Yeah.. compressive stress and tensile stress are two opposite things.(eg. + And -)

First of all these are the part of stress, as we know ..

Elasticity (E)= stress / strain

From this you can easily find that when stress (compressive or tensile) are varies than elasticity is also varies.

Firstly, thanks for your response But as you can see in this article the parameters are constant But other parameters change For example, compressive strength varies but tensile strengths are constant

Mohammad Rostami

Nice work

I am working on fiber reinforced concrete, but for the load carrying capacity

Don't worry ,, firstly you have to read a finite element method design book .. then all doubt will clear ..

You have to know one important point=

Tensile strength of concrete is nearly 10 % of compressvie strength of concrete..

Your parametric study is fail ...

I suggest you , you can fix the strain and see the variations about stresess and size of section