Analytical Evaluation of RC Beams Strengthened with Near Surface Mounted CFRP Laminates


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Title: Analytical Evaluation of RC Beams Strengthened with Near Surface Mounted CFRP Laminates

Author(s): J.-Y. Kang, Y.-H. Park, J.-S. Park, Y.-J. You, and W.-T. Jung

Publication: Special Publication

Volume: 230


Appears on pages(s): 779-794

Keywords: carbon fiber reinforced polymer (CFRP); groove depth; near surface mounted (NSM); spacing; strengthening

Date: 10/1/2005

To assess the strengthening efficiency of near-surface mounted (NSM)carbon fiber reinforced polymer (CFRP) laminates according to their groove depth anddisposition, 4-point bending tests were performed on 4 specimens strengthened withNSM CFRP. A structural model for the finite element method (FEM) able to simulateaccurately the experimental results was determined to analyze the strengtheningefficiency of the NSM technique analytically. Applying the model, parametric analysiswas performed considering the groove depth and spacing of CFRP laminates. Analyticalstudy on the groove depth revealed the existence of a critical depth beyond which theincrease of the ultimate load becomes imperceptible. In other words, this means thatthere exists a limit of strengthening efficiency where it remains in a definite level evenif the groove depth is increased. Analytical results regard to the spacing of the CFRPlaminates showed that comparatively smooth fluctuations of the ultimate load wereproduced by the variation of the spacing and the presence of an optimal spacing rangefor which relatively better strengthening efficiency can be obtained. Particularly, aspacing preventing the interference between adjacent CFRP laminates and theinfluence of the concrete cover at the edges as well as allowing the CFRP laminates tobehave independently was derived. Using the analytical results, various strengtheningschemes could be established with different numbers of CFRP laminates, groove depthsand dispositions of the reinforcements for a determinate quantity of reinforcements.