Hi, Im trying to analyze some single arch beam made of Bamboo Splits. The question is how can I define this kind of custom Cross Sections (examples attached) in order to run the structural analysis?.. 
Regards,
Hi @mromanarq,
first calculate the area, moments of inertia and resistance moments of your cross sections. Then choose a cross section in Karamba3D with visually similar shape (e.g. I-Profile) and use the ‘Modify Cross Section’-component to set the area and the other properties determined for the real shapes.
For calculating the cross section properties one could use e.g. INCA2 or some similar tool.
– Clemens