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This paper presents the results of an experimental and analytical study of the fatigue performance of reinforced concrete beams strengthened with externally post-tensioned carbon-fibre-reinforced polymer (CFRP) tendons. Two loading conditions prior to strengthening the beams were investigated: in-service loading and overloading. A total of 18 beams were tested to failure: three under monotonic loading and fifteen under fatigue loads. The CFRP tendons were post-tensioned to 40% of their ultimate capacity. The results demonstrated that overloading the beams had no discernable effect on the fatigue life of the strengthened beams. The strain-reduction approach for unbonded steel tendons was modified to account for using CFRP tendons and for the permanent deformations resulting from the overloading process. The loading history of the beams prior to and after post-tensioning was incorporated into a strain-life fatigue model to predict the fatigue life of the strengthened beams. Key words: concrete beams, overloading, damage, post-tensioning, fatigue, fiber-reinforced polymer, strain life. Cet article presente les resultats d'une etude experimentale et analytique de la resistance a la fatigue de poutres en beton arme renforcees d'une armature externe post tensionnee en polymeres renforces de fibres de carbone (<< PRFC >>). Deux conditions de chargement avant le renforcement des poutres ont ete examinees : en service et en surcharge. Dix-huit poutres ont ete mises a l'epreuve jusqu'a defaillance, trois sous un chargement monotone et 15 sous des charges de fati gue. Les armatures en << PRFC >> ont ete post tensionnees a 40 % de leur capacite maximale. Les resultats ont montre que la surcharge des poutres n'avait aucun effet evident sur la duree de vie en fatigue des poutres renforcees. L'approche de reduction des contraintes pour les armatures en acier non adherentes a ete modifiee pour tenir compte de l'utilisation d'armatures en << PRFC >> et des deformations permanentes decoulant du processus de surcharge. L'historique des chargements des poutres avant et apres le post-tensionnement a ete incorpore dans un modele de fatigue contrainte-duree de vie afin de predire la duree de vie en fatigue des poutres renforcees. Mots-cles : poutres en beton, surcharge, dommage, post-tensionnement, fatigue, polymere renforce de fibres, contrainteduree de vie. [Traduit par la Redaction], Introduction and background Strengthening of reinforced concrete structures can be achieved by various techniques, usually governed by the type of the structure and its functionality. External posttensioning is a proven [...]

We studied the magnetization (M-H) curve of immobilized magnetic nanoparticles (MNPs) used for biomedical applications. First, we performed numerical simulation on the DC M-H curve over a wide range of MNPs parameters. Based on the simulation results, we obtained an empirical expression for DC M-H curve. The empirical expression was compared with the measured M-H curves of various MNP samples, and quantitative agreements were obtained between them. We can also estimate the basic parameters of MNP from the comparison. Therefore, the empirical expression is useful for analyzing the M-H curve of immobilized MNPs for specific biomedical applications. [ABSTRACT FROM AUTHOR]