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Fatigue evaluation and CFRP strengthening of diaphragm cutouts in orthotropic steel decks
Lu Ke,Chuanxi Li,Jun He,Yongjun Lu,Yang Jiao,Yongming Liu 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.4
The cracking at the transverse diaphragm cutout is one of the most severe fatigue failures threatening orthotropic steel decks (OSDs), whose mechanisms and crack treatment techniques have not been fully studied. In this paper, full-scale experiments were first performed to investigate the fatigue performance of polished cutouts involving the effect of an artificial geometrical defect. Following this, comparative experimental testing for defective cutouts strengthened with carbon fiber-reinforced polymer (CFRP) was carried out. Numerical finite element analysis was also performed to verify and explain the experimental observations. Results show that the combinative effect of the wheel load and thermal residual stress constitutes the external driving force for the fatigue cracking of the cutout. Initial geometrical defects are confirmed as a critical factor affecting the fatigue cracking. The principal stress 6 mm away from the free edge of the cutout can be adopted as the nominal stress of the cutout during fatigue evaluation, and the fatigue resistance of polished cutouts is higher than Grade A in AASHTO specification. The bonded CFRP system is highly effective in extending the fatigue life of the defective cutouts. The present study provides some new insights into the fatigue evaluation and repair of OSDs.
Lei Zhang,Lulu Guo,Jingna Ding,Yongming Lu,Yaping Zhang,Yan Chen 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.8
In order to develop the application of the natural polysaccharide lentinan (LNT) and decrease the side effects of doxorubicin, we successfully synthesized a novel folate-modified maleilated lentinan-doxorubicin (FA-M.LNT-DOX) polymer and used it for tumor-targeted drug delivery. The release efficiency and cytotoxicity of the prodrugs were evaluated in vitro. Although DOX release from FA-M.LNT-DOX was quite slow in a neutral buffer, it was particularly fast in an acidic solution with a pH of 5.0. Compared with DOX, FA-M.LNT-DOX showed higher cytotoxicity in HeLa cells and significantly lower cytotoxicity in normal cells. These results suggested that FA-M.LNT-DOX could be considered as a potential drug delivery candidate for folate receptor-positive cancer therapy.