP composites.

Interfacial performance is quite significant for maintaining the structural performance of steel–concrete composite structures. Quantitative assessment on the interfacial effect is critical. For this reason, theoretical investigation on the interfacial interaction of steel–concrete composites was performed, with the symmetry of the model considered. Influence of interfacial slip on the mechanical properties of the composites was considered. Analytical solutions of the interfacial slip and strain were provided. The accuracy of the predictions from the improved analytical model was validated by comparing them against the results from experimental and numerical studies. The influence of design parameters of the composite members on the interfacial effect was discussed. The proposed analytical model was also employed to assess the effect of the bond developing at the interface between concrete and steel on the deformation exhibited by simple composite structural forms (e.g., beams). Through the analysis, the priority design parameters of the composite structures are determined for controlling the level of interfacial slip in order to achieve optimum bearing capacity. Different to commonly used energy methods, numerical methods and finite element methods, the study provides a simple and straightforward analytical solution for describing the interfacial interaction of composite structures for the first time, which can act as scientific instruction for the interfacial slip control of composite materials and structures.