Concrete Today May 2010 - the Irish Concrete Federation

concrete today - fibre reinforced polymer
Figure 5: Condition of GFRP inside a tested slab (No indication of rupture on bars)
Figure 6: Ruptured GFRP during material test
the failure load is very similar for both
slabs. This shows that CMA is the main
contributor to the ultimate capacity of the
slabs and since the capacity is far in excess
of the design load the lack of ductility is
not a significant issue. Serviceability on
the other hand, is ensured by the GFRP;
in the case of crack width when placed
near the surface only. Also there was no
evidence of complete GFRP rupture when
the embedded bars were examined after
tests (Figure 5 and Figure 6).
III. Compared with laterally restrained
slabs reinforced with an equivalent
amount of steel reinforcement those
reinforced with GFRP showed excellent
performance at ultimate load.
Therefore GFRP reinforcement can be a
substitute for steel in restrained slabs such
as bridge deck slabs.
Acknowledgement
• Irish Concrete Society for awarding
a Travel Bursary to attend the Fibre
Reinforced Polymer Reinforcement for
Concrete Structures 2009 Conference.
• Schock Bauteile GmbH, Germany
for generously providing GFRP
(ComBAR) material for the research
and staff at QUB for their supports
with experiments.
• Sengenia (http://www.sengenia.com/)
for providing Fibre Optic Sensors for
the research.
Reference
1. Read, J.A, ‘FBECR, The need for
correct specification and quality
control’, Concrete, Vol.23, 8, 23-27,
1989.
2. Clarke, J.L., The need for durable
reinforcement, Alternative Materials
for Reinforcement and Prestressing of
Concrete, Chapman & Hall, (1993).
3. Taylor, S.E. and Barry Mullin, ‘Arching
action in FRP reinforced concrete
slabs’, Construction and Building
Materials, 20, 71-80, (2006).
4. Tharmarajah, G., Robinson, D.J,
Taylor, S.E & Cleland, D.J, FRP
reinforcement for laterally restrained
slabs, Proceedings of Bridge and
Infrastructure Research in Ireland
2008, December 2008.
5. Tharmarajah, G., Cleland, D.J., Taylor,
S.E & Des Robinson, Compressive
Membrane Action in FRP reinforced
slabs, Proceedings of Fibre Reinforced
Polymer Reinforcement for Concrete
Structures 2009, July 2009.
6. Taylor, S.E., Rankin, G.I.B., Cleland,
D.J, ‘Arching action in highstrength
concrete slabs’, Proceedings
of the Institution of Civil Engineers
Structures and Buildings, Institution
of Civil Engineers,Vol.146,4, 353-362,
2001.
Table 2: Comparison of test results with some previous research results
Conclusion
The following conclusions were drawn
from this experimental study.
I. Restrained slabs can have substantial
ultimate capacity even with minimum
amounts of reinforcement.
II. GFRP reinforcement in laterally
restrained slabs showed excellent service
behaviour in terms of deflections and in
terms of crack widths.
Slab Reinforcement Reinforcement
yield stress (N/
mm 2 )
S5
(Taylor
et al.,
2006)
S6
(Taylor
et al.,
2006)
GFRP 0.5% at
Mid depth
Steel 0.5% at
Mid depth
fcu
(N/
mm 2 )
Failure
load
kN
504 67.9 200 12.0
530 85.0 210 15.0
Deflection
at 115 kN
load (mm)
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