Li He

Carbon fibre-reinforced polymer (CFRP) bonded steel structures are increasingly adopted in offshore floating structures, yet their interfacial performance is highly susceptible to corrosion in marine environments. Corrosion-induced degradation of the CFRP–steel interface can significantly affect load transfer mechanisms and long-term structural reliability. This paper reports an experimental study on corrosion-induced degradation mechanisms and bond–slip behaviour of CFRP–steel double-strap joints. Controlled corrosion damage was generated using an accelerated electrochemical technique calibrated to ISO 9223 corrosivity categories. Tension tests were performed to examine the effects of corrosion degree, CFRP bond length, and the inclusion of glass fibre sheets (GFS) in the adhesive layer on failure modes, ultimate load capacity, and effective bond length. Digital image correlation (DIC) was employed to obtain strain distributions along the CFRP plates and to establish a bond–slip model for corroded interfaces. The results indicate that corrosion promotes a transition from CFRP delamination to steel–adhesive interface debonding, reduces interfacial shear strength to 17.52 MPa and fracture energy to 5.49 N/mm, and increases the effective bond length to 130 mm. Incorporating GFS mitigates corrosion-induced bond degradation and enhances joint performance. The proposed bond–slip model provides a basis for more reliable durability assessment and design of bonded joints in corrosive environments.

Photocatalytic oxidation technology holds considerable promise for effectively removing volatile organic compounds. However, conventional gas-solid photocatalytic technology is hindered by limitations, notably a low mineralization rate. This study introduces an innovative gas-liquid-solid photocatalytic oxidation system that utilizes a superhydrophilic/superhydrophobic photocatalyst for the efficient removal of methyl mercaptan. By synthesizing superhydrophobic Cu-doped UiO-66 and combining with TiO2, the resulting OCUN/T photocatalysts was thoroughly chatacterized and tested under various conditions. The system consistently maintains a high removal rate (exceeding 77.5%) and a substantial mineralization rate of methyl mercaptan over 10 hours operation. Remarkably, the removal efficiency of methyl mercaptan can reach up to 70.14% at sunlight intensities exceeding 35×1000 lm. Additionally, a detailed mechanism for the degradation of methyl mercaptan via the gas-liquid-solid photocatalytic oxidation system is proposed, presenting a novel and cost-effective method for the VOCs removal.

Stability has been an important subject in the design of a portal frame structure. Conventional stability analysis of the portal frame is normally conducted assuming that all the joints are rigid. However, the joints of a portal frame in real applications are not always rigid and semirigid connections often exist. AISC design code requires that the effect of the joint flexibility on the behavior and buckling capacity of the portal frame should be taken into account in the analysis and design procedures. To address this issue, a portal frame with flexible joints and rigid members was theoretically analyzed in the literature and closed form solution was derived for its global buckling load. However, when more parameters are involved, e.g., different leg lengths, asymmetric frame shape, and moving load, the solution to the governing equation of the stability of the frame becomes impossible. This paper presents a comprehensive parametric study on the stability of an asymmetric portal frame with flexible joints and rigid members through finite element (FE) analysis. The FE model was first validated by the existing theoretical solution in the literature. Parameters including the position of the moving load, the lengths of the two frame legs, and the span of the frame were analyzed. Design curves were developed based on the parametric study, from which the stable, unstable, and catastrophically unstable states of the portal frame were characterized. This paper contributes benchmark results for the stability optimization in the design of the portable frame of a general shape.