PSI - Issue 64

Muhammad Ishfaq et al. / Procedia Structural Integrity 64 (2024) 1540–1548 Ishfaq et al./ Structural Integrity Procedia 00 (2024) 000 – 000

1547

8

0 1000 2000 3000 4000 5000 6000 7000 8000

Individual U-wrap strains Mean Effective U-wrap strain per ACI 440.2 Maximum permitted U-wrap Strain per ACI 440.2

Strain in U-wraps (  )

Shear Control

Flexure Control

1U 2U 1U 2U 1U 2U no stirrups #2@200 #4@200

Fig. 6. Peak U-wrap strains recorded at ultimate load (two U-wrap strains were considered in shear control specimens as being engaged in the shear failure plane). 4. Conclusions The data presented in this paper are part of an ongoing experimental study. The results presented are based on 12 tested specimens, while an additional six specimens remain to be tested. The following are, therefore, preliminary conclusions: 1. U-wraps increased the shear strength by 47% to 76% in shear-critical beams (Groups A and B); however, the shear contribution of U-wraps decreased by 20% to 30% with an increase in internal steel shear reinforcement ratio from 0% to 0.1%. 2. In flexure-controlled specimens (Group C), the strain in the longitudinal CFRP sheet increased by up to 56% compared to the unanchored strengthened specimen and 118% compared to the ACI 440.2-prescribed debonding strain [for unanchored FRP]. This resulted in a corresponding moment capacity increase of 27%. 3. The experimental strain values in both longitudinal CFRP sheets and U-wraps were higher than the strain values predicted by ACI 440.2 equations, validating the [expected] conservative nature of these equations. 4. The failure in the flexural-controlled specimens strengthened with U-wraps was ductile (compared to the unanchored strengthened beam), with extensive yielding of tension steel prior to the rupture of the U-wraps or U-wraps debonding and concrete crushing. Acknowledgements Authors gratefully acknowledge funding provided under the subaward no. 5903-UD-DOT-7103 to the University of Delaware by the United States Department of Transportation — Center for Integrated Asset Management for Multimodal Transportation Infrastructure Systems at the Pennsylvania State University (Federal Grant No. 69A3551847103). Authors thank Simpson Strong-Tie Co., LLC for supplying the materials, providing installation, and funds.