Title:
Effect of Bond Condition on Cyclic Behavior of Post- Tensioned Concrete Beams with Carbon Fiber-Reinforced Polymer Tendons
Author(s):
Fei Peng, Weichen Xue, and Shulu Zhang
Publication:
Structural Journal
Volume:
121
Issue:
2
Appears on pages(s):
153-163
Keywords:
carbon fiber-reinforced polymer (CFRP); cyclic behavior; ductility; partially bonded; prestressed concrete beam
DOI:
10.14359/51740251
Date:
3/1/2024
Abstract:
The lack of ductility is the main concern in the use of carbon
fiber-reinforced polymer (CFRP) reinforcement as prestressing
tendon in concrete members. To address this concern, a partially
bonded concept has been proposed. In this approach, CFRP
tendons are intentionally debonded from the concrete in the middle
region of the prestressed concrete beam, while remaining bonded
at each end. In this study, eight post-tensioned beams, including
five beams with CFRP tendons and three beams with steel tendons,
are tested under cyclic loading. Three bond conditions, including
fully bonded, partially bonded, and fully unbonded, are considered.
The results indicate that increasing the unbonded length of the
tendon changed the failure mode from CFRP rupture to concrete
crushing. There is a trend that the flexural capacity decreased with
the increase of the unbonded length. The displacement ductility
(μ) of partially bonded CFRP prestressed beams ranged from 5.38
to 5.70, which is significantly higher than that of the fully bonded
beam (μ = 2.83) and slightly lower than that of the fully unbonded
beam (μ = 6.10). Finally, by introducing a relative bond length
coefficient into the ultimate tensile stress equation for internally
unbonded tendons, a modified design approach for estimating
flexural capacities of the partially bonded beams is proposed. The
experimental flexural capacities are in close agreement with the
values predicted using the modified design approach.