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ABS Tabatabaei

One of the methods of retrofitting reinforced concrete structures is use of FRP sheets to increase the flexural and shear strength of concrete elements. Use of FRP materials is in rapid progress because of their high strength, light weight and easy installation of FRP composites. Poisson’s ratio mismatch between FRP sheets and concrete is resulted premature debonding of FRP strips. Surface preparation for being connected to the sheets can delay debonding to some extent. This separation, however, has been evidenced in most studies in reinforcement concrete beams have been strengthened by FRP sheets. On the other hand, preparing the surface of concrete suffers from such limitations as losses due to pause in work, expensiveness, and even lack of access to the member involved. Therefore, in the current study, the effect of preparing the surface for shearing strength of reinforcement concrete beams and replacement of this method by grooving will be investigated.

The experimental specimen included 20 beams of 560×85×80 mm and 48 beams of 560×85×70 mm and covered 11 series subjected to four-point loading. An attempt was made to delay flexural failure of beams through longitudinal and mechanical anchorages so that it would be possible to compare the increase in the shearing capacity of the beams resulting from the use of different methods in installing FRP strips. The beams used in each series include control beams, the strengthened without surface preparation, with surface preparation and with grooving method. The results of the study showed that surface preparation before installation of FRP strips can increase failure load to a small extent when compared with specimen without surface preparation. However, the debonding of FRP strip from concrete surface still occurs. This method, increases shear capacity, and can also increase ultimate load of beams up to 12 percent.   On the other hand, Comparison between the ultimate load and deflection of the test beams demonstrates that grooving method was effective and led to elimination of debonding of FRP strips used for shear strengthening. This method, increases mid span deflection, and also increase ultimate load of beams up to 19 percent.  

  

تحت نظارت وف ایرانی

ABS Tabatabaei | Davood Mostofinejad, Ph.D., PE

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تحت نظارت وف ایرانی