Purlin roof structure may be modelled by simple 2D members, that is simply supported beams or hinged frames. However the task might be expanded and the whole scheme of the roof structure might be modelled in 3D in FEM software e.g. SCIA Engineer.
For SCIA arranging rods in 3D space on the basis of CAD drawings is easy work. What is more interesting is to introduce hinge connection to the model (every connection has 6 degrees of freedom) to imitate the real behaviour of the structure. Beside calculations of bearing capacity of each rod I also included stress analysis in connection between angle braces and a post in the project.
- EN 1995 Eurocode 5: Design of timber structures
- Nemetschek Scia Engineer
- Autodesk Autocad