hello everyone
I'm a student from Belgium and I need some help for a construction exercise...

We need to design a structure for a roof of a big storage place
it's 42x42m (take a look at the pictures)
There is 1 bearing concrete wall and 5 possible points where we are allowed to place a column....
We are not allowed to construct one big 3D framework, because that would be a solution that's too easy and not efficient enough...

this is what I thought: (check the pictures)

To cross the 42m gap, I thought of an Arch, to which 2 frameworks are connected by cables (everything in steel).
This way, the height of both the frameworks can be reduced
(rather than just placing 1 or 2 frameworks of 42 m)
and there is a central region that can be enlighted (by filling the arches in between with glass)

Nevertheless, we there's also a restriction in height
The roof must start at least at 9m and cannot be higher than 15m
this means the arch can only be 6m high....

Would this be a problem for the columns (120x120cm = max. allowed) to take the horizontal 'arch' loads?
by the way, the column on the left is allowed to be larger (240x120, as can be seen on the plan)....

Any tips?
btw, the large rectangles need to be frameworks, I didn't draw them correctly yet, it's only a quick sketch-idea

thanks!

plan
it's only the rough structure and needs to be detailled further by placing extra connections between the 6m regios

elevation
the heights are the maximum allowed ones

If I understand correct the main wall can be centrally placed ?

If so I would think 2 portals Y shaped with maybe rod ties between Y & rods to sides would be economic .. (sort of) M .. then for the hell of it I would try to push that idea further maybe with shells or a hybrid of shell & portal & rods

Ask the reasons for the imposed design restrictions

no, the main wall can not be moved
it is on the side of the hall and needs to stay there
this means there is a region of 42x42m without any point where a wall or column can be placed

the restrictions are only from the teacher, to make the exercise a little harder...

Your current solution has a major flaw. Your arch has nothing to resist a force pushing outwards. (there is a horizontal and vertical component of the force in an arch) You need member in tension to resist that force. In other words your arch becomes a truss.

The structure, as it is shown, seems to me a little unstable, and not only by the arc support reactions . Other forces in the transeversal sense to the arc also take place that are not seen sufficiently balanced. It seems to me, that
a better solution would be to use tho trusses put upwards (in the same position that the arc) in whose inferior member ,the lateral beams of each section of the roof could rest.

hi,
thanks for answering
I got another question: what is the english word for this kind of profile? (see picture) ?
edit: I found out it's a cellular beam, or castellated beam
Does anyone know where to find dimensions for it?

I want to use this kind of beam for a length of 18m
how high will it be? 0.5m? 1m?
it only needs to support roof coverage

thanks