Kangaroo - Activate Internal Bracing simulating bending stiffness in a structure

Hello, 

I'm a beginner at Grasshopper so apologies if the question seem basic but I've modelled the shape of my structure and I'd like to optimise the form for a best wind load performance.

I have not modelled the columns and the slabs of the building so to achieve bending stiffness I've modelled truss-like internal bracing connecting the two faces together. 

However, when I run it in Kangaroo the structure behaves as if it does not have any bending stiffness and is just a hollow box, so I'm guessing I haven't introduced the trusses to kangaroo the way i need to... Could you please give me any advice? 

Thank you in advance!

Viktoria