In the spirit of ‘Best Engineering Practice’ and to show the ease with which GeniE can be used to model 3D structures, Rune Nysveen, DNV Software’s Regional Sales Manager for the Americas, and Ole Jan Nekstad, Sesam Product Manager, recently used GeniE to design their cabins in Houston and Norway respectively.

“Although it was probably not necessary to perform a full FE analysis of such a simple structure, creating my own model certainly gave me an insight into how useful the software is in the design process,” says Rune Nysveen.

A 3D model was created using GeniE, from which material lists were made for studs, timber beams, the outer panels and the internal gypsum walls. Material properties for timber were entered and beam sections were created for each of the structural members. To check the deformed shape for different structural configurations, uniform loads were applied to the roof and beams were added and removed as necessary to minimise the maximum deflections of the main members.

Once the structural calculations had been performed and the cabin design finalised, GeniE was also used to ensure good drainage of the site. The ground elevation was measured at a number of points, the coordinates of which were entered into a second GeniE model. The entire site was then modelled as a number of triangular plates, from which the drainage system was laid out to drain water away from the cabin.

“We spend much of our working life talking to customers about the benefits of our GeniE 3D modelling system, so it seemed like an excellent opportunity to use the software on a personal project to show its power and flexibility,” says Ole Jan Nekstad.

“Even though the cabin was designed by a well-known Norwegian constructor, I wanted to verify the most critical parts. The shear forces acting on the structure were calculated and compared with the design criteria. The most critical parts were the main beams supporting the roof with a maximum span of six metres. During summer, grass is growing on the roof, while it carries a huge quantity of snow during winter. When analysing for snow loading, key considerations are that depths can reach three metres and the distribution may be uneven due to windinduced drift.

The complete cabin comprises two inter-connected individual cabins. The walls of each cabin will shrink by up to 8cm over five years as the timber cures. This means that the roof on each cabin will slide relative to the connecting corridor which is not built from solid timber.

Fig. 1	Fig. 2
Fig. 3	The cottage in the mountains in southern Norway

Fig. 1 shows parts of the model created. Main roof beams are constructed from circular timber with rectangular section timber joints and wall plates supporting a water proof membrane.

Fig. 2 shows the uneven snow distribution applied. The dominant wind direction during winter is from north west (left on the picture). Combined with the cabin configuration, this leads to the uneven snow distribution shown. Beam shear forces for this loading are illustrated in Fig. 3.