Interpret K-Drawing

[aktieante]

Can someone help me interpret some things on a k-drawing?

 

[Bror]

If you write what needs to be interpreted, maybe someone can help you.

 

[aktieante]

Thought to take it via email.

 

[Mats]

Can you then post it for everyone to see. That way more people can learn from it

 

[aktieante]

Wonder if the 2 HEB beams that are 6600 mm and 6650 mm Should they be at the same height as the bjällklag?

 

[imported_Byggaren]

Can't see your beams. Can you mark them with color?
__________________
Builder

 

[aktieante]

Here you might see better.

 

[imported_Byggaren]

Now they were a bit more visible.

Since the dimension is HE 220 B (not HEB 220 as the designer wrote), they are 220 mm high with a flange width of 220 mm, web thickness of 9.5 mm, and flange thickness of 16 mm and weigh 71.5 kg/m.

But I can't find anywhere how thick the floor joist should be (neither on this nor previous drawings).

However, it seems like the designer envisioned a träbjälklag c 600 of some dimension, and the easiest way is to lay them on top, unless the beams are unsightly on the floor below. In that case, it's better to lay them on the lower flange and notch for both that and the upper flange in, for example, 45x220, which then matches the height with the beams. Thus, the floor joist becomes of even thickness, and the beams are not visible on the top or bottom.

If you place the joists on top of the beams, you need to consider enclosing them fire-resistantly since the load-bearing capacity of iron/steel completely disappears at +620 degrees C.
_____________________
The builder

 

[aktieante]

Thank you for your response.
The floor structure is 220mm.
Prefer not to have them visible.

So it can be resolved by "sticking" into the floor structure in the flange of the beam.
The trusses then, do you place them over the floor structure and beams?
I think the floor structure is oriented the wrong way in relation to the trusses.

 

[R Grahn]

Let's see...
The reason the joists might appear to run "the wrong way" is simply because it is the most suitable solution when using regular K-wood. The span is simply too wide for the joists to run the other way.

It is impossible to determine at what level the steel beams should be with the drawings you have provided, but if you upload all the drawings you have, or at least a section drawing, we should be able to solve the issue for you. If it is not visible on that drawing, the easiest option is probably to call your engineer and consult him. I can certainly imagine that his intention is for them to be under the joist and then dressed with, for example, plasterboard. The reason for this is that I suspect the bearing length otherwise becomes too short for the wood to withstand the load; however, I don't have tables nearby to verify this.

Regarding the rafters, I'm having some difficulty visualizing the construction. What type of house is it? (1.5 stories/2 stories, etc.?) and what type of roof? (gable roof/mansard roof/shed roof, etc.?)

Post a bit more information here on the forum, or send me a PM, and I'll give you my address so I can take a look at it tomorrow if I have time.

Regards

 

[imported_Byggaren]

So you can solve it by "inserting" it in the flange of the beam within the floor structure.
Then the roof trusses, do you place them over the floor structure and the beams?
I think the floor structure is oriented the wrong way in relation to the roof trusses.

Yes, that's perfectly fine. Notching the top and bottom of the beams, according to the flange thickness, with a jigsaw. The support will be 105 mm deep against the web, so it will manage excellently. No anchoring is needed between the beams and the beam since the floor structure is not subjected to any forces other than those generated within the beams due to moderate bending in them.

If you post a sectional drawing so we can see the roof slope, etc., you can get an answer to that question too.

As R Grahn writes, it depends on the spacing, but your designer would likely have managed with HE 220 A beams instead of HE 220 B from a load-bearing perspective. (They weigh less and are cheaper to purchase.) H/she has probably chosen HE 220 B beams solely because an HE 220 A is 'only' 210 mm high and therefore doesn't align evenly in height with 45x220.

The alternative would have been a thicker floor structure oriented the 'right way' with glulam beams or box beams of plywood.
_______________
Builder

 

[R Grahn]

Yes, it's perfectly fine. Notching at the top and bottom of the beams, corresponding to the flange thickness, with a jigsaw. The support will be 105 mm deep against the web, so it holds up excellently. No anchoring is needed between the beams and the girder since the floor framework is not subjected to any other tensile forces than those arising in the beams due to slight bending in them.

If you provide a sectional drawing so we can see the roof slope, etc., you can also get an answer to that question.

As R Grahn writes, it depends on the span, but your designer probably could have managed with HE 220 A girders instead of HE 220 B from a load-bearing perspective. (They weigh less and are cheaper to purchase.) Probably, they chose HE 220 B girders for the sole reason that an HE 220 A is 'only' 210 mm high and therefore doesn't align evenly in height with 45x220.

The alternative would have been thicker joists in the 'right direction' with glulam beams or box beams of plywood.
_______________
Byggaren

You are probably entirely right about the support. It was just a thought that struck me in haste, as I was calculating support pressure on wall plates etc. not long ago, and was surprised by the low strength of wood. (when calculating with the new Eurocodes)

As for how the beams should be supported, I'm also inclined to change my mind here. I also reflected that the designer had chosen HE 220 B instead of HE 220 A, but completely forgot that the heights of these differ.

But as mentioned, a sectional drawing would be interesting to see.

R Grahn