SOFiSTiK Forum

I am having some issues with the cracking behaviour of the concrete.

The material I'm modelling is textile reinforced concrete with glass fibre reinforcement. I am modelling this using standard reinforced concrete shell elements but with modified stress-strain curves (based on material tests). I have calibrated this model with bending tests on the material and have found a close approximation of the behaviour (with tension stiffening beta=0.5). However, now I am modelling a more complex structure with several load stages I am having an issue with cracking. I have attached some results which hopefully show my problem.

The results (attached) show that the maximum tensile stress in the concrete is 2.40 MPa, which is well below the tensile strength of 5.08 MPa. However, the 'direction of cracks' results shows extensive crack formation at the same load. These cracks are then left permanently in the structure during the subsequent loading stages and therefore have a significant impact on the subsequent behaviour and final strength.

I am trying to find out why the program seems to be detecting cracking prematurely, and hopefully how I can stop it from doing so.