Hello

I’m having trouble with my Abaqus model.

I’m modelling a concrete cylinder under eccentric compression (150 × 300 mm), confined with PBO-FRCM.

Already at the stage of the model without strengthening I get about 20% lower interaction capacity (force-moment). The axial force itself is about 12% lower compared to the experimental results. The model seems quite simple, and I don’t understand where this discrepancy comes from.

I’m using the Concrete Damaged Plasticity (CDP) model with the default parameters. The dilation angle is set to 40 degrees.

The load is applied through a reference point and a Rigid Body constraint.

An additional piece of information is that the problem most likely arises from the fact that the stress–strain relationship (determined from the stress and strain distributions along the height of the cross-section) changes in the final stage of the element’s behavior. The figure below shows these relationships for successive step times. The dashed line represents the introduced relationship (according to EC2). It can be seen that in the final stage of behavior (step time 0.475), the stresses at the same strains decrease. What could be the cause? Refining the mesh does not change anything. Likewise, changing the dilation angle from 40° to 30° has no effect.

Thanks in advance for any help!