Design model for the intermediate crack induced debonding (IC debonding)
in RC beams strengthened with FRP plates is proposed based on FE
results. This model is better than any existing models comparing
with a lot of test results.
G. Teng of the Hong Kong Polytechnic University. Prof.
L. P. Ye and J. J. Jiang of Tsinghua University
Models for the Debonding Strength of RC Beams Strengthened with
Building Structures, 2007. 37(12): 79-82.
The FRP-to-concrete interfacial debonding is a fundamental key problem
for the strengthening of RC structures with externally bonded FRP
sheets/plates. This paper presents the design models and detail
designs on the flexural or shear debonding of RC beams strengthened
with FRP sheets/plates, which is based on the latest experimental
and theoretical researches on the FRP-to-concrete interfacial constitutive
behavior, flexural and shear strengthening.
Keywords: FRP sheets/plates, strengthening, debonding, interface.
crack debonding in FRP-strengthened RC beams: FE analysis and strength
Journal of Composite for Construction, ASCE, 11(2),
Reinforced concrete (RC) beams strengthened in flexure with a bonded
fiber-reinforced polymer (FRP) plate may fail by intermediate crack
(IC) debonding, in which debonding initiates at a critical section
in the high moment region and propagates to a plate end. This paper
first presents a finite-element (FE) model based on the smeared
crack approach for concrete for the numerical simulation of the
IC debonding process. This finite-element model includes two novel
features: (1) the interfacial behavior within the major flexural
crack zone is differentiated from that outside this zone and (2)
the effect of local slip concentrations near a flexural crack is
captured using a dual local debonding criterion. The FE model is
shown to be accurate through comparisons with the results of 42
beam tests. The paper also presents an accurate and simple strength
model based on interfacial shear stress distributions from finite-element
analyses. The new strength model is shown to be accurate through
comparisons with the test results of 77 beams, including the 42
beams used in verifying the FE model, and is suitable for direct
use in design.
proposals for the debonding strengths of FRP strengthened RC beams
in the Chinese design code
International Symposium on Bond Behaviour of FRP in Structures (BBFS
2005), Hong Kong, China, 2005. 45-54.
ABSTRACT: Debonding failures
are very common in FRP strengthened RC structures so they must be
carefully considered in design. In the last few years, significant
new understandings of the debonding behaviour of both flexurally
and shear strengthened RC beams have been achieved based on recent
research on the behaviour of FRP-to-concrete interface. These new
understandings are reflected in the national design standard of
China, Standard for FRP in Civil Engineering, which is being drafted.
This paper summarises relevant specifications adopted for such debonding
failures in the new Chinese standard.
research on intermediate crack Debonding in FRP-strengthened RC
of 4th International Conference on Advanced Composite Materials
in Bridges and Structures, (ACMBS IV) Calgary, Alberta, Canada,
July, 2004. CDROM
ABSTRACT: An important failure mode for an
RC beam strengthened with an externally bonded FRP plate is debonding
of the FRP plate from the soffit of the beam due to major flexural
cracks. In this failure mode which is commonly referred to as intermediate
crack (IC) debonding, debonding initiates at a critical section
in the high moment region and then propagates to one of the plate
ends. Despite many experimental and theoretical studies, accurate
predictive models for IC debonding failures have not been developed.
This paper presents a new smeared crack approach for the finite
element simulation of the IC debonding process, in which a new model
for the FRP-to-concrete interface capable of capturing the effect
of local slip concentration near a flexural crack is proposed. The
finite element model is shown to be accurate through comparisons
with the results of 45 beam tests. The paper also presents an accurate
and simple design model based on interfacial shear stress distributions
from finite element analysis. The new design model is shown to be
accurate through comparisons with the test results of 73 beams,
including the 45 beams used in verifying the FE model.