# Creating a truss system underneath a curved surface (roof)

I am a civil engineering student and currently trying to create a parametric model for a truss system for my intended curved roof structure. However, I could not figure out how to make the truss to follow the shape of the roof. I am new to Grasshopper, and hopefully, someone could help me to solve this problem. The grasshopper script and the roof model in Rhino are attached. Thank you!
Arena Truss.gh (16.1 KB)

A couple of notes:

1. Even if you attempt to cover 100% the arena you sould deploy trusses in a “radial” so to speak way. Cover the hole with a net of cables instead of attempting to bridge big spans with metal LBS. Avoid at any cost retractable solutions since these require a team of pros in 3 different engineering disciplines (and no R/GH). As we do in classic membranes rather try a saddle type of topology (unless you want a flatish roof for some reason).
2. It’s advisable to mastermind trusses with “thickness” (say a MERO KK system) otherwise you should use elephant sized beams/connections etc etc. Use cables as well: they can deal with forces in a rather elegant AND cheap way (but require masts). This means that - in a way - every contemporary stadium roof is a tensegrity system. Connect trusses with some sort of inner ring: this stabilizes the LBS with the most rational way (and allows access to lighs, sound, screens etc)
3. It’s advisable to mastermind the trusses and the whole LBS approach AFTER fixing the exact type of roof (i.e. acrylic panels? opaque ones? a combo? (see London Olympic stadium), tensile membranes? etc etc).
4. It’s rather impossible to outline any solution that has some sort of relation with real-life (even within an Academic perspective) without extensive use of code.

Here’s 3 indicative snapshots on that matter (obviously there’s 1Z++ other solutions possible but the principles are rather clear).

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Thank you for your tips. However I’m trying to create a truss system for an indoor arena, and as such there is no “hole” at the centre of the stadia.

Word hole is used to indicate the remaining NOT covered (via the radial trusses) portion. This means: create an outer LBS (kinda a “ring”) and then use cables to support the roofing solution/portion that deals with the hole.

BTW: On the other hand and if you are a novice on things like these … the trad solution is a MERO KK on some sort of template roof Surface (or BrepFace if you are brave). Rational, light, economical and made in Germany (the best of the best of the best etc etc). You should do something with the hole mind (use cables).

I get what you mean, however, the arena that I am designing has no roof openings, it is fully covered, hence the radial truss system cannot be applied. It should look like this, for example: London Aquatics

The trend these days is towards lighter (and smarter) truss systems/roofs regardless if the roof is closed or not (plus pneumatic systems that are 100% suitable for a closed stadium/arena: find a friend who has contacts with Birdair).

If thin air makes you nervous see this for instance (minus the retractable parafernalia):

But even the above is a bit Gothic … this is the way to cut the mustard these days:

Other than that a real-life truss is 99% about node design: this is not achievable - by any means - with R or GH.

Other than that engineering is always a bottom to top procedure (i.e. I do something having fully mastered the details/nuts/bolts/etc ) … meaning that you’ll need things the likes of CATIA/Siemens NX etc etc.

Moral: assume that we have to do wild things in the Isle of Man (proper roads, no speed limit). Bring any sports car that you can imagine. Me? I’ll use my Ariel Atom.

BTW: If you are after the most rational way and you don’t like cables … just do a classic MERO KK solution on a suitable surface over the arena. The shown has a sin distortion with regard W (i.e. is thick in the middle, thin in the lips).