Reinforced concrete beam 2D model nonlinear analysis
I have been working with ANSYS mechanical apdl for few months now and I'm modeling reinforced concrete beam with two predifined cracks. Beam length - 2,4 m, heigth - 0,244 m, width - 0,112 m. Reinforcement area - 3,2 cm². Beam has two supports, first constrained in y and x directions, second only in y direction. Beam loaded with two concentrated loads at 0,8 and 1,6 from beginning of the beam. (I attached beam scheme)
I chose 2D plane model and I'm using PLANE182 element type.
For concrete I chose cast iron material model, where I putted stress-strain relationship for compression and for tension. (attached stress-strain relationship diagrams)
For steel I chose multilinear isotropic hardening model. (attached diagram).
I modeled cracks by deleting specific number of elements (attached picture, crack heigth I get from analytical calculation).
For analysis options I chose small displacement static, 20 substeps with aytomatic time stepping, convergence criteria by default.
When I run nonlinear diagnostics, my calulation doesn't converge and I get problem in concrete tension zone, between cracks (attached Newton-Raphson resudual force diagram). in elements events, status of failure criteria in elements, it shows numbers in plastic strain.
What can I do to remove plastic strain limits or anything elso to help to converge solution? Thanks in advance.