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Concrete Research at the University of Wollongong, Australia
Assoc Prof. Muhammad Hadi
1
Tim McCarthy Muhammad Hadi Alex Reminnokov Neaz Sheikh Tao Yu Shishum Zhang Lip Teh (Steel)
2
Faez Alhussainy, Hayder Alaa Hasan, Sime Rogic, M. Neaz Sheikh, Muhammad N.S. Hadi
3
4Details of direct tensile test for Concrete
5
6
Muhammad N. S. Hadi Faez Alhussainy M. Neaz Sheikh
7
Steel bars are traditionally used inreinforced concrete members.
In general steel bars are solid in crosssection.
Steel tubes that have the same crosssectional area as solid bars will havehigher second moment of area andstiffness.
Using steel tubes in lieu of solid bars willincrease the stiffness of concretemembers.
8Steel tubes
Steel bars
Self-Compacting Concrete is an innovative concrete that can
flow and consolidate under its only weight.
Placement of SCC by pump tremie
(Goodier, 2003)9(Mott MacDonald Ltd)
Self-Compacting Concrete Mix proportion
• Type of mix EFNARC (2002) method.
Self-compacting concrete mix proportion
Material Quantity/1m3 of concrete
Cement 280 kgMineral admixtures 170 kg
Fine aggregate 950 kgCoarse aggregate 780 kg
Water 182 kgHigh Range Water Reducer 3.375 l/ m3
Water/Powder ratio 0.4
10
Check fresh concrete properties with ASTM Methodsa) Slump flow test
Slump flow test
Calculate the slump flow (SF) according to the flowing equation:
Where :dmax = The maximum diameter of the circular spread of the SCC.
.
dperp = The perpendicular diameter to dmax.
This test was carried out according to ASTM C1611 (2014).
2max perpddSF
11
b) J- Ring test
J-Ring test
Calculate J-Ring flow (RF) according to the following equation:
Where:jmax= The maximum diameter of the circular spread of the SCC.jperp= The perpendicular diameter to jmax .
2max perpjjRF
12
This test was carried out according to ASTM C1621 (2014).
Passing Ability= slump flow – J-Ring flow
(250 mm)
(510 mm)
(170 mm)
(50 mm)
(115 mm)
(220 mm)
(230 mm)
(515 mm)
Detail of column mould Detail of collector plate
c) Column segregation test
• ASTM C-1610 (2014).
• This test evaluates the static stability of a concrete mixture.
• This test consists of filling a 660 mm high cylindrical mould with concrete.
(Based on ASTM C-1610, 2014)13
c) Column segregation test (cont'd)
WhereS % = percent static segregation.CAT = mass of coarse aggregate in the top section of the column.CAB= mass of coarse aggregate in the bottom section of the column.
Column test
Percent static segregation is calculated from equation:
100CACACACA2%S
TB
TB
,0%S
if CAB > CAT
if CAB ≤ CAT
14
b) Tensile testing of steel tube
• ASTM A370, (2014). • A design that used for such plugs is shown in Figure.
Gauge Length
d
d
d
d
d
Testing machine jaws should not extend beyond this limit
dd
2d
Metal plugs for testing tubular specimens
Metal plugs
(Based on ASTM A370, 2014)15
C) Compression testing of steel bars and tubes
(a) Steel bars (b) Steel tubes
Compressive test of samples16
Axial tension load-deformation curves for Specimens N12 and ST26.9
17
N12
ST26.9
Axial tension load-deformation curves for Specimens N16 and ST33.7
18
ST33.7
N16
19
Group 1 Group 2 Group 3 Group 4 Group 5
Experimental Program
20
GroupNo.
SpecimenLabels
Diameter (mm)
Height(mm)
Longitudinal Reinforcement Transverse Reinforcement Loading ModesNo.
of Bars or Tubes
External Diameterof Bars or
Tubes (mm)
Thickness of Tubes,
(mm) %
Diameter of Bars (mm)
Pitch (mm)
%
1
N16H50C 240 800 6 16 (N16) ‐‐‐‐‐ 2.67 R10 50 3.3 Concentric
N16H50E25 240 800 6 16 (N16) ‐‐‐‐‐ 2.67 R10 50 3.3 e = 25 mmN16H50E50 240 800 6 16 (N16) ‐‐‐‐‐ 2.67 R10 50 3.3 e = 50 mmN16H50F 240 800 6 16 (N16) ‐‐‐‐‐ 2.67 R10 50 3.3 Flexural
2
ST33.7H50C 240 800 6 33.7 2 2.64 R10 50 3.3 Concentric
ST33.7H50E25 240 800 6 33.7 2 2.64 R10 50 3.3 e = 25 mm
ST33.7H50E50 240 800 6 33.7 2 2.64 R10 50 3.3 e = 50 mm
ST33.7H50F 240 800 6 33.7 2 2.64 R10 50 3.3 Flexural
3
ST33.7H75C 240 800 6 33.7 2 2.64 R10 75 2.2 Concentric
ST33.7H75E25 240 800 6 33.7 2 2.64 R10 75 2.2 e = 25 mm
ST33.7H75E50 240 800 6 33.7 2 2.64 R10 75 2.2 e = 50 mm
ST33.7H75F 240 800 6 33.7 2 2.64 R10 75 2.2 Flexural
4
ST26.9H50C 240 800 6 26.9 2.6 2.63 R10 50 3.3 Concentric
ST26.9H50E25 240 800 6 26.9 2.6 2.63 R10 50 3.3 e = 25 mm
ST26.9H50E50 240 800 6 26.9 2.6 2.63 R10 50 3.3 e = 50 mm
ST26.9H50F 240 800 6 26.9 2.6 2.63 R10 50 3.3 Flexural
5
ST26.9H75C 240 800 6 26.9 2.6 2.63 R10 75 2.2 Concentric
ST26.9H75E25 240 800 6 26.9 2.6 2.63 R10 75 2.2 e = 25 mm
ST26.9H75E50 240 800 6 26.9 2.6 2.63 R10 75 2.2 e = 50 mm
ST26.9H75F 240 800 6 26.9 2.6 2.63 R10 75 2.2 Flexural
Details of Tested Specimens
21
Construction of formwork
Fabricated reinforcing cages
22
Strain Gauges
3D View 3D View 3D ViewSide Elevation View Side Elevation View Side Elevation View
Front Elevation ViewFront Elevation ViewFront Elevation View
Plan View Plan View Plan View
Positions of PFL‐10 Gauges for longitudinal reinforcement
Positions of FCA‐10 Biaxial Gauges for longitudinal
reinforcement
Positions of FLA‐5 Gauges for transvers reinforcement
Photo of Strain Gauge Gluing
23
After casting of specimensBefore casting of specimens
24 Typical set up of a column Specimen
Loading heads
Four point loading method
25
Columns groups N16H50 ST33.7H50 ST26.9H50 ST33.7H75 ST26.9H75
Maximum load (kN) 2734 2729 2598 2633 2443
26
Failure Modes
Tao Yutaoy@uow.edu.au
FRP = Fiber-Reinforced Polymer
0
10
20
30
40
50
60
70
0 0.01 0.02 0.03
axial strain
axia
l stre
ss (M
Pa)
unconfined concrete
Steel confined concrete
FRP confined concrete
1. Corrosion-resistant skin 2. Stay-in-place formwork for
casting concrete3. Confining device for
improved strength and ductility
FRP tube
Hybrid FRP-concrete-steel double-skin tubular structural columns (DSTCs)
Excellent ductility & seismic resistance Excellent durability Ease for construction
FRP tube
Concrete
Steel tube
No. Specimen ID.Thickness of FRP wrap
(ply)
Steel tube diameter (d/mm)
Steel tube thickness (t/mm)
Void ratio D/t
1 DSTC-A2-I, II 2 plies 139.7 3.5 (A) 0.68 39.9
2 DSTC-A3-I, II, III 3 plies 139.7 3.5 (A) 0.68 39.9
3 DSTC-A4-I, II 4 plies 139.7 3.5 (A) 0.68 39.9
4 DSTC-B3-I, II, III 3 plies 139.7 5.4 (B) 0.69 25.9
5 CFDSTC-A3-I, II 3 plies 139.7 3.5 (A) N/A 39.9
6 CFDSTC-B3-I, II 3 plies 139.7 5.4 (B) N/A 25.9
7 FCSC-2-I, II 2 plies - - - -
8 FCSC-3-I, II 3 plies - - - -
9 FCSC-4-I, II 4 plies - - - -
10 CESC-A-I N/A 139.7 3.5 0.68 39.9
11 CESC-B-I N/A 139.7 5.4 0.69 25.9
12 FCESC-H2-I, II 2 plies Dimensions of the H-section steel column
13 FCESC-H3-I, II 3 plies b h tf tw14 FCESC-H4-I, II 4 plies 100 152.6 6.8 6.131
Columns with a PET FRP Tube
0 10 20 30 40 50 60 70 80 900
500
1000
1500
2000
2500
3000
3500
Axi
al L
oad
(kN
)
Total Axial shortening (mm)
DSTC-A2-I DSTC-A3-I DSTC-A4-I Concrete Filled DSTC-A3-I
0 10 20 30 40 50 60 70 800
600
1200
1800
2400
3000
3600
4200
Axi
al L
oad
(kN
)
Axial Shortening (mm)
CFDSTC-B3-II FCSC-3-II DSTC-B3-II CESC-B
Near-surface mounted (NSM) fiber-reinforced polymer (FRP) reinforcement: An emerging and promising technique for
structural strengthening
Shishum Zhang
Flexural Strengthening of concrete members
Tension rebar
Stirrup
Adhesive FRP
Tension rebar
Stirrup
2c
1c
ea eagagagagw gw gw gw
ghghghgh
Groove Groove filler
fhbhbbbd
bb bwft
Externally bonded FRP laminates
Near-surface mounted FRP bars/strips
Cross-section of strengthened RC beams
The most important advantage of the NSM FRP method over the EB FRP method is the improved bond effectiveness between FRP and concrete, leading to a higher debonding strain of the FRP.
Bond between NSM FRP and concrete
Adjustablesupports
Rollers
Base plate
Bearing plate
Grip
Support block
Concrete block
lbPositioning frame
l
FRP strip/barEstablishment of the first ever 3-D meso-scale finite element model for bonded joints between a near-surface mounted (NSM) FRP strip and concrete.
Teng, J.G., Zhang, S.S., Dai, J.G. and Chen, J.F. (2013). “Three-dimensional meso-scale finite element modeling of bonded joints between a near-surface mounted FRP strip and concrete.”Computers & Structures, Vol. 117, pp. 105–117. (A* journal according to ERA ranking)
Bond-slip model between FRP and concrete
0
2
4
6
8
10
12
14
0 0.2 0.4 0.6 0.8 1 1.2 1.4
Loca
l bon
d st
ress
(MP
a)
S l ip (mm)
Proposed model (h_g/w_g=2.33)
Proposed model (h_g/w_g=4)
Proposed model (h_g/w_g=5.67)
FE analysis (h_g/w_g=2.33)
FE analysis (h_g/w_g=4)
FE analysis (h_g/w_g=5.67)
Can be :1) used to establish the bond strength model of NSM CFRP strip-to-
concrete bonded joints; and2) incorporated into FE models of RC structures strengthened with CFRP
strips to simulate the debonding failure process.
Formulation of the first accurate bond-slip model for CFRP strips near-surface mounted to concrete.
)22
sin()2( 2B
sBB
sBA
619.0422.04.0 cf fG 613.0138.0
max 15.1 cf
0.138 0.6130.72 cA f
0.284 0.0060.37 cB f
Zhang, S.S., Teng, J.G., Yu, T. (2013). “Bond-slip model for CFRP strips near-surface mounted to concrete.” Engineering Structures, Vol. 56, pp. 945–953. (A* journal according to ERA ranking)
Bond strength model between FRP and concrete
2u f f f failureP G E A C
2u L f f f failureP G E A C
66.1
eL
fff
failure
AEGC
2
2max2
0.0
50.0
100.0
150.0
200.0
250.0
300.0
0.0 50.0 100.0 150.0 200.0 250.0 300.0
Test
bon
d st
reng
th (k
N)
P rediction of the proposed model
5.67
Average=0.924STD=0.109CoV=0.118
Work done before joining UOW:Development of a bond strength model for NSM CFRP strip-to-concrete bonded joints, which is the first model that can accurately account for the effect of bond length on bond strength
FRP element cohesive element
P
Zhang, S.S., Teng, J.G., and Yu, T. (2014). “Bond strength model for CFRP strips near-surface mounted to concrete.” Journal of Composites for Construction, ASCE, in press. (A journal according to ERA ranking)
FE modelling of NSM FRP-Strengthened RC beamsTest FE prediction
Work done before joining UOW:Development of an accurate finite element model for predicting end cover separation failures in RC beams strengthened with FRP in flexureZhang, S.S. and Teng, J.G. (2014). “Finite element analysis of end cover separation in RC beams strengthened in flexure with FRP”, Engineering Structures, Vol. 75, pp.550-560. (A* journal according to ERA ranking)
Simplified FE model for debonding failure
Development of an accurate simplified finite element model
Zhang, S.S. and Teng, J.G. (2015). “End cover separation in RC beams strengthened in flexure with bonded FRP reinforcement: simplified finite element approach”, Materials and Structures, 49 (6), 2223-2236
Strength model for debonding failure in strengthened concrete beams
cearDbAEscR fbcl/separation 6.3
16.025.015.16.0008.0952.0
PP
PPR if
if
)08.0100
)(05.15.4( 023.1266.0 c
ccsc
ss
cs
19.04860 ff
AE EA
094.0
85.0
t
clear
Db D
bt
0
1000
2000
3000
4000
5000
6000
7000
0 1000 2000 3000 4000 5000 6000 7000
ε db
from
Sim
plifie
d FE
mod
el (μ
ε)
εdb from proposed model (με)
Average: 1.00STD: 0.070CoV: 0.070
Establishment of an accurate strength model for end cover separation failures in RC beams strengthened with FRP in flexure
Teng J.G., Zhang S.S. and Chen J.F. (2015). “Strength Model for End Cover Separation Failure in RC Beams Strengthened with Near-surface Mounted (NSM) FRP Strips”, submitted to Engineering Structures, under review. (A*journal according to ERA ranking)
Analytical solution to interaction forces between NSM FRP and beam
Analytical and numerical investigations on the prediction of interaction forces in beams strengthened with near-surface mounted FRP bars.
Zhang, S.S. and Yu T. (2015). “Analytical solution for interaction forces in beams strengthened with near-surface mounted round bars”, submitted to Construction and Building materials, under review. (A journal according to ERA ranking)
0)(
)(11)(2
2
2
xVIEIE
dk
xFAEAEIEIE
dk
dxxFd
Tffbb
fbl
lffbbffbb
fbl
l
01
)()(11)(44
qIE
k
dxxdF
IEy
IEykxF
IEIEk
dxxFd
bbv
l
ff
f
bb
bvv
ffbbv
v
0
10
20
30
40
50
60
0 10 20 30 40 50
Tang
entia
l inte
ract
ion
forc
e (N
/ mm
)
Distance from the NSM bar end (mm)
FE modelPresent method
-2
0
2
4
6
8
10
12
0 10 20 30 40 50Nor
mal in
terac
tion f
orce
(N / m
m)
Distance from the NSM bar end (mm)
FE modelPresent method
Novel FRP anchorage system
Novel FRP anchorage system
Adjacent concrete wall
Optical fibers with FBG sensors (to Optical Sensing Interrogator )
GFRP sheets
GFRP anchor
Novel FRP anchorage system
0
1500
3000
4500
6000
7500
9000
0 10 20 30M
icro
stra
in
Load (kN)
FBGStrain guage
Tensile tests
Bond tests
Novel FRP anchorage system
0
500
1000
1500
2000
2500
3000
0 5 10 15 20
Mic
rost
rain
Root moment (kN*m)
FBG-L-3FBG-L-4Strain guage
0
500
1000
1500
2000
2500
3000
3500
4000
4500
0 5 10 15 20 25
Mic
rost
rain
Root Moment (kN*m)
FBG-L-1FBG-L-2FBG-R-1FBG-R-2
0
500
1000
1500
2000
2500
3000
0 5 10 15 20
Mic
rost
rain
Root moment (kN*m)
FBG-R-3FBG-R-4Strain guage
0
5
10
15
20
25
30
0 10 20 30 40 50 60
Roo
t mom
ent (
kN*m
)
Free end deflection(mm)
SS-1SS-2
Unstrengthened SS-2: 17.5 kN*m
Unstrengthened SS-1: 15.3 kN*mSlab tests
Other projects
Smart FRP bars
Fiber-optic monitoring of FRP-strengthened RC slabs
Fiber-optic monitoring of underground jacking pipes
Alkaline Resistance of GFRP Bars
49
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