Effect of Steel Stirrups on Shear Resistance Gain Due to Externally Bonded Fiber-Reinforced Polymer Strips and Sheets

This paper presents the results of an experimental investigation of reinforced concrete (RC) T-beams strengthened in shear with externally bonded (EB) carbon-fiber-reinforced polymer (CFRP) strips and sheets. The main objective of this study was to gain insight, by varying the test parameters, into the interaction between the internal transverse-steel reinforcement and the externally bonded CFRP used for strengthening of RC beams in shear. The test parameters of this study were: 1) the CFRP ratio (i.e., the spacing of the CFRP strips); 2) the presence or absence of transverse steel; 3) the transverse-steel ratio (that is, the spacing of the stirrups); and 4) the use of CFRP strips versus CFRP sheets. In total, 10 tests were performed on 4520-mmlong (14 feet and 10 inches) T-beams. The study showed that the presence of internal transversesteel reinforcement resulted in a significant decrease in the gain due to CFRP for all the strengthened specimens. It also showed that the steel yielded before failure for all the test