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SUB-TASK 2.1: LABORATORY-SCALE
INVESTIGATIONS
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
Damage Force (Pd)
NOTES ON TESTING APPROACH
Restraining Force (Pr)
Two methods were considered
(Method 1)
t
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.
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
• 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
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
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
TEST SETUP
Top Beam
Bottom Beam
Concrete Blocks
Test Specimen
Hydraulic Actuator
Split-flow valve
Electric Pump
Needle ValvePressure Gage
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
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)
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.
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)
REPAIR DESCRIPTION
Applying the Strip Heat Monitoring the Surface Temperature
COLOR OF STEEL AT ELEVATED TEMPERATURES
1400F1200F 1600F
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
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
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
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.
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
• 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
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
SUB-TASK 2.1: LARGE-SCALE
INVESTIGATIONS
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
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.
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
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
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
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
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
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
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
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
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
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
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
QUESTIONS, COMMENTS, AND DISCUSSION?
