sub-task 2.1: laboratory-scale investigations. laboratory-scale description ninety one...
TRANSCRIPT
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SUB-TASK 2.1: LABORATORY-SCALE
INVESTIGATIONS
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LABORATORY-SCALE DESCRIPTION
• Ninety one laboratory-scale specimens were subjected to multiple damage-heat straightening repair cycles
• Focused on A36 and A588 steels due to the availability of material as apposed to older A7 and A373– A36 - closest in chemical compositions as A7 and A373
– A588 - third most relevant steel type from database
– Some A7 steel specimens were acquired from the web of a W24x76 steel beam
• Test specimen-test areas damage by uniaxial tensile forces and repaired with uniaxial compressive forces and by applying strip heats
• Material samples taken from the test areas to obtain statistically significant structural properties and fracture toughness
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Damage Force (Pd)
NOTES ON TESTING APPROACH
Restraining Force (Pr)
Two methods were considered
(Method 1)
t
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PROBLEMS WITH METHOD 1• The specimen cross-section and length are subjected to
different magnitudes of damage strain, restraining stress, and heat straightening repair.
• Hinders obtaining several material specimens subjected to consistent damage-repair magnitudes and testing them to obtain statistically significant structural properties.
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METHOD 2
Strip Heat
Damage Force (Pd )Repair Force (Pr )
• Specimen test-areas are subjected to consistent damage strains, restraining stresses, and heat straightening repair.
• Several material specimens are obtained from the test-areas and tested to obtain statistically significant structural properties.
• Method 2 was chosen in this research project.
Test Area
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• A36 – 28 Specimens• Three damage strains (d) – 30y, 60y , or 90y
• Two restraining stresses (y) – 0.25 y or 0.50y (0.40 y or 0.70 y for d = 30y)
• Number of damage-repair cycles (Nr) – 1, 2, 3, 4, or 5
• A588 – 30 Specimens• Three damage strains (d) – 20y, 40y , or 60y
• Two restraining stresses (y) – 0.25y or 0.50y
• Number of damage-repair cycles (Nr) – 1, 2, 3, 4, or 5
• A7 – 17 Specimens • Three damage strains (d) – 30y, 60y , or 90y
• Two restraining stresses (y) – 0.25y or 0.50y
• Number of damage-repair cycles (Nr) – 1, 3, or 5
• Three maximum heating temperatures
• Overheated A36 – 16 Specimens• Two damage strains (d) – 60y or 90y
• Two restraining stresses (y) – 0.25y or 0.50y
• Number of damage-repair cycles (Nr) – 1 or 3
• Two maximum heating temperatures - 1400F or 1600F
TEST MATRIX – 91 TOTAL SPECIMENS
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TEST SPECIMEN DETAILS
7.875
2.06 3.75 2.06
3.38
3.75
5.00
3.75
3.38
3.2539.00
13.25
Test specimen thickness = 0.45 in.
A7 steel
2.00
13.25
2.00
2.13 3.75 2.13
1.63
3.38
3.3816.88
3.75
3.75
16.88
1.63
3.38
3.38
3.25
8.00
46.25
Test specimen thickness = 1.00 in.
A36 and A588 steel
= 1.1875
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Cross-section at End B
1.0 in.
0.75
in.
0.394
4 5 6
0.75
in.
0.5 in.
0.394 0.394
3.25in.Cross-section at End B
1.0 in.
0.75
in.
0.394
4 5 6
0.75
in.
0.5 in.
0.394 0.394
3.25in.
1.0 in.1.0 in.
0.75
in.
0.394
44 55 66
0.75
in.
0.5 in.
0.394 0.394
3.25in.3.25in.
Cross-section at End B
Cross-section at End B
1.0 in.
0.75
in.
0.394
4 5 6
0.75
in.
0.5 in.
0.394 0.394
3.25in.Cross-section at End B
1.0 in.
0.75
in.
0.394
4 5 6
0.75
in.
0.5 in.
0.394 0.394
3.25in.
1.0 in.1.0 in.
0.75
in.
0.394
44 55 66
0.75
in.
0.5 in.
0.394 0.394
3.25in.3.25in.
Cross-section at End B
1.0 in.
0.5 in.
0.25 in.
0.75
in. 0.394 0.394 0.394
0.75
in.
21 3
3.25 in.
Cross-section at End A
1.0 in.
0.5 in.
0.25 in.
0.75
in. 0.394 0.394 0.394
0.75
in.
2211 33
3.25 in.
Cross-section at End ACross-section at End A
1.0 in.
0.5 in.
0.25 in.
0.75
in. 0.394 0.394 0.394
0.75
in.
21 3
3.25 in.
Cross-section at End A
1.0 in.
0.5 in.
0.25 in.
0.75
in. 0.394 0.394 0.394
0.75
in.
2211 33
3.25 in.
Cross-section at End ACross-section at End A
1 2 3
0.75 0.394 0.394 0.394 0.75
5.0 in.
4 5 6
0.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
11 22 33
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
5.0 in.
44 55 66
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
X Y1 2 3
0.75 0.394 0.394 0.394 0.75
5.0 in.
4 5 6
0.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
11 22 33
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
5.0 in.
44 55 66
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
X Y1 2 3
0.75 0.394 0.394 0.394 0.75
5.0 in.
4 5 6
0.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
11 22 33
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
5.0 in.
44 55 66
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
X Y1 2 3
0.75 0.394 0.394 0.394 0.75
5.0 in.
4 5 6
0.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
11 22 33
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
5.0 in.
44 55 66
0.75 0.394 0.394 0.394 0.750.75 0.394 0.394 0.394 0.75
3.25 in.
End B
End A
0.50.5
2.16
5 in
. 2.
165
in.
1.37
5 2.
25
1.37
5
X Y
MATERIAL COUPONS FROM TEST AREAS(A36 and A588 Specimens)
Charpy Specimens
Tension Coupons
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TEST SETUP
Top Beam
Bottom Beam
Concrete Blocks
Test Specimen
Hydraulic Actuator
Split-flow valve
Electric Pump
Needle ValvePressure Gage
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DAMAGE CYCLE-INSTUMENTATION
• Pressure transducers to measure actuator pressures• Two longitudinal strain gages in test area• Two displacement transducers to measure average
strain
Gage – front Gage -back
3.25 in.
5.0 in.
Test-Area
Two displacement transducers to measure average strains in test area
TEST AREA
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0
10
20
30
40
50
60
70
0 0.01 0.02 0.03 0.04 0.05 0.06 0.07 0.08 0.09Strain (mm/mm)
Str
ess
(ksi
)
Specimen A36-60-50-3 Target d = 0.080 in/in
Cycle 1-Longitudinal Strain Gages (Back (gray) and Front (red))
Cycle 1-Average Strain
Cycle 2 Average Strains
Cycle 3-Average Strains
Stress-strain of undamaged uniaxial tension test
EXPERIMENTAL DAMAGE BEHAVIOR(SPECIMEN A36-60-50-3)
Strain (in/in)
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REPAIR CYCLE-INSTRUMENTATION
Two displacement transducers to monitor movement during heat straightening
Infrared thermometer used to measure temperature on all sides
• Pressure transducers to measure actuator pressures• Infrared thermometer to measure surface temperature• Two displacement transducers to measure displacement
between top and bottom beam.
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0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
Time (s)
Pressure (psi) Temperature (F)
Right Displacement *10000 (in)
Left Displacement*10000 (in)
EXPERIMENTAL REPAIR BEHAVIOR(SPECIMEN A36-60-50-3)
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REPAIR DESCRIPTION
Applying the Strip Heat Monitoring the Surface Temperature
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COLOR OF STEEL AT ELEVATED TEMPERATURES
1400F1200F 1600F
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UNIAXIAL TENSION RESULTS (A36)
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 3 5 1 2 3 4 5
Rat
io o
f E
last
ic M
od
ulu
s to
Un
dam
aged
Mat
eria
l
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 3 5 1 2 3 4 5
Ra
tio
of
Yie
ld S
tre
ss
to
Un
da
ma
ge
d M
ate
ria
l
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 3 5 1 2 3 4 5
Rat
io o
f U
ltim
ate
Str
ess
to U
nd
amag
ed M
ater
ial
0.70
0.80
0.90
1.00
1.10
1.20
1.30
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 3 5 1 2 3 4 5
Ra
tio
of
%E
lon
ga
tio
n t
o U
nd
am
ag
ed
Ma
teri
al
d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y
d = 90y
r =0.50y
Number of damage-repairs (Nr)
d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y
Number of damage-repairs (Nr)
Number of damage-repairs (Nr)
d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y
ELASTIC MODULUS YIELD STRESS
ULTIMATE STRESS DUCTILITY % ELONGATION
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0.50
0.60
0.70
0.80
0.90
1.00
1.10
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 1 2 3 4 5
Rat
io o
f %
Elo
ng
atio
n t
o U
nd
amag
ed M
ater
ial
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5
Rat
io o
f %
Elo
ng
atio
n t
o U
nd
amag
ed M
ater
ial
DUCTILITY OF A36, A588, AND A7 STEEL d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y
Number of damage-repairs (Nr)
d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y
A588 STEEL
Number of damage-repairs (Nr)
0.50
0.60
0.70
0.80
0.90
1.00
1.10
1 3 5 1 3 5 1 3 3* 5 1 3 5 1 3 1 3
Rat
io o
f %
Elo
ng
ati
on
to
Un
dam
ag
ed
Ma
teri
al d = 30y
r =0.40y d = 30y
r =0.70y d = 60y
r =0.25y d = 60y
r =0.50y d = 90y
r =0.25y d = 90y
r =0.50y
A7 STEEL
Number of damage-repairs (Nr)
A36 STEEL
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CONCLUSIONS–STRUCTURAL PROPS.
• Multiple damage-heat straightening repair cycles have a slight influence (±15%) on the elastic modulus, yield stress, ultimate stress, and surface hardness of A36, A588, and A7 bridge steels
• The yield stress and surface harness increase slightly and the ultimate stress and elastic modulus are always within ±10% of the undamaged values
• However, the % elongation of damaged-repaired steel is influenced significantly
• The ductility (% elongation) of A36 and A588 steel decreases significantly but never lower than minimum values according to AASHTO requirements
• The ductility of A7 steel subjected to five damage-repair cycles is extremely low
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FRACTURE TOUGHNESS RESULTS (A36)
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
0 1 2 3 4 5 0 1 2 3 4 5
Fra
ctu
re T
ough
nes
s/ T
ough
nes
s U
nd
amag
ed A
36
d = 30y r = 0.40y d = 30y r = 0.70y
Number of damage-repairs (Nr)
95% low
95% high
Mean
95% high
Mean
95% low
0 = undamaged0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
0 1 2 3 4 5 0 1 2 3 4 5Fra
ctur
e T
ough
ness
/ Tou
ghne
ss U
ndam
aged
A36
95% high
Mean
95% low
95% high
Mean
95% low
d = 60y r = 0.25y d = 60y r = 0.50y
Number of damage-repairs (Nr)
0 = undamaged
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
0 1 3 5 0 1 2 3 4 5 4Fra
ctu
re T
ough
nes
s/ T
ough
nes
s U
nd
amag
ed A
36
95% high
Mean
95% low
95% high
Mean
95% low
d = 90y r = 0.25y d = 90y r = 0.50y
Number of damage-repairs (Nr)
0 = undamaged
• Fracture toughness of damaged-repaired specimens analyzed statistically mean toughness and 95% confidence interval (CI) high and low toughness values
• The 95% CI Low, mean, and 95% CI high toughness values of the damaged-repaired specimens were normalized with respect to the undamaged mean toughness of the corresponding steel.
• The normalized fracture toughness values for the damaged-repaired specimens are shown and the effects of parameters d, r, and Nr are evaluated.
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CONCLUSIONS - A36 FRACTURE TOUGHNESS
• The fracture toughness of A36 steel is much lower than the undamaged fracture toughness
• Mean fracture toughness of specimens damaged to 30y becomes less than 50% after two damage-repair cycles
• The fracture toughness of specimens damaged to 60y becomes less than 50% after three damage-repair cycles
• Mean fracture toughness of specimens damaged to 90y was found to have significant scatter
• Higher restraining stress appear to decrease the fracture toughness slightly
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• The fracture toughness of damaged-repaired A588 steel is greater than or close to the undamaged fracture toughness in several cases
• The fracture toughness never decreases below 50% (even after five damage-repair cycles)
• Increasing the restraining stress reduces the fracture toughness of A588 steel significantly
CONCLUSIONS - A588 FRACTURE TOUGHNESS
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CONCLUSIONS - A7 FRACTURE TOUGHNESS
• The fracture toughness of A7 steel decreases with an increase in r and Nr and with a decrease d
• The fracture toughness of steels damaged to 30y reduces to 50% of the undamaged toughness after three damage-repairs
• The fracture toughness of specimens damaged to 60y and repaired with 0.25y is excellent. However, increasing r has a significant adverse effect on the fracture toughness
• The fracture toughness of specimens damaged to 90y is close to the undamaged toughness after three damage-repair cycles
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SUB-TASK 2.1: LARGE-SCALE
INVESTIGATIONS
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LARGE-SCALE DESCRIPTION• Six beam specimens were subjected to three damage-heat
straightening repair cycles
• Two beam specimens were made of A7, two made of A36, and two made of A588
• Beams subjected to weak axis bending by applying concentrated forces at midspan– Similar to damage induced to the bottom flange of a composite beam
impacted by an over-height truck– Two flanges could be used for the removal of material samples as
apposed to one flange
– Easier to conduct, control, and repeat in a laboratory type setting as
compared to the composite beam damage
• Repair conducted by applying half-depth Vee heats along the damaged area of the beam
• Results of material testing used to validate the conclusions and recommendations of Sub-task 2.1
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LARGE-SCALE TEST MATRIX
Specimen ID d / y Mr / Mp-y p (in) Tmax (F)
Cycle # 1 2 3 1 2 3 1 2 3 1, 2, 3
A7-Beam 1 30 30 30 0.25 0.50 0.25 2.2 2.2 2.2 1200
A7-Beam 2 90 60 60 0.50 0.50 0.50 8.5 5.9 5.9 1200
A588-Beam 1 40 20 20 0.25 0.25 0.25 4.9 2.1 2.1 1200
A588-Beam 2 40 20 20 0.50 0.50 0.50 4.9 2.1 2.1 1200
A36-Beam 1 30 30 30 0.25 0.50 0.25 3.1 3.1 3.1 1200
A36-Beam 2 30 30 30 0.25 0.50 0.25 3.1 3.1 3.1 1400
d / y is the ratio of the damage strain in the extreme tension fiber to the yield strain
Mr / Mp-y is the ratio of the restraining moment in the heated steel to the weak-axis plastic moment capacity of the section
p is the plastic displacement at the point of loading after unloading Tmax represents the maximum heat temperature at the vee heat location
For each steel type, one damage-repair parameter was altered among the two specimens. The parameters were chosen from the results of
laboratory-scale testing.
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LARGE-SCALE TEST SETUP
Rotation Meter Rotation Meter
Midspan 12 in. Displacement Transducer
Quarter 6 in. Displacement Transducer
Quarter 6 in. Displacement Transducer
Infrared Thermometer
Longitudinal strain gage locations
p = 8.5 in d = 90 y
Support Column
Support Column
Beam Specimen (A7-Beam 2)
Threaded Rod
Loading Beam
Hydraulic Actuator
• Before damage - indicating instrumentation
• After damage – indicating key elements of test setup
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LOADING FRAME
a) Top Platesb) Semi-Circular Contact Shaftsc) 0.75 in. Threaded Rods
g) Hydraulic Actuatorh) 2.5 in. Threaded Rodi) Structural Plates and Nuts
d) Beam Specimene) Semi-Circular Contact Shaftsf) Loading Beam
ELEVATION VIEW SIDE VIEW
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DAMAGE CYCLES
• The damaging (upward) force was applied by the hydraulic actuator pushing the loading beam against the flanges
• Load was applied monotonically until the strain in the extreme tension fiber reached d from earlier table
• Instrumentation included:– Pressure transducers to measure actuator pressures– Six longitudinal strain gages at midspan to measure strains at the
top, bottom, and at bf / 3 from the top on both flanges
– Four displacement transducers to measure midspan and quarter deflections
– Four rotation meters used to measure the end rotations
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DISPLACEMENT DATA AT MIDSPAN WHILE DAMAGING (A36-Beam 1)
0
100
200
300
400
500
0 20 40 60 80 100Displacement (mm)
Loa
d (
kN)
Damage Cycle 1
Damage Cycle 2
Damage Cycle 3
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REPAIR CYCLES
• The restraining (downward) force was applied by the hydraulic actuator pulling down on the loading beam with additional attachments
• Two researchers applied Vee heats simultaneously to both flanges, spaced along the entire damaged region
• Heats were applied until the deflection of the beam was within 1/16 in. of the deflection before damage
• Instrumentation included:– Pressure transducers to measure actuator pressures
– Infrared thermometer used to measure the surface temperature of the Vee heat
– Four displacement transducers to measure midspan and quarter deflections
– Four rotation meters used to measure to measure end rotations
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L5 L4 L2 L1 C R1L3 R2 R3 R4 R5
4.50 in.
4.50 in.
9.46 in.
40.00 in.
VEE HEAT LOCATIONS AND NOMENCLATURE
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MATERIAL COUPSONS FROM BEAMS
C R1L1
X
Y
Z
8.00 in
2.50 in
4.50 in
0.75 in
0.75 in
0.75 in
9.00 in
L1 C R1
L1-1
L1-2
L1-3
L1-4
C-1
C-2
C-3
C-4 R1-4
R1-3
R1-2
R1-1
2.165 in
2.25 in
4.50 in 0.394 in
2.165 in 2.165 in
0.394 in
0.394 in
0.394 in
9.00 in
a) Tensile Coupons from Flange A
b) Charpy Specimens from Flange B
a) Tensile Specimens From Flange A
b) Charpy Specimens From Flange B
C R1L1
X
Y
Z
8.00 in
2.50 in
4.50 in
0.75 in
0.75 in
0.75 in
9.00 in
L1 C R1
L1-1
L1-2
L1-3
L1-4
C-1
C-2
C-3
C-4 R1-4
R1-3
R1-2
R1-1
2.165 in
2.25 in
4.50 in 0.394 in
2.165 in 2.165 in
0.394 in
0.394 in
0.394 in
9.00 in
a) Tensile Coupons from Flange A
b) Charpy Specimens from Flange B
a) Tensile Specimens From Flange A
b) Charpy Specimens From Flange B
• Three flat tensile coupons removed from the back flange (Flange A) of each beam specimen
• Twelve charpy specimens removed from the mid thickness of the front flange (Flange B) along the center of Vee heats L1, C, and R1
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NORMALIZED STRUCTURAL PROPERTIESResults are normalized to the statistical mean structural
properties of undamaged steel from the same plate
Specimen /Coupon y / yo E / Eo uuo e / eo Hd / Hdo
A7-Beam 1
X 1.16 1.01 1.01 0.96 -
Y 1.16 0.94 1.02 0.96 -
Z 1.25 0.93 1.06 0.81 -
Average 1.19 0.96 1.03 0.91 1.07
A7-Beam 2
X 1.07 0.95 1.03 0.80 -
Y 1.15 0.96 1.02 0.94 -
Z 1.20 0.94 1.03 0.80 -
Average 1.14 0.95 1.03 0.85 1.12
A588-Beam 1
X 0.94 1.00 0.90 1.03 -
Y 0.96 0.99 0.92 0.84 -
Z 1.07 1.01 0.98 0.79 -
Average 0.99 1.00 0.93 0.89 0.95
A588-Beam 2
X 0.89 0.97 0.89 1.02 -
Y 0.94 1.02 0.90 0.93 -
Z 1.08 0.98 0.99 0.81 -
Average 0.97 0.99 0.92 0.92 0.94
A36-Beam 1
X 1.07 1.00 0.98 0.97 -
Y 1.07 0.93 0.96 0.94 -
Z 1.07 1.04 0.98 0.88 -
Average 1.07 0.99 0.97 0.93 1.10
A36-Beam 2
X 1.21 1.04 1.05 0.89 -
Y 1.16 0.97 0.99 0.69 -
Z 1.10 0.98 0.98 0.79 -
Average 1.16 1.00 1.01 0.79 0.97
Specimen /Coupon y / yo E / Eo uuo e / eo Hd / Hdo
A7-Beam 1
X 1.16 1.01 1.01 0.96 -
Y 1.16 0.94 1.02 0.96 -
Z 1.25 0.93 1.06 0.81 -
Average 1.19 0.96 1.03 0.91 1.07
A7-Beam 2
X 1.07 0.95 1.03 0.80 -
Y 1.15 0.96 1.02 0.94 -
Z 1.20 0.94 1.03 0.80 -
Average 1.14 0.95 1.03 0.85 1.12
A588-Beam 1
X 0.94 1.00 0.90 1.03 -
Y 0.96 0.99 0.92 0.84 -
Z 1.07 1.01 0.98 0.79 -
Average 0.99 1.00 0.93 0.89 0.95
A588-Beam 2
X 0.89 0.97 0.89 1.02 -
Y 0.94 1.02 0.90 0.93 -
Z 1.08 0.98 0.99 0.81 -
Average 0.97 0.99 0.92 0.92 0.94
A36-Beam 1
X 1.07 1.00 0.98 0.97 -
Y 1.07 0.93 0.96 0.94 -
Z 1.07 1.04 0.98 0.88 -
Average 1.07 0.99 0.97 0.93 1.10
A36-Beam 2
X 1.21 1.04 1.05 0.89 -
Y 1.16 0.97 0.99 0.69 -
Z 1.10 0.98 0.98 0.79 -
Average 1.16 1.00 1.01 0.79 0.97
Specimen /Coupon y / yo E / Eo uuo e / eo Hd / Hdo
A7-Beam 1
X 1.16 1.01 1.01 0.96 -
Y 1.16 0.94 1.02 0.96 -
Z 1.25 0.93 1.06 0.81 -
Average 1.19 0.96 1.03 0.91 1.07
A7-Beam 2
X 1.07 0.95 1.03 0.80 -
Y 1.15 0.96 1.02 0.94 -
Z 1.20 0.94 1.03 0.80 -
Average 1.14 0.95 1.03 0.85 1.12
A588-Beam 1
X 0.94 1.00 0.90 1.03 -
Y 0.96 0.99 0.92 0.84 -
Z 1.07 1.01 0.98 0.79 -
Average 0.99 1.00 0.93 0.89 0.95
A588-Beam 2
X 0.89 0.97 0.89 1.02 -
Y 0.94 1.02 0.90 0.93 -
Z 1.08 0.98 0.99 0.81 -
Average 0.97 0.99 0.92 0.92 0.94
A36-Beam 1
X 1.07 1.00 0.98 0.97 -
Y 1.07 0.93 0.96 0.94 -
Z 1.07 1.04 0.98 0.88 -
Average 1.07 0.99 0.97 0.93 1.10
A36-Beam 2
X 1.21 1.04 1.05 0.89 -
Y 1.16 0.97 0.99 0.69 -
Z 1.10 0.98 0.98 0.79 -
Average 1.16 1.00 1.01 0.79 0.97
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CONCLUSIONS – STRUCTURAL PROPERTIES
• Damage-heat straightening repair cycles do not have a significant influence on the yield stress, elastic modulus, ultimate stress, or surface hardness of steel (15%)
• Damage-repair cycles reduce the percent elongation (ductility) of A7 and A36 steel
• For A588, damage-repair cycles slightly increase the percent elongation of the outmost (X) specimen and decrease the percent elongation of the middle (Y) and innermost (Z) specimens
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NORMALIZED FRACTURE TOUGHNESS
Location L1 C R1 Avg. L1 C R1 Avg.
A7-Beam 1 A7-Beam 2 1 0.73 0.13 0.25 0.37 2.03 1.07 2.85 1.98 2 0.23 0.07 0.14 0.15 2.42 0.84 0.89 1.38 3 0.19 0.14 0.13 0.15 1.04 0.12 0.88 0.68 4 0.12 0.09 0.12 0.11 0.13 0.22 0.18 0.18
Avg. 0.32 0.11 0.16 0.20 1.40 0.56 1.20 1.05
A588-Beam 1 A588-Beam 2 1 3.08 3.08 3.08 3.08 3.08 3.06 3.01 3.05 2 3.07 3.05 3.07 3.07 3.06 2.87 2.72 2.88 3 2.77 2.63 3.05 2.82 1.36 1.25 1.11 1.24 4 1.47 1.26 1.36 1.37 1.09 0.77 1.07 0.98
Avg. 2.60 2.51 2.64 2.58 2.15 1.99 1.97 2.04
A36-Beam 1 A36-Beam 2 1 1.53 0.36 2.18 1.36 2.07 4.61 4.05 3.57 2 1.48 1.53 0.83 1.28 2.52 3.19 4.23 3.31 3 0.38 0.36 1.44 0.73 2.07 1.24 2.43 1.91 4 0.24 0.25 0.36 0.28 1.01 0.40 1.64 1.02
Avg. 0.91 0.62 1.20 0.91 1.92 2.36 3.08 2.45
Results are normalized to the statistical mean fracture toughness of undamaged steel from the same flange plate
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CONCLUSIONS – FRACTURE TOUGHNESS• The fracture toughness of A7-Beam 1 subjected to Nr=3 and d=30y
is much lower than the undamaged toughness. The mean fracture toughness of A7-Beam 2 compares favorably with the undamaged toughness. However, some variability is seen in the results and the toughness of material closer to the flange-web junction (k-region) is much lower
• Damage-repair cycles increase the fracture toughness of A588 steel significantly to the ranges of 272-308% for the outermost two rows of charpy specimens. The fracture toughness values were smaller for charpy specimens closer to the flange-web junction
• The overall fracture toughness of A36-Beam 1 is comparable to the undamaged toughness. However, significant variability exists
• The fracture toughness of A36-Beam 2 increased significantly. The increase ranges from 101-460% of the undamaged toughness. There was one low value (40%)
• None of the significant conclusions and recommendations from the laboratory-scale testing (Sub-task 2.1) were altered by the results from the large-scale testing
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QUESTIONS, COMMENTS, AND DISCUSSION?