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Structural Monitoring and Maintenance
  Volume 6, Number 4, December 2019, pages 291-315
open access

An overview of different retrofitting methods for arresting cracks in steel structures
Mohammad Karamloo, Moosa Mazloom and Ali Ghasemi

    Fatigue cracks are inevitable in circumstances in which the cyclic loading exists. Therefore, many of mechanical components are in a risk of being in exposure to fatigue cracks. On the other hand, renewing the facilities or infrastructures is not always possible. Therefore, retrofitting the structures by means of the available methods, such as crack arrest methods is logical and in some cases inevitable. In this regard, this paper considers three popular crack arrest methods (e.g., drilling stop-hole, steel welded patch, and carbon fiber reinforced (CFRP) patch), which have been compared by using extended finite element method (XFEM). In addition, effects in terms of the width and thickness of patches and the configuration of drilling stop holes have been evaluated. Test results indicated that among the considered methods, CFRP patches were the most effective means for arresting cracks. Besides, in the case of arresting by means of drilling stop holes, drilling two holes next to the crack-tip was more effective than blunting the crack-tip by drilling one hole. In other words, the results indicated that the use of symmetric welded metal patches could lead to a 21% increase in fatigue life, as compared to symmetric stop holes. Symmetric CFRP patches enhanced the fatigue life of cracked specimen up to 77%, as compared to drilling symmetric stop holes. In addition, in all cases, symmetric configurations were far better than asymmetric ones.
Key Words
    fatigue crack; CFRP and steel patch; crack arrest; stop-hole; retrofit
Mohammad Karamloo, Moosa Mazloom and Ali Ghasemi: Department of Civil Engineering, Shahid Rajaee Teacher Training University, Lavizan, Tehran, Iran

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