Dear José Álvarez-Pérez

This all depend all the fiber or reinforcement that contains with the concrete with varying reinforcement volume fractions in the tensile tests. The results you will get the specimen with high reinforcement or fiber volume fraction exhibited high direct tensile strength and improved brittleness. fiber has high energy absorption capacity.

https://doi.org/10.3390/ma12203335

Dear Manik Mahali

Thank you very much for your answer.

But I think that the question is refers to the plain concrete specifically.

Dear José Álvarez-Pérez

Thanks for your interesting question and related discussion. I have read an pre-print version of the article by Pulatsu B, et al. , titled "Simulation of uniaxial tensile behavior of quasi-brittle materials using softening contact models in DEM" on RG. Hope this article is helpful as it contain a bundle of knowledge about the direct tension experiments of plain concrete.

Best regards

Article Simulation of uniaxial tensile behavior of quasi-brittle mat...

Dear Mohammed Hussein j. H. Al'Atia

Thanks a lot for your recommendation

In the recommended article, “Simulation of uniaxial tensile behavior of quasi-brittle materials using softening contact models in DEM”, the DEM was validated by experimental results from Hordijk (1991).

Reading the article, and the experimental report result of Horik’s work from 1991, we have the following doubts:

1) The elapsed time in the experiment between the peak stress (3.3 MPa approximately) to rupture stress (0.15 MPa approximately) is not reported.

2) Is it possible for plain concrete to have a maximum displacement in direct tensile over the 0.10 mm?

3) Is it a real or academic graph of the experiment?

The experimental tests analyzed carefully, make us think that it seems more an expected result than a physical result of the material.

Dear José Álvarez-Pérez

Thank you for your kindly feedback.

It is clear that there is experimentally post-peak behavior present with a defined limit on displacement. This limit is highly related to the size and shape of the applied aggregates.

The fracture energy considered as the area under the post-peak curve; it depends on the test specimen shape and geometry.

Now, it is clear that the post-peak curve and fracture energy are not a unique material property.

Best regards

http://archives.njit.edu/vol01/etd/1980s/1988/njit-etd1988-012/njit-etd1988-012.pdf

Maybe the fracture energy of quasi-brittle material has a significant effect on structural behavior only when there is reinforcement. Due to the ductility increment, the material interaction in post cracking increases in terms of deformation.

José..Programa Video Conferencia y te Explico.. Todo

1) Yes, but specimen's length must be roughly smaller than wu.E/ft

wu - ultimate crack opening (see e.g. Hordijk's law);

E - Young's modulus

ft - Tensile strength

2) No. As mentioned above, it depends on specimen's length.