Proceedings of the International rilem conference Materials, Systems and Structures in Civil Engineering 2016
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- 2. Benchmark VERCORS 2015 2.1 Theme 1: early age
- 2.1.1 Temperature evolution
- 2.1.3 Evolution of stresses in the gusset
- Time Intrados total length in mm max opening in mm spacing in mm number of
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.
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 5: Preliminary results - Temperature given by participants in the gusset (G1 and F1)
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
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
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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