Abstract
Carbon fiber reinforced polymers (CFRP) have shown considerable potential in the repair and rehabilitation of deficient reinforced concrete (RC) structures. To date, several CFRP strengthening schemes have been studied and employed practically. In particular, strengthening of shear damaged RC members with CFRP materials has received much attention as an effective repair and strengthening approach. Most existing studies on strengthening shear-deficient RC members have used unidirectional CFRP strips. Recent studies on strengthened T-beams demonstrated that a bidirectional CFRP layout was more effective than a unidirectional layout. As such studies are limited, in this study, the feasibility of bidirectional CFRP layouts for the shear strengthening of rectangular RC beams was experimentally evaluated. Bidirectional layout details with CFRP anchors as well as rehabilitation timing were considered and investigated. The test results showed that the members with a bidirectional CFRP layout carried less shear strength capacity than those with unidirectional layouts for the same quantity of CFRP material. Nevertheless, the bidirectional CFRP layout allowed for a uniformly distributed stirrup strain compared to the unidirectional CFRP layout at the same load level, which increased the efficiency of the transverse reinforcement. Additionally, the shear contribution of CFRP material according to the CFRP strengthening timing was verified.
Highlights
Aging reinforced concrete (RC) structures undergo strength deterioration owing to extreme environmental and loading effects
The results showed that the use of anchored unidirectional carbon fiber-reinforced polymers (FRP) (CFRP) could increase the shear capacity slightly (2%), while a significant increase in shear capacity was observed in members with bidirectional
Alotaibi [25] tested eight shear-strengthened RC T-beam sections similar to typical bridge girders with anchored bidirectional CFRP strips to investigate their behavior and make a direct comparison with the results reported by Kim et al [14]
Summary
Aging reinforced concrete (RC) structures undergo strength deterioration owing to extreme environmental and loading effects. Alotaibi [25] tested eight shear-strengthened RC T-beam sections similar to typical bridge girders with anchored bidirectional CFRP strips to investigate their behavior and make a direct comparison with the results reported by Kim et al [14]. The concrete and CFRP shear contributions showed an interaction, whereas the contribution of the internal shear reinforcement was found to be identical to its contribution in the case of non-strengthened RC beams These tests were the first of their kind and provided very useful technical information on the behavior of bidirectional CFRP strengthened beams under shear. These tests are limited in number and were carried out on the T-sections, and the results may not necessarily be true for members with rectangular sections. A total of 18 RC beams were constructed and tested to evaluate various CFRP strengthening features such as the strengthening timing, presence of CFRP anchors, CFRP layouts, etc
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