1
SWANSON school of engineering
civil and environmental engineering
structural engineering and mechanics
Watkins Haggart structural engineering laboratory
Extending the Life of Prestressed Concrete Bridge Infrastructure
Kent A. Harries, PhD, FACI, P.Eng University of Pittsburgh
Jarret Kasan, PhD HDR Inc., Pittsburgh
2
Two Stories…
Following the 2005 collapse of the Lake View Drive Bridge, Dr. Harries made a [bold] statement: This girder/bridge was repairable
The demonstration of this conclusion was developed through: • two PennDOT-funded projects • NCHRP Project 20-07/307 • two independent studies • one industry-funded investigation • and NCHRP Project 12-95
Resulting in: • seven refereed journal articles • three international conferences
presentations (Canada, Korea, UK) • four publically available technical
reports • one international research award
3
Motivation
Charlotte NC May 2000
Washington PA December 2005
Laval Qc October 2006
Unknown existing condition issues with precast concrete bridge girders…
… and impact damage…
4
Impact damage
Lake View Drive collapse onto I-70. Impact damage led to significant strand loss, subsequent corrosion and eventual collapse under girder self-weight.
Impact damage to facia beam of McIlvaine Road over I-70. Entire bridge was demolished within 24 hours.
Bridge over I-26 north of Columbia SC showing evidence of significant vehicle impact.
Crawford Lane over I-70 showing relatively minor impact damage
Subsequent damage from corrosion of exposed strand…
5
Damage Assessment: Cracking and Strand Loss
Typical damage from vehicle impact
Splitting-like cracks from a variety of sources
125% Rule
When considering strand loss, consider adjacent strands:
125% of observable strand loss when extent of corrosion is explored
150% when extent is not explored.
x x x x x
6
ltr
ld
fpe
fps
bondingcommences
sound concretesevered
strand
distance along strand
stra
nd s
tres
s
Damage Assessment: Strand ‘Redevelopment’
Typically, the contribution of severed and corroded strands will be neglected in load rating along the entire span.
However, the strand transfer length is ‘redeveloped’ through the Hoyer effect and strand-to-concrete bond.
Away from the damage, the strand remains fully developed and may be relied upon for capacity.
The Hoyer effect enhances prestress transfer through the diametric expansion of the strand
nominal
diameter
stressed diameter
Kasan, J. and Harries, K.A., 2011. Redevelopment of Prestressing Force in Severed Prestressing Strand, ASCE Journal of Bridge Engineering 16 (3)
7
Damage Assessment: Adjacent Box Girder Bridges
Loss of or absence of shear key and/or transverse tie rods result in individual girders acting independently
Increase in loads on girders:
Barrier wall loads not distributed to interior girders resulting in eccentric loading conditions on exterior girders
Live load increases approximately 66% based on AASHTO distribution factors.
Shear key details are presently the subject of newly awarded NCHRP Project 12-95 (PI: Dr. Brent Phares at Iowa State).
8
Damage Assessment: Adjacent Box Girder Bridges
Curb slab/barrier wall construction ultimately results in a composite asymmetric section having an eccentric load
Impact damage typically affects the exterior soffit corner resulting in additional asymmetry
Asymmetric damage to asymmetric sections loaded eccentrically results in significant biaxial flexural effects which reduce the actual and apparent capacity of the exterior girders.
Despite this, typical engineering assessment is 1D analysis K
asan
, J a
nd
Har
ries
, K.A
., 2
01
3. A
nal
ysis
of
Ecc
entr
ical
ly L
oad
ed A
dja
cen
t B
ox
Gir
der
s, A
SCE
Jo
urn
al o
f B
rid
ge
En
gin
eeri
ng
18
(1
)
9
Analysis of eccentrically loaded box girders
Biaxial nonlinear fiber element section analysis program (XTRACT)
Determines Mx-My failure surface based on user selected failure strains:
εcu = 0.003
εpu = 0.010
εsu = 0.100
Kasan, J and Harries, K.A., 2013. Analysis of Eccentrically Loaded Adjacent Box Girders, ASCE Journal of Bridge Engineering 18 (1)
10
Test Girder from Lake View Drive Bridge
Harries, K.A. (2009) Structural Testing of Prestressed Concrete Girders from the Lake View Drive Bridge, ASCE Journal of Bridge Engineering 14(2)
11
Test Girder from Lake View Drive Bridge
PLAN
A
84'-2" test span
rock anchorsELEVATION
Load Apparatus
Load Apparatus
48”
SECTION A-A
1 1/2” thread rodtension ties
double channelstrong back
double channelstrong back
4 - 60 kip hydraulichollow-core rams
rock anchors
support block
footing
steelstub
column
Har
ries
, K.A
. (2
00
9)
Stru
ctu
ral T
esti
ng
of
Pre
stre
ssed
Co
ncr
ete
Gir
der
s fr
om
th
e L
ake
Vie
w D
rive
Bri
dge
, ASC
E J
ou
rna
l of
Bri
dg
e E
ng
inee
rin
g 1
4(2
)
12
Test Girder from Lake View Drive Bridge
0
10
20
30
40
50
60
70
80
0 1 2 3 4
Applie
d L
oad, P
(kip
s)
Lateral Deflection at Midspan (in.)
top flange
bottom flange
0
10
20
30
40
50
60
70
80
0 2 4 6 8 10
Applie
d L
oad, P
(kip
s)
Deflection , (inches)
P P
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
0 2 4 6 8 10
Late
ral D
efle
ction (
in)
Midspan Deflection, (in)
P P
Harries, K.A. (2009) Structural Testing of Prestressed Concrete Girders from the Lake View Drive Bridge,
ASCE Journal of Bridge Engineering 14(2)
13
Analysis of Lake View Drive Exterior Girder
WEST EAST
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 25 m
A B C D E F G H J
impact damage at D damage at E impact damage at F damage at G spalling at J
Locate and identify nature and extent of damage along length of beam
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
14
Analysis of Lake View Drive Exterior Girder
Perform multiple 2D sections analyses, stitching these together considering ‘redevelopment’ of severed strands.
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 250
2000
4000
6000
5000
3000
1000
8000
7000
distance along beam, west to east (m)
mom
ent,
kNm
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
15
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 250
2000
4000
6000
5000
3000
1000
8000
7000
distance along beam, west to east (m)
mom
ent,
kNm
moment due to girder self weight
moment due to self weightplus 326.5 kN applied load
326.5 kN applied axle load
111.2 kN applied axle load
Analysis of Lake View Drive Exterior Girder
Applied moment
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
16
Analysis of Lake View Drive Exterior Girder
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 250
2000
4000
6000
5000
3000
1000
8000
7000
distance along beam, west to east (m)
mom
ent,
kNm
barrier wall
NORTH web
Observed Failure and Damage
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
17
Analysis of Lake View Drive Exterior Girder
0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 250
2000
4000
6000
5000
3000
1000
8000
7000
distance along beam, west to east (m)
mom
ent,
kNm
100% strand removed 125% strand removed1D analysis:
2 100% strand removed 125% strand removedD analysis:
Significant over estimation of capacity using conventional 1D analysis.
Underestimation of capacity if only critical section is considered.
In this case, 125% rule accounted for additional unseen damage.
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
18
Field testing of Prestressed Box Girder
Damaged exterior girder recovered from decommissioned bridge in SW PA
Harries, K.A., Holford, A. and Kasan, J. 2013. Demonstration of Fiber Optic Instrumentation System for Prestressed Concrete Bridge Elements, ASCE Journal of Performance of Constructed Facilities
Girder at test site prior to recasting top slab
Applied loading using same set-up as Lake View Drive study Impact and subsequent
deterioration damage documented
19
Field testing of Prestressed Box Girder
Girder capacity predictions made accounting for eccentricity and
strand redevelopment
Harries, K.A., Holford, A. and Kasan, J. 2013. Demonstration of Fiber Optic Instrumentation System for Prestressed Concrete Bridge Elements, ASCE Journal of Performance of Constructed Facilities
Instrumentation using innovative fiber optic system based on the principle of microbending and the measurement of intensity modulation.
20
Field testing of Prestressed Box Girder
High precision data that tracked girder behaviour even at low stress levels.
Outstanding correlation with predictions including measurements not otherwise possible to obtain in situ.
Har
ries
, K.A
., H
olf
ord
, A. a
nd
Kas
an, J
. 20
13
. Dem
on
stra
tio
n o
f F
iber
Op
tic
Inst
rum
enta
tio
n S
yste
m fo
r P
rest
ress
ed C
on
cret
e B
rid
ge E
lem
ents
, ASC
E
Jou
rna
l of
Per
form
an
ce o
f C
on
stru
cted
Fa
cili
ties
21
So…where are we?
Following the 2005 collapse of the Lake View Drive Bridge, Dr. Harries made a [bold] statement: This girder/bridge was repairable
Improved understanding and execution of in situ assessment.
Integration of beneficial effects of strand redevelopment.
Analytic tools that better capture anticipated eccentric behavior of exterior box girders.
Tools for improved SHM of in situ structures.
Now we need to establish which girders can be repaired and by which means.
22
Establishing a ‘Spectra of Repair’
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction 17 (6)
Extensive study involving the design of 541 repairs of 3 prototype girders subject to damage ranging from minor to severe.
Each repair was assessed based on practicality, constructability and LRFR rating and compared to its original ‘as built’ capacity.
23
Establishing a ‘Spectra of Repair’
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction 17 (6)
Prototype girders (3):
Adjacent and Spread Box Girders and AASHTO I-girders
Impact damage resulting in :
1.8% to over 40% strand loss; residual capacity as low as 40% of as built
Repair techniques (10):
strand splicing EB-CFRP strip EB-CFRP fabric bPT-CFRP uPT-CFRP P-CFRP NSM-CFRP PT-steel steel jacket hybrid replace girder
Normalized rating factors:
for which,
CD ≥ 1.1DC + 1.1DW + 0.75(LL+IM) ±γPP
Undamaged girder: RF0 =1.0
Damaged girder: RFD < 1.0
Repaired girder: RFR > RFD
Objective is to determine whether RFR is adequate for continued operation.
PDWDCC
PDWDCCRF
PDWDC
PDWDCD
D
0
24
Establishing a ‘Spectra of Repair’
Example: Exterior AB girder repaired with EB-CFRP
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
rep
aire
d r
atin
g f
acto
r, R
FR
damaged rating factor, RFD
AB 3-2-0 example (see text)
AB 2-1-0 with 2-50mm CFRP strips (see text)
AB
3-2
-0
as-b
uil
t R
F0
= 1
.0
most
damaged
least
damaged
AB
6-5
-2-2
-2
AB
2-1
-0
AB
1-0
-0
maximum feasible repair
(24-50 mm CFRP strips)
unrepaired RFR
18- 50mm CFRP strips
6-50mm CFRP strips
12-50mm CFRP strips
objective RFR = 1.0
range of
damage
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction 17 (6)
25
Establishing a ‘Spectra of Repair’
Example: Exterior AB girder repaired with EB-CFRP
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
rep
aire
d r
atin
g f
acto
r, R
FR
damaged rating factor, RFD
AB 3-2-0 example (see text)
AB 2-1-0 with 2-50mm CFRP strips (see text)
AB
3-2
-0
as-b
uil
t R
F0
= 1
.0
most
damaged
least
damaged
AB
6-5
-2-2
-2
AB
2-1
-0
AB
1-0
-0
maximum feasible repair
(24-50 mm CFRP strips)
unrepaired RFR
18- 50mm CFRP strips
6-50mm CFRP strips
12-50mm CFRP strips
objective RFR = 1.0
range of
damage
15 – 50 mm EB CFRP strips
Damaged girder: RFD = 0.88
Repaired girder:
RFR = 1.05
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction 17 (6)
26
Limitations of Repair Techniques
all external
techniques CD ≥ 1.1DC + 1.1DW + 0.75(LL+IM) ±γPP
Repair
Technique
Limitation of Repair Techniques
Geometric
Constraint CFRP Bond
Maximum number of strands
replaced
EB-CFRP
soffit:
bf ≤ b
bPT-CFRP can also restore lost
prestress force:
bPT-CFRP
soffit:
bf ≤ ≈0.5b
NSM-CFRP
soffit:
bf ≤≈0.5b εfd = 0.7εfu
strand
splices
limited to developing 0.85fpu in stands 12.7 mm diameter or less; therefore
effective number of strands restored by strand splices = 0.85nspliced
limited to splicing 15% of strands in a girder regardless of staggering
fu
ff
cfd 9.0
tnE
'f083.0
fufu
ff
cfd 9.0
tnE
'f083.0
HAf
HbntEn
ppu
fdfffmax
ppe
fufffPTmax
Af
bntEn
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction 17 (6)
27
Hybrid Repair – Strand Splices and EB-CFRP
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Repair of Prestressed Concrete Girders Combining Internal Strand Splicing and Externally-Bonded CFRP Techniques, ASCE Journal of Bridge Engineering
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
repair
ed r
ati
ng f
acto
r, R
FR
damaged rating factor, RFD
as-
bu
ilt
RF
0=
1.0
damaged
prototype girder
RFD = 0.59
objective RFR = 1.0
installation of 5
strand splices
RFR = 0.79 see Figure 4
additonal installation
of 4 plies EB-CFRP
RFR = 0.95
560 mm
178
mm
Example: Exterior IB girder (25% strand loss):
28
Hybrid Repair – Strand Splices and EB-CFRP
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Repair of Prestressed Concrete Girders Combining Internal Strand Splicing and Externally-Bonded CFRP Techniques, ASCE Journal of Bridge Engineering
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
repair
ed r
ati
ng f
acto
r, R
FR
damaged rating factor, RFD
as-
bu
ilt
RF
0=
1.0
damaged
prototype girder
RFD = 0.59
objective RFR = 1.0
installation of 5
strand splices
RFR = 0.79 see Figure 4
additonal installation
of 4 plies EB-CFRP
RFR = 0.95
560 mm
178
mm
Example: Exterior IB girder (25% strand loss):
undamaged strandrepaired with strand splice
not repaired
4 plies EB-CFRP
1 ply CFRP U-wrap
29
So…was Harries right or just a braggard?
Following the 2005 collapse of the Lake View Drive Bridge, Dr. Harries made a [bold] statement: This girder/bridge was repairable
First, some history:
The BIV-48 girder had 60 – 3/8” 250 ksi strands. From inspections:
1994: 14 of 60 (23%) strands reported severed RFD ≈ 0.77
2004: 20 of 60 (33%) strands reported severed RFD ≈ 0.66
post collapse: 32 of 60 (53%) strands reported severed RFD ≈ 0.47
30
So…was Harries right or just a braggard?
Following the 2005 collapse of the Lake View Drive Bridge, Dr. Harries made a [bold] statement: This girder/bridge was repairable
Residual capacity of girder was inadequate – the girder collapsed under its own self weight!
CD < 1.1DC + 1.1DW + 0.75(LL+IM)
Although this could have been remediated by:
• removing wearing surface; replacing with composite deck
• replacing 700 lb/ft barrier wall with steel barrier rail (girder was no behaving compositely with bridge therefore 100% of barrier load carried by exterior girder)
31
So…was Harries right or just a braggard?
Following the 2005 collapse of the Lake View Drive Bridge, Dr. Harries made a [bold] statement: This girder/bridge was repairable
RFD ≈ 0.47
Maximum available repairs:
EB-CFRP RFR ≈ 0.75
bPT-CFRP RFR ≈ 1.08
Strand splicing and NSM-CFRP is not recommended for box girders
So… technically, the girder was repairable and, being an exterior girder, was perhaps adequate with a rating factor of about 0.75.
32
Bibliography
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Repair of Prestressed Concrete Girders Combining
Internal Strand Splicing and Externally-Bonded CFRP Techniques, ASCE Journal of Bridge Engineering
Kasan, J.L., Harries, K.A., Miller, R.A. and Brinkman, R. 2013. Limits of Application of Externally-Bonded CFRP
Repairs for Prestressed Concrete Girders, ASCE Journal of Composites for Construction
Harries, K.A., Holford, A. and Kasan, J. 2013. Demonstration of Fiber Optic Instrumentation System for
Prestressed Concrete Bridge Elements, ASCE Journal of Performance of Constructed Facilities
Kasan, J and Harries, K.A., 2013. Analysis of Eccentrically Loaded Adjacent Box Girders, ASCE Journal of Bridge
Engineering
Briere, V., Harries, K.A., Kasan, J. and Hager, C. 2013. Dilation Behavior of Seven-Wire Prestressing Strand – The
Hoyer Effect, Journal of Construction and Building Materials
Harries, K.A. and Kasan, J.L. 2012. Assessment of Damaged Prestressed Adjacent Box Girder Bridges: A Case
Study, Proceedings of 14th International Conference on Structural Faults and Repair Edinburgh
Kasan, J. and Harries, K.A., 2011. Redevelopment of Prestressing Force in Severed Prestressing Strand, ASCE
Journal of Bridge Engineering
Kasan, J. and Harries, K.A. 2010. Repair of Prestressed Concrete Adjacent Box Girder Bridges, Proceedings of
the International Conference on Short and Medium Span Bridges, Niagara Falls, Canada
Kasan, J. and Harries, K.A. 2009. Repair of Impact-damaged Prestressed Concrete Bridge Girders with CFRP,
Proceedings of the Asia-Pacific Conference on FRP in Structures (APFIS 2009), Seoul.
Harries, K.A. 2009. Structural Testing of Prestressed Concrete Girders from the Lake View Drive Bridge ASCE
Journal of Bridge Engineering
33
SWANSON school of engineering
civil and environmental engineering
structural engineering and mechanics
Watkins Haggart structural engineering laboratory
Extending the Life of Prestressed Concrete Bridge Infrastructure
Kent A. Harries, PhD, FACI, P.Eng University of Pittsburgh
Jarret Kasan, PhD HDR Inc., Pittsburgh