Étude du comportement en flexion et à l'effort tranchant de poutres précontraintes en BRF

The combine use of SFRC and pre-tensioning seem very promising, however it isn't been greatly studied, especially for the specimen of important height (h>750 mm). This master thesis focuses on the flexural and shears behaviour of pre-stressed SFRC beams. This study is based on an experimental program including nine beams made of the same SFRC (80 MPa – 1 % of fibres). Five of them were tested in bending and the other four were tested in shearing. All these beams have the same geometry, only their reinforcement is different: number of strands, presence of passive reinforcement, and presence of stirrups. Also, an important campaign of characterisation experiment was conducted in order to obtain the compressive capacity and most importantly the traction behaviour of the material. Three-point bend tests on notched beams were conducted and also bend test on centrally loaded round panels supported on three symmetrically arranged pivots and subjected to a central point load. The latter allowed us, through inverse calculation, to obtain the constraint vs. crack opening curve of the material, which a fundamental characteristic of the SFRC and necessary for numerical analysis. Numerical models, EPM3D on ABAQUS and AIS, for each tested beam have been validated, in order to be able to predict the behaviour of pre-stressed SFRC structures. The results of the numerical simulation of the bend and shear test are very satisfying.