Experimental Investigation of Shear Strength of Reinforced Concrete Beams Externally Strengthened by CFRP
No Thumbnail Available
Files
Date
2021-12-13
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Numerous types of structures have been retrofitted and rehabilitated using carbon fiber reinforced polymer (CFRP) composites. The common method of strengthening is Externally Bonded Reinforcement (EBR), however this method has a main problem which is debonding issue. Recently, alternative methods were presented to delay or eliminate the deboning issue such as Externally Bonded Reinforcement on Groove (EBROG). In this study, ten reinforced concrete (RC) beams with dimensions of 1200 mm in length, 170 mm in depth and 120 mm in width were investigated. One beam was un-strengthened (reference beam) and nine beams were strengthened with CFRP sheets against shear and tested under four-point loading. Three strengthening techniques have been considered in this research; EBR, EBR with longitudinal anchoring (center or upper and lower anchoring) and Externally Bonded Reinforcement on Grooves (EBROG). Three beams strengthened by EBR method, two of those beams with CFRP sheet anchorage. The remaining six beams were strengthened by grooving method. Number of layers, grooves shape and surface preparation are considered as variables of this study. The test results indicated that EBROG strengthening technique leads to improve the shear capacity in comparison with EBR method. Besides, test results demonstrate that EBROG method performed better than EBR; as a result, debonding of CFRP sheet are eliminated for all beam specimens strengthened by EBROG technique. Two layers of CFRP and vertical and horizontal grooves comparing to the vertical groove attained a little additional gain in shear capacity for strengthening beams. The improving in shear capacity for beam strengthened by EBR was 2%, while the improving in the capacities of beam specimens strengthened by EBR method with anchoring ranged from
IV
13% to 25%. In addition, EBROG method improved the capacities of the beams by 12% to 28% comparing to the un-strengthened beam. The results of some of the available design codes and guidelines for calculating the CFRP contribution to the shear strength were presented. It was observed that the predicted results obtained from ACI-440.2R- 17 and Chen model- 2010 match well with the experimental results while the predicted results obtained from CNR-DT 200 R1, Fib Bulletin 14, Chen model -2003 and Dias and Barros model were overestimated