Steel beam 9m span?

[attefall]

I am planning to build an extension and want a large 9m glass section on one wall. The roof will have a roof terrace, so additional weight will be added, but it's in the southwestern tip of Skåne, so snow load zone 1. I would prefer to achieve this without support to have a large opening in the middle. Could anyone do a quick calculation on what dimensions of beam we are talking about here? And if a vertical beam in the middle was required, what dimensions of beam could one get away with then?

Thank you in advance, all wise ones!

 

[justusandersson]

The combination of a balcony and a glass section is a challenge. A beam without support from a pillar in the middle is probably not a realistic solution. It would require a beam of the type HEA 360. It weighs over a ton and costs nearly 30,000 SEK.

 

[attefall]

The combination of balcony and glass section is a challenge. A beam without support from a pillar in the middle is probably not a realistic solution. It would require a beam of type HEA 360. It weighs over a ton and costs nearly 30,000 SEK.

Thanks for the answer, I assume it's the deflection that's the problem? If we go with HEB, what dimension are we talking about then? And if one were to place a pillar in the middle, how much smaller of a beam would be sufficient?

 

[prototypen]

Why not place 2 supports a quarter of the way from the ends, then you get the middle free.
You can anyway only open half.
Another advantage is that the middle piece with the longest span gets fixed ends.

Justus can probably calculate on 4.5 meters with fixed ends.

Protte

 

[attefall]

Why not place 2 supports a quarter in from the ends, that way you keep the middle free.
You can only open half anyway.
Another advantage is that the middle section with the longest span will have fixed ends.

Justus can probably calculate 4.5 meters with fixed ends.

Protte

I've considered that too, but it means the support beams have to be parallel with the glass section. I wonder if it's possible to do that considering the width?

EDIT: I might be missing something, but I'm thinking that the facade section is just over 200mm deep, which doesn't leave much room for a support beam if both are to be under the steel beam above?

 

[prototypen]

Does the beam have to be at the very end then?

Protte

 

[bossespecial]

A bit like it's mentioned, there's no problem pulling in the beam somewhat so that the columns end up inside the section. Have you thought any about the roof structure, it looks like it might be a bit tight to achieve the heights according to the Elevation?

 

[attefall]

Does the beam have to be at the very edge then?

Protte

As mentioned a bit, there's no problem with pulling the beam in a bit so that the pillars are inside the section. Have you given any thought to the roof construction? It looks like it might be a bit tight to get the heights right according to the elevation?

Somehow I thought the beam had to go directly above the facade section, but maybe that's not the case when I think about it more.

The roof will probably be some kind of steel construction overall, but the engineer is working on sketching it out. But I would really like to get a bit more input from others on these critical parts.

 

[prototypen]

If the beam is positioned further in, it is possible to weld onto it for support of whatever is above the glass section.
You also make some inward construction that connects with the floor structure as a counterweight so the beam doesn't topple over.

Protte

 

[justusandersson]

I think you've received many good points. It's much better for several reasons to set two columns, each 1/4 of the distance from the corners. Likewise, to place the beam and column slightly set back from the façade. You must study the section through the extension so that the elevations are correct. The floor joists need to be about 90x225 in glulam or HEA 120 in steel at c/c 600 mm. There's no significant advantage with steel here since there still needs to be space for insulation. Waterproofing and slope (i.e., pitch) are aspects that must be considered in time.

 

[attefall]

Thank you for all the answers, I will consult with my designer according to your suggestions!

I have also seen that there are facade sections where the mid-joints, right at the place where you suggest beams, are reinforced. Load capacity of 10kN, can any of you put this figure into context? And does this have any decisive significance?

 

[justusandersson]

Vertical load-bearing structures are commonly referred to as columns. Column loads are rarely an issue unless the columns are very tall. For instance, an unsupported HEA 100 column can handle a central load of about 300 kN.

 

[attefall]

Vertical load-bearing structures are usually called columns. Column loads are usually not a problem unless the columns are very tall. For example, an unstayed HEA 100 column can handle a centric load of about 300 kN.

Ok, but in that case, doesn't 10kN sound like very little? But maybe it's enough?

 

[prototypen]

10 kN corresponds to one ton.

Protte

 

[useless]

Is it possible to come off more easily if you separate the floor structure from the windows so that you can allow a slightly larger deflection of the floor structure without affecting the window section?
Maybe not entirely simple from a construction perspective, but a thought nonetheless...