I’m creating a model of a steel hall and I encounter two main issues.
I want to use S355 as my steel quality, and think I have assigned it correctly. The calculations of N_Rd and M_Rd however display values in line with fy = 235MPa, the “standard” material. What might be the cause of this?
I use OptiCroSec to determine the necessary profiles. The component displays no errors (I thus assume that the target utilization according to EC3 is met), but when I connect the model from OptiCroSec to the Utilization component, different, higher utilizations are found. What might be the cause of this? This discrepancie is found even if the no. of utilization iterations are set high (10-50 iterations).
Another question on the topic: Does both OptiCroSec and Utilization component calculate similarly according to EC3?
ad 1.) The material S355 was correctly set for the initial model. There the material input at the Assemble-component overrides the material set at the cross sections. In the next step the cross section optimizer replaces the existing cross sections and in this way overrides the material. In case of your definition those cross sections had the default material (steel, S235) attached. One can use a cross section modifier to set the materials: Stålhall V3.2_cp.gh (310.9 KB).
ad 2.) In version 3.1.50129, the cross section optimizer does not report non-converged cross section selections. Since the optimization process is non-linear, changes in cross sections can lead to internal force redistributions, potentially resulting in overutilized elements after the final iteration. More details on this behavior can be found here. However, for plastic materials like steel, this still results in safe designs. You might try increasing the number of utilization iterations via the “Util Iter” input-plug to improve convergence.
In Karamba3D 3.1.50129, there is a known bug in the displacement optimization procedure for multiple load cases, which I am currently working on fixing. Once resolved, the cross section optimizer will also provide a remark when cross sections do not converge.