International
RILEM Conference on Materials, Systems and Structures in Civil Engineering
Conference segment on Service Life of Cement-Based Materials and Structures
22-24 August 2016, Technical University of Denmark, Lyngby, Denmark
Only three participants have submitted some results about cracking in the gusset: Team 50,
Team 25 and Team 40. Each team uses a different methodology. Although, comparing results
is difficult. Only Team 50 and Team 40 have given some quantitative results about number of
cracks, spacing between cracks or openings.
All teams give results after 4 days of concrete pouring. At 4 days after the pouring, the
spacing between two cracks is about 0.8-2m (cf. team 40 and 50), while in situ observations
show a spacing of 1.2 m. Therefore, the width of the cracks at 4 days is about 0.07-0.1mm,
which is similar to what is observed in situ. Given to team 50, the maximum opening of the
cracks increases significantly from 0.1 at 4 days to 3.3 mm at 10 months.
2.2 Theme 2: prediction of the behavior of the containment wall
The predictions of the behavior of the containment wall were expected at different steps:
before prestressing, after prestressing and at 5.2 bar abs. during the pressurization test. The
strains and stresses in 10 points defined in the gusset, the cylindrical wall and the dome, and
cracking state evaluation (inner face cracks, outer face cracks and through cracks) were
expected.
The experimental data are below
[Figure 8]
(the results are limited to the cylindrical part in
this paper).
Figure 8: Cylindrical part strains from pouring to first pressurization test
87
International RILEM Conference on Materials, Systems and Structures in Civil Engineering
Conference segment on Service Life of Cement-Based Materials and Structures
22-24 August 2016, Technical University of Denmark, Lyngby, Denmark
The experimental results showed in this part [Table 3] correspond to the visual inspection
made after the first pressurization test.
During this inspection, only cracks which had an
opening superior to 0.1mm were measured and mapped. The difference of cracking state
between these results and those showed in Theme 1 part can be explained by the fact that
during early age inspection, all visible cracks (without any criterion on the opening) were
measured and by the fact that prestressing can have closed some of the early age cracks.
Table 3: Visual inspection results on cracking; Total length and max opening measured.
Dome: Outer face Dome: Inner face Gusset: Outer face Gusset: Inner face
Number
38 197 28 0
Total length (m)
13.73 138.07 24.63
/
Max length (m)
1.16 1.66 3.14
/
Average length (m)
0.36 0.70 0.88
/
Max opening (mm)
0.10 0.10 0.10
/
NB: The cracks identified in the dome inner face are located on precast slab forms and don’t
reflect the dome mechanical behavior.
Nine teams answered Theme 2. Their results are given and compared to experimental results
in this part. Teams 70, 50, 37 and 24 began their calculation since the raft concreting. Teams
49, 21, 15 and 14 took the end of containment erection date as starting date. Team 23 took the
raft concreting date as starting date, but didn’t provide values for strains and stresses at the
end of concreting date.
The experimental results represented in this part are strains corrected from temperature
effects. The teams are divided into two groups:
Group 1, which includes teams which began their calculation since the raft concreting
(Team 70, 50, 37, 24, 23)
Group 2, which includes teams which began their calculation since the end erection
(Team 49, 21, 15, 14)
These 2 groups are separated by a vertical red line on the following graphs.
2.2.1 Strain evolution results
The results are presented for the cylindrical wall strain evolution, in tangential directions. The
results are quite the same in vertical direction.
Teams’ results are scattered
[Figure 9]
.
In both directions, all teams, except Team 15 for tangential strains, show a more or less high
shortening for all captors as experimental results.
Team 15 results for tangential strains show elongation for captors H5 ET and H6 IT and a
very low shortening for H1 ET.
88
International RILEM Conference on Materials, Systems and Structures in Civil Engineering
Conference segment on Service Life of Cement-Based Materials and Structures
22-24 August 2016, Technical University of Denmark, Lyngby, Denmark
Except for Team 14, the right evolution is predicted between the end of the erection and the
end of prestressing, and between the end of prestressing and the pressure test. But the
amplitudes are not always well reproduced.
Figure 9: H5 Extrados Vertical strains evolution
2.2.2 Prestressing effects in the cylindrical wall
On the following graph
[Figure 10]
, experimental results are represented by a red horizontal
line. The experimental results represented in this part are strains corrected from temperature
effects. The strains represented in this part correspond to strains between the end of
construction and the end of prestressing. As the prestressing begins short after the end of
construction, it can be assumed that they correspond to the prestressing effects, but also
include some shrinkage and creep effects.
Near the inner surface (figure not presented here), the vertical (not presented here) and the
tangential measured strains are greater than near the outer surface. This is also obtained in the
simulation for Teams 24, 21 and 14. For Teams 50, 37, 23 and 15, the vertical strains are the
same near the outer surface as near the inner surface. In general, in both directions,
prestressing effects are underestimated by the teams, except Team 49 which overestimates
them. Team 15 results for tangential prestressing effects show elongation for captors H5 ET
and H6 IT and a very low shortening for H1 ET. However in many cases, Teams 70 and 14
are closer than the others.