Creating a Grid with three beam directions

72kika1bar · May 16, 2019, 3:38pm

Hello everybody,

we designed a building with a big steelgrid as roof.
I tried several times to draw it in ArchiCad and failed, till my professor showed me Rhino with Grasshopper. I tried a lot especially with kangaroo, but I’m just lost at the moment.

Our plan was that there are 3 curved walls which define the bottom points of the grid. The highest point of the building is 15 meters.
I’m more than thankful for every help, how I can start.
Attached are our plans, how we want it to be.

DanielPiker · May 16, 2019, 6:45pm

If you are new to Rhino it might be good to start simple-
You could make a plane, rebuild it to get some more control points and move these to get the dome shape, then cut it with planes to get your dome

tim.stark · May 16, 2019, 7:24pm

In addition to @DanielPiker recommendation There are many tutorials on YouTube etc about truss systems. Mainly they will use a grid from surfaces UV points. Because your roof shape is not doable from a single untrimmed nurbs surface I would project the boundary on the xy plane and do the grid in 2d. Project the lines or grid points on the surface in the end. Relative item/s component is quit handy for that.

PeterFotiadis · May 19, 2019, 2:37pm

Assuming that the envelope is done via some kind of W truss (MERO KK and the likes) here’s a way via K2:

Using a closed curve (the footprint) divide and get the sequel of points (as anchors: the white ones in the pics attached) that define the areas where the envelope is grounded .
Triangulate (Delauney) a point collection inside (add the division points from 1) and get rid of the faces outside the boundary (plus get rid of the faces that have 2 naked edges or 3 naked vertices [ case: concave footprints]).
Relax the mesh by separating the naked edges and the clothed ones (the classic tensile membrane trick) plus use some unary force (Z) in order to inflate the mesh. For the blue naked points that define the openings use an OnMesh IGoal (using a mesh from lofting the boundary curve and another one due to an offset [the red, shown on ground for clarity] that is moved upwards). Spot that the blue points define naked edge collections that are inclined outwards (due to that IGoal).
Do a W truss out of the mesh (not shown in the following pics).