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3. For each bridge project, the research team designed two were shipped to the structures laboratory in Omaha,
42-ft-long specimens using the same number of strands Nebraska, within a month from their production date.
used in the actual bridge. At least one of the four ends of the Concrete cylinders made during production and coupons
specimens had to have the same end zone reinforcement of rebars were also sent to the structures laboratory with
details used on the actual bridge. the specimens.
4. The precast concrete girder companies reviewed the details
of the specimens and tried to find the right time to cast them
3.2.2 Description of the Test Specimens
next to some of the girders of the actual bridge project.
and Test Setup
Therefore, the specimens were fabricated using the same
material in the production of the girder of the actual bridge Table 3.1 summarizes the details of the eight specimens. The
and received the same level of treatment regarding curing details in this table include the specimen type, type of end zone
and strand release technique. reinforcement (EZR) details, material properties, number of
5. The precast concrete girder companies in Washington, prestress strands, and type of failure. Specimens are listed in
Virginia, and Florida allowed the research team to be the order in which they were fabricated and tested.
present at time of prestress release and to record any end The "proposed" detail was developed by the research team
zone cracking that might appear. Most of the specimens based on the research that was conducted at the University
Table 3.1. Design criteria of the full-scale specimens.
Girder #1 Girder #2
State Left End Right End Left End Right End
Girder Type EZR Type EZR Type EZR Type EZR Type
Repair Repair Repair Repair
TN1L TN1R TN2L TN2R
LRFD 2007 EZR Proposed EZR TN DOT EZR Proposed EZR*
No repair No repair No repair No repair
Tennessee
Construction Products, Inc., Jackson, Tennessee
Designed to fail in flexure
Type III '
AASHTO f ci = 6,000 psi, f c' = 7,000 psi
Beams Bottom: 30 straight 0.5 in., 270 ksi, low relaxation strands stressed to 33.8 kips
Top: 2 straight 0.5 in., 270 ksi, low relaxation strands stressed to 5 kips
7.5 in. thick CIP slab was added in the lab, f c' = 9,000 psi
WA1L WA1R WA2L WA2R
Proposed EZR* LRFD 2007 EZR NO EZR NO EZR
Washington No repair No repair No repair Epoxy Injection
State Concrete Technology Corporation (CTC), Tacoma, Washington
Designed to fail in shear
WF58G '
f ci = 6,000 psi, f c' = 8,000 psi
(Wide Flange
Super Girder) Bottom: 38 straight 0.6 in., 270 ksi, low relaxation strands jacked to 43.9 kips
Top: 20 straight 0.6 in., 270 ksi, low relaxation strands jacked to 43.9 kips
+ 4 "temporary" post-tension 0.6 in. diameter strands
VA1L VA1R VA2L VA2R
No EZR No EZR LRFD 2007 Proposed EZR*
No repair No repair EZR No repair
Virginia No repair
Bayshore Concrete Products, Cape Charles, Virginia
PCEF45 Designed to fail in flexure
(VA new '
f ci = 6,000 psi, f c' = 8,500 psi
Bulb-Tee)
Bottom: 38 straight 0.6 in., 270 ksi, low relaxation strands jacked to 43.9 kips
Top: 14 straight 0.6 in., 270 ksi, low relaxation strands jacked to 43.9 kips
4-in. thick, 47-in. wide deck slab was cast monolithically with the top flange
FL1L FL1R FL2L FL2R
FL DOT EZR Mod. FL DOT LRFD 2007 Proposed EZR*
No repair EZR EZR No repair
Florida
No repair No repair
Standard Concrete Products, Tampa, Florida
60-in. deep
Designed to fail in flexure
inverted T '
beams f ci = 6,000 psi, f c' = 8,500 psi
Bottom: 36 straight 0.6 in., 270 ksi, low relaxation strands jacked to 43.9 kips
10-in. thick, 24-in. wide CIP deck was added in the lab, f c' = 10,000 psi
* Proposed EZR is the end zone reinforcement recommended by Tuan et al. (16) and discussed in
Section 1.2.3 of this report.
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of Nebraska (16). As explained in Chapter 2, the LRFD Spec- 3.2.2.1 Tennessee Specimens
ifications (18) and University of Nebraska proposed detail (16),
Construction Products, Inc. of Jackson, Tennessee, fab-
recommend that the end zone reinforcement should be ricated two 42-ft-long Type III AASHTO I-girders for the
designed to resist 4% of the total prestressing force at trans- project. Each specimen had thirty 0.5-in. diameter, 270 ksi,
fer, and that the reinforcement should be designed for a ser- low relaxation prestressing strands, stressed to 33.8 kips per
vice stress not exceeding 20 ksi. However, the LRFD Specifi- strand. They also contained two partially stressed 0.5-in.
cations states that this reinforcement should be distributed diameter strands in the top flange, stressed to 5 kips per strand.
within h/4 (one-fourth of the depth of the girder) from the The specimens were designed to fail in flexure. Of the four ends,
end of the girder, while the University of Nebraska proposed two had the end zone reinforcement designed to the proposed
detail recommends that 50% of this reinforcement should be design; one was designed using LRFD specifications, and one
placed within h/8 (one-eighth of the depth of the girder) from contained the same end zone reinforcement existing on the
the end of the beam and the remainder should be placed be- typical Tennessee production girders. Figures 3.2 through 3.5
tween h/8 and h/2 from the end. show the details of the Tennessee specimens.
1'-4"
Strands pulled to 5 kips
7" 2#6 (A601) #6 (A601)
2 1/2"
4 1/2" 41'-10"
8" 2#5 (A500) each end, projecting 6"
(only appears on End TN2L)
1'-7" 7" 3'-9"
8" #5(A500)
6"
5'-6"
7 1/2" 8"
1'-4"
7" 6"
1'-10"
(a) Longitudinal Reinforcement
5"
#5(H500) or #6(H600)
H500 or H600
10"
4'-0"
90°
#3(HA310) HA301
#3
(HA300) 10"
7 1/8"
HA300 5 1/2"
11"
1'-8"
(b) Shear and Confinement Reinforcement
Figure 3.2. Cross section details of Tennessee specimens.
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Double Projected Bars H500 @ 6"
2 spa @ 4 1/2" = 9" 5"
2 spa @ 3" = 6" 3 spa @ 2" = 6"
3 pairs
of H600 4 pairs
@ 3" of H600
@ @2
3"
1"
12 HA300
12 HA300 +
+ 12 HA301
12 HA301 @ 6"
@ 6"
4.5" 1 1/2"
Figure 3.3. End zone reinforcement details of TN1L (LRFD) and
TN1R (proposed).
3.2.2.2 Washington State Specimens was more critical than having the strands draped. The force at
Concrete Technology Corporation (CTC) of Tacoma, the top of the girder from the prestressed strands and the post-
Washington, produced two 42-ft long, 58-in. deep Wash- tensioned strands created additional stresses in the girder web,
ington Super Girders (Wide Flange Girders). Each spec- amplifying the end zone cracks. The top and bottom strands
imen contained 38 straight 0.6-in. diameter, 270 ksi, low apply opposing flexural moments creating vertical tensile
relaxation prestressing strands in the bottom portion of the forces in the web.
girder, jacked to 43.9 kips per strand. At the top of the web, The specimens were designed to fail in shear. The first girder
each specimen contains 20 additional straight 0.6-in diam- had one end designed using the AASHTO LRFD specifications
eter prestressing strands and 4 "temporary" post-tension and the other using the proposed improved reinforcement
0.6-in diameter strands. The four "temporary" strands were design procedure. The other girder did not contain any addi-
included in an attempt to amplify the end zone cracking as tional end zone reinforcement other than the typical shear
much as possible. reinforcement. This was done to create the maximum amount
The production girders that the Washington specimens of end zone cracking possible for the girder. The precast pro-
were modeled after contained 20 draped prestressing strands. ducer stated that if they had a production girder that showed
However, none of the girder specimens manufactured for the the extent of end cracking experienced by the test specimens,
structural testing contained draped strands, so the top strands it would not be accepted. One of the ends that did not con-
in the Washington specimens remained straight. Having the tain additional end reinforcement received an epoxy injec-
prestressing strands remain straight at the top of the girder tion repair at the precast yard using the typical epoxy repair
Double Projected Bars H500 @ 6"
5"
Double Proj. 5 spa @ 3" = 1'-3" 3 spa @ 2" = 6"
Bar H600 (typ)
3" 4 pairs of
H600 @ 2"
6 pairs 1"
of H601
12 HA300
5 HA300 + 12 HA301
@ 6" @ 3"
4.5" 4 pairs of H501 1 1/2"
Figure 3.4. End zone reinforcement details of TN2L (TN) and TN2R (proposed).
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2" 1'-8" 2"
2" 2 1/2" (2) #4 bars
3 1/2" 2 1/2"
2" 2 1/2" (2) #3 bars
(2) #4 threaded
rods
Figure 3.5. Girder TN1 decking cross section.
procedure outlined in Manual for the Evaluation and Repair
of Precast, Prestressed Concrete Bridge Products (11). The
matching end was not repaired in any way. Figures 3.6
through 3.8 show the details of the Washington State
specimens.
3.2.2.3 Virginia Specimens
Bayshore Concrete Products of Cape Charles, Virginia,
donated two 42-ft long, 45-in. high bulb-T girders with thirty-
eight 0.6-in. diameter, 270 ksi, low relaxation prestressing
strands in the bottom flange and fourteen 0.6-in. diameter,
270 ksi, low relaxation prestressing strands in the top flange
of the girders, each tensioned to 44 kips. The straight pre-
stressing strands in the top of the girder were designed to
create additional vertical tensile stresses in the girder web,
amplifying end zone cracks. These girders were designed to
fail in flexure. Much like the Washington girders, two of the
girder ends did not contain any additional end zone rein- Figure 3.6. Details of Washington specimens.
forcement other than the typical shear reinforcement. The
remaining ends were designed using the AASHTO LRFD
Specification and the proposed improved details. In the end
that was designed using the proposed details, a #8 C-shaped They had thirty-six 0.6-in. diameter, 270 ksi, low relaxation pre-
bar was placed at 1 in. clear cover, in the same cross-sectional stressing strands in the bottom flange, tensioned to 43.94 kips
plane as one of the pairs of #5 bars in order to get a larger each, and six #6 bars of mild steel reinforcement along the
amount of steel closer to the girder end. None of the four ends top of the web. These six bars were placed to resist the top
were repaired in any way. Figures 3.9 through 3.11 show the tensile forces produced by the prestressing strands. On spec-
details of the Virginia specimens. imen FL1, one end contained the exact same configuration
for end reinforcement as the Florida production girders,
while the other end was designed to resemble the Florida
3.2.2.4 Florida Specimens
end reinforcement design. On specimen FL2, one end was
Standard Concrete Products of Tampa, Florida, produced designed using AASHTO LRFD specifications and the other
two 42-ft long, 60-in. deep inverted-T girders for the project. was designed using the proposed detail. After receiving the
