Modelling a simple RC Beam in ABaqus 1

[njh1987]

Hi,

I have been trying for a few months to model a reinforced concrete beam in abaqus and have had very little success. I was hoping that I could describe how i have attempted to tackle the problem and someone could provide some 'tips' or suggestions as to how i can improve the model.

Parts:
The beam has been modelled in full in 3D. I have partitioned the beam horizontally in two locations where the rebar is located. It has global seeding size of around 20 and meshed with standard settings for 3D Stress (C3D8R). It has also been set a solid homogeneous (Plane strain/stress thickness=1) section assignment

Two shell parts have also been created which comprise the compression and tension steel rebar. Each part has been given a surface section assignment with rebar layer properties. The parts have been given a coarse surface mesh.

Materials:
The Steel rebar is given plastic and elastic propertie, E=200000(N/mm2) and yield stress is 500.7 (N/mm2) with a plastic strain of 0.

The Concrete smeared cracking model is used to define the properties of concrete. compressive stress and plastic strain values used are 15, 0 to 26.4, 0.0015. failure ratios 1.16 and 0.086, shear retention rho_close=0.4, eps_max=0.0015. Tension stiffening 1,0 to 0, 0.002. Elastic properties: youngs modulus 26000, poissons ratio 0.2.

Assembly:
Each of the three parts are instanced (dependents) and then edge to edge constraints are applied to place the rebar in its appropriate locations.

The rebar is also assigned an embedded region constraint where the embedded region is the two rebar parts and the host region is the whole model.

Steps:
A static riks step is used to apply the load with non linear effects taken into account

Boundary Conditions:
On the left hand side, a hinge support is simulated by setting U1=U2=U3=0 and on the right a roller support is simulated, U2=0.

A Displacement of -100mm is applied along two lines on the top of the beam.

Results:

After running the job, it either gets past a few increments and says "Too many attempts made for this increment" or it will finish the analysis and give a deflection of around 3-4mm with a load of 20kN.

I would really appreciate any input anyone can give me and if you need any more details let me know!

Thanks,

Nick

 

[looyongabaqus]

hi nick,

I am modeling a RC beam-column connection instead. I am using Abaqus Standard. I used CDP for my concrete and beam elements for my reinforcement. The reinforcement is embedded into the concrete element in the interaction module.

As for the load step, I am using static-general but i use Automatic Stabilization and Use Damping from previous general step. Next i make the minimum incrementation size really small, ie 1E-09.

My model is able to complete running but I am getting very small deflections. Is that what is happening to you too?

Cheers,
Joseph