1
Performance of Ultra-High Strength Concrete and FRP Retrofitted RC Slabs under Blast
Loads
School of Civil, Environmental and Mining Engineering,School of Civil, Environmental and Mining Engineering,The University of AdelaideThe University of Adelaide
Chengqing Wu, Oehler DJ, RebentrostM, Leach J, Whittaker AS
1. Introduction
• Terrorism
• Ultra-high Performance Concrete
• Retrofitting technologies
Why?
Mechanical properties of conventional concrete and UHPFC
1. Introduction
1300 mm
1000 mm
A A Section A-A
100 100 100150 150200 200
1.4
20
Test Specimen
Blast Test 1:
Blast Test 2:
Blast Testing of FRP retrofitted RC members
ELASTICRANGE
PLASTICRANGE
1. Introduction
2 Test Program
RetrofittingRetrofitting Ultra high performance concreteUltra high performance concrete
0
20
40
60
80
100
120
140
160
0 0.005 0.01 0.015
StrainStrain
Com
pres
sion
Str
ess
(Co
mpr
essi
on S
tres
s ( M
PaM
Pa))
Blast Testing SpecimensNormal Reinforced Concrete Specimens
MajorBending Plane
2000
1000
A A Section A-A
1000
Minor Bending Plane
100
10
2 Test Program
2
Pultruded:
240 240155 155210
Adhesive
10040
100 100 40
100CFRP 1.4 mm
Retrofitted Reinforced Concrete Specimens
Ultra-high Performance Concrete Specimens
Two slabs of UHPFC with and without reinforcement were designed.
2 Test Program
Testing Set-up
2 Test Program
Blast SetupBlast Setup
Concrete SlabConcrete Slab
Explosive ChargeExplosive Charge
Data acquisition
LVDTPressure Transducer (PT)
LVDT
20 mm
50 mm
PT1
PT2
Slab
Support
Support
2 Test Program
Experimental air blast program
201010.3711.4 %2000*1000*100RUHPFCD3ARUHPFC
34331.130.75-2000*1000*100UUHPFCD1BUUHPFC
50830.540.921.2 %2000*1000*100RC+CFRP 2.8mm strip, one side (EB)3BRET-2
10441.51.51.2 %2000*1000*100RC+CFRP 2.8mm strip, one side (EB)3ARET-1
82130.751.51.2 %2000*1000*100NSC RC1ANRC-4
34400.931.41.2 %2000*1000*100NSC RC1BNRC-3
81391.531.2 %2000*1000*100NSC RC1ANRC-2
10073.031.2 %2000*1000*100NSC RC1ANRC-1
Explosive Used(g)
Scaled distance(m/kg1/3)
Standoff distance
(m)
Reo. Rate
Dimensionmm*mm*mmDescriptionSlab
NameBlast
2 Test Program
3
Performance of Testing Specimens
NRC-3 crack development (a charge weight of 3.4kg at stand-off distance 1.4m, energy 2536 kN.mm)
NRC-4 crack development(a charge weight of 8kg at stand-off distance 1.5m, energy 5464 kN.mm)
Normal reinforced concrete slabs
Retrofitted Experimental Results
FlexuralDirect Shear
Direct Shear
FRP Debonding
(a charge weight of 5kg at stand-off distance 0.92m, energy 10375 kN.mm)
FRP DebondingUnreinforced ultra-high
performance fibre concrete slab
2 Test Program
(a charge weight of 3.4kg at stand-off distance 0.75m, energy 3089 kN.mm)
NRC-3 crack development (a charge weight of 3.4kg at stand-off distance 1.4m, energy 2536 kN.mm)
Normal reinforced concrete slabs
Reinforced ultra-high performance fibre concrete slab
(a charge weight of 20kg at stand-off distance 1m, energy 93077 kN.mm)
3 Blast Resistance
1010 2020 3030 4040 5050 6060
Deflection (mm)Deflection (mm)00
100100
200200
300300
400400
500500
600600
700700
Resi
stan
ce (
Resi
stan
ce (
kNkN)) Ultra high strengthUltra high strength
RetrofittedRetrofitted
Normal reinforced Normal reinforced concreteconcrete
4
Resistance, reflected impulses and energy demands and capacities
Comparison and Discussions
Based on this diagram, almost all specimens (except NRC-1) tested in this study will collapse.
4. Conclusion 4. Conclusion
A series of blast tests have been carried out to investigate blast resistance of the NRC, the retrofitted, the UUHPFC and the RUHPFC slabs. It was found that:
Although EB FRP compressive face of retrofitting can increase ductility in blast tests, the effectiveness of the retrofitting was inconclusive as slab failure was not achieved throughout the experiments.
The UUHPFC slab suffered even less flexural cracks at middle span by comparison with those for NRC slabs when it was subjected to similar blast loads, showing UHPFC is of high ductility and high energy absorption capacity, and is therefore a more effective material against blast loading.
Blast testing also validated the superior blast resistance of the RUHPFC slab due to the excellent mechanical properties of UHPFC.
P-I diagrams specified by current codes are very conservative whenthey are used to assess damage levels of specimens tested in this study.
4. Conclusion 4. Conclusion
Questions?