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The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
TESTS FOR THE EVALUATION OFBOND PROPERTIES OF FRP
BARS IN CONCRETEMaurizio Guadagnini, Kypros Pilakoutas, Peter Waldron
Centre for Cement and ConcreteUniversity of Sheffield, Sheffield, S1 3JD, UK
Zenon AchillidesPublic Works Department, Cyprus
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Outline
•Introduction
•Testing Programme
•Pull-out tests and results
•Splitting tests and results
•Conclusions
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
•Bond between concrete and reinforcement is a fundamental aspect of the composite action of reinforced concrete
•Reliable test methods are needed for the characterization of the wide range of FRP reinforcing bars available in the global market
Introduction
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
i-RRT International Round Robin Test for the Evaluation of Bond of FRP Bars in Concrete
http
://w
ww
.shef
.ac.
uk/~
tmrn
et/r
rt
ConFibreCrete Network
fib TG 9.3
ISIS Canada
6 manufacturers10 FRP bars13 laboratories
CEB-FIPCEB-FIPfib
•To assist international committees to assess test methods for bond
•To provide a comparison of results between different laboratories
•To compare the bond properties of the different bar tested
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Testing Programme: sample specimens
Ribbed20646012SteelS-12
Ribbed41-55517-120710GlassRe-Bars Chile S.A.ReB-G
Peel Ply459008x8GlassEurocrete LtdEUR-G
Ribbed (smooth)417589.8GlassMarshall IndustriesCBAR-G
Ribbed (smooth)114172410.3CarbonMarshall IndustriesCBAR-C
Sand Coated426899.5GlassPultrall IncPUL-G
Sand Coated Helical Wrap40.862015.8GlassHughes BrothersHB-G5
Sand Coated Helical Wrap40.86909.53GlassHughes BrothersHB-G3
Sand Coated Helical Wrap40.87606.35GlassHughes BrothersHB-G2
Sand Coated130280010CarbonSireg SpaSIR-C
Peel ply60135010AramidSireg SpaSIR-A
Surface finishE(GPa)
fu(MPa)
φ(mm)
TypeManufacturerBar
Parameters investigated:- Type of composite- Diameter- Surface treatment
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Testing Programme: sample specimens
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Testing Programme: overview
Pull-out test: to simulate the bond strength of bars in confined conditions
Splitting test (eccentric pull-out): to simulate the bond strength of bars near the surface
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Pull-out Test: specimen set-up and data collection
Pull-out force Average bond stress Average slip End slip
Positioning of the bar in the concrete cube and test set-up
Data collection
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
15.15±1.311.23±0.2834.27±2.95S-12
10.53±0.952.29±1.4632.13±1.50ReB-G
9.24±0.660.70±0.1128.21±4.22EUR-G
21.30±0.871.19±0.0733.52±1.31CBAR-G
16.93±0.671.17±0.2416.53±01.12CBAR-C
9.24±0.660.84±1.0959.16±1.37PUL-G
14.04±1.823.29±0.9655.74±7.23HB-G5
16.44±0.710.87±0.1023.45±1.01HB-G3
16.03±2.451.13±0.1310.15±1.55HB-G2
13.70±0.480.30±0.0521.23±0.75SIR-C
10.01±1.540.64±0.0415.73±2.42SIR-A
τpull-out max(MPa)
δLpeak(mm)
Pu(kN)
Bar
Pull-out Test: results
Specimen PUL-G after pull-out Specimen ReB-G after pull-out
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Pull-out test of specimen SIR-C
Pull-out Test: results
Typical average bond stress vs. slip relationships
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Pull-out Test: results
Pull-out test of HB specimens
Variation in the post peak behaviour withina group of similar bars
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Energy approach:
Energy required to generate a given displacement of the
loaded-end (ω-α)
Energy dissipated during the progression of failure (δ)
Pull-out Test: results
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Splitting Test: specimen set-up and data collection
Pull-out Average bond Average slip End slip crack inducedforce stress displacement
Positioning of the bar in the concrete cube and test set-up
Data collection
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
PCF4.17±1.169.40±2.70S-12
TCF5.15±0.078.05±0.07ReB-G
TCCD3.30±0.664.20±0.82EUR-G
PCF4.30±1.916.47±2.81CBAR-G
PCF3.50±0.955.80±161CBAR-C
TCF5.10±0.957.23±1.40PUL-G
TCF4.40±0.5017.37±2.00HB-G5
TCF4.47±1.866.37±2.58HB-G3
TCF3.27±0.812.07±0.55HB-G2
TCCD5.50±0.878.63±1.42SIR-C
TCCD4.87±1.127.67±1.72SIR-A
Failure mode
τsplitting max(MPa)
Pu(kN)
Bar
Splitting Test: results
The crack pattern observed varied considerably within the whole set of tested specimens as well as within each group
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Instant crack
Sliding crack
Typical crack patterns
Multiple crack
Splitting Test: results
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Conclusions: Reliability of testing methodology
•Pull-out tests seem to yield consistent results (averageCV=8%; maxCV=15%)
•Splitting tests data were highly variable (averageCV=23%; maxCV=40%)
•The natural variability of concrete highly affects splitting behaviour
•Improved instrumentation set-up to reduce error
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Conclusions: Bond behaviour
•Pull through type of failure always occurs in well confined situations
•Bars with smaller diameter develop higher average maximum bond strength
•Sand coated bars seem to perform best
The Second International Conference on FRP Composites in Civil Engineering 8-10 December 2004 - Adelaide, Australia CICE 2004
Splitting to pull-out bond ratio
Conclusions: Bond behaviour (continued)
•Maximum average bond stress in unconfined conditions can be up to 80% lower than in confined conditions
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