Dear Sir,
I have modeled a 3D concrete simple beam under two concentrated loads using ATENA 3D v5.3.4, my question about the tension stiffening of the concrete :Is the tension stiffening value =1.0 consider a reasonable value  for the model or not ?
note :
1-the concrete material name :3D Nonlinear Cementitious 2
2- the strain distribution over the beam depth at the mid span section at the integration points was linear from first step to the final  step when tension stiffening value =1.0, but the strain distribution wasn't linear and  i got a strange shape of strain distribution when  tension stiffening value = default value=0.4 and also when tension stiffening value =0