82
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
and shrinkage.
In 2021, to predict the behavior under severe accident conditions.
This paper is dedicated to the results of the first workshop where 14 teams (over 46 registred
for the benchmark [Figure 3]) have presented their blind results (only a part of the results is
presented).
Figure 3: Repartition of the registered participants
2. Benchmark VERCORS 2015
2.1 Theme 1: early age
The topic is the prediction of the gusset behavior at early age, from the pouring to ten month
(end of construction of the whole containment). The results expected were temperature
evolution, strains, stresses and cracking patterns.
2.1.1 Temperature evolution
For the first phase, 11 participants have proposed a temperature evolution in the gusset
[Figure 4]. A short summary of the results is presented in this paper.
We can note that the temperature values were underestimated during the first 50 hours and
that the experimental temperature plateau (between 10 and 35 h) was not found
[Figure 5]
.
This can be due to a poor evaluation of the heated air temperature around the gusset. The
obtaining of the plateau is directly linked to the duration of the air heating around the gusset.
The thermometer providing us with the heated air temperature around the gusset has
malfunctioned. Due to this unreliable measurement, new boundary conditions have been
proposed by EDF to the participants. Participants were free to use any numerical calibration:
the adjustment should only regard the boundary conditions of the gusset during heating. The
results were better.
83
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
Figure 4: Position in the gusset of the sensors concerned by the theme 1
Figure 5: Preliminary results - Temperature given by participants in the gusset (G1 and F1)
2.1.2
Evolution of tangential strains in the gusset
Four teams (Team 25, Team 40, Team 44 and Team 50) have submitted tangential strain
values in the gusset.
It shows that almost Teams overestimate the experimental strains for all sensors. The team 50
gives the best results
[Figure 6]
.
84
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
Figure 6: Tangential strains in the gusset at 4 days after pouring
2.1.3 Evolution of stresses in the gusset
5 participants (Team 21, Team 25, Team 40, Team 44 and Team 50) have given stresses
values in the gusset, mainly after 4, 12 and 30 days (and 10 months for Teams 21 and 50). No
experimental measure is available for the stresses.
Team 40 has provided the evolution of tangential stresses in the gusset during the first days
after concreting. It shows that the maximum tensile stresses are obtained almost 2 days after
concreting (> 3MPa in G1 and G2). This means that the cracking occurs almost 2 days after
the pouring, while the temperature decreases. Team 40 recommends not taking into account
stresses values after the cracking for early age calculation but only the stresses evolution
between the pouring and the cracking. In fact, stresses values have no physical meaning when
cracking occurred.
At four days after pouring
[Figure 7]
, 3 participants (Team 21, Team 25 and Team40) have
tensile stresses in the entire gusset (from 0,4 to 2,7 MPa). For these teams, the lower part of
the gusset is more tensioned than the upper part.
The 2 other participants have lower tensile stresses and even a compressive stress, especially
for Team 44 showing about 3 MPa compressive stress in F1 (and lower compressive stress in
G1).
85
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
Figure 7: Tangential stresses in the gusset at 4 days after pouring
2.1.4 Cracks in the gusset
The tables
[Table 1&2]
below give the experimental cracks evolution in the gusset between
the concreting of the gusset and the end of construction (before pre-stressing). These cracks
were highlighted during visual inspections of the mock-up, 5, 12 days and 8 months after the
pouring. All cracks are vertical. The two tables below synthesis the main characteristics of the
cracks evolution.
Table 1: Main characteristics of the cracks on the inner face of the gusset
Time
Intrados
total length in mm max opening in mm
spacing in
mm
number of
cracks
t0 + 5 days
4990 0,1
~1200
18
t0 + 12 days
8490 0,2
~1200
22
t0 + 30 days
wall not accessible
t0 + 8 months
no inspection conducted
Table 2: Main characteristics of the cracks on the outer face of the gusset
Time
Extrados
total length in mm max opening in mm
spacing in
mm
number of
cracks
t0 + 5 days
6325 <0,1
~1200
17
t0 + 12 days
9940 0,1
~1200
23
t0 + 30 days
wall not accessible
t0 + 8 months
16000 0,2
~1200
30
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