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Home arrow Engineering arrow Creep Behaviour in Cracked Sections of Fibre Reinforced Concrete: Proceedings of the International RILEM Workshop FRC-CREEP 2016
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Main Results

Consistency of the Experimental Loads

The following values of Fel-maxBB were measured: 31.78; 29.61; 37.69 kN (mean value: Fel-max BB = 33.03 kN). Thus, calculations lead to: Fpre_cracking = 39.63 kN and Fcreep = 19.81 kN.

A comparative study was carried out to check if these loading rates are consistent with what could be observed in a tunnel project. To do so, structural analysis using Navier’s solution and a yield line analysis were carried out on the slab used in the creep test. They led to mean bending moments of Mpre-cracking = 6.10 kN m/m and Mcreep = 3.06 kN m/m. Then, these results were compared to those of a finite element model corresponding to the detailed design of a 2D-section of the Saint-Beat Tunnel with a layer of 10 cm of FRSC and steel arches spaced at 1.5 m intervals. The corresponding geological model is mostly composed of limestone (RMR IV according to the AFTES classification) modeled with a Mohr-Coulomb constitutive law, the parameters of which are у = 26 kN/m3, c = 150 kPa, u = 35°, E = 1 GPa and t = 0.3. The medium depth of the tunnel is about 120 m and the deconfinement rate is estimated at 20 % (k = 0.80). After de-homogenisation, the results in terms of designed bending moment in the sprayed concrete layer ranged between 1 and 7 kN m/m, with a mean value of 4 kN m/m. Consequently, the loading rates considered in the Asquapro research programme are consistent with what can be observed in a tunnel project in a surrounding limestone rock with a low value of deconfinement. More detailed analyses are on-going.

Table 4 Duration of the pre-cracking phase

RSC

Type of reinforcement

Pre-cracking duration for specimens

A

B

C

BF01

Polymeric fibres

7 min

4 min

4.5 min

BF02

Steel fibres

-

-

-

BF03

Polymeric fibres

7 days

75 days

-

BF04

Steel fibres

6 min

-

-

BF05a

Polymeric fibres

25 min

2 min

1.5 min

BF06

Amorphous metallic fibres

-

-

-

WWM

Welded wire mesh

-

-

40 days

- means: the whole test

aThis is a prototype fibre, not on the market

 
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