I have read quite a few posts here in the forum, but I haven't completely figured out how to safely size a beam for an opening in a load-bearing outer wall. I understand that there are a lot of skilled and knowledgeable people here on the forum. I sincerely hope someone can help me. I have tried to calculate myself, but I am extremely unsure if my result can be correct.:S I have a sliding door section that is 3.5m long to be installed. Single-story house with a basement. Living in Gothenburg. According to calculation programs at Moelven, I have a load of 14.4kN. A glulam beam with dimensions 115x270 is recommended. Deflection will then be 9mm. Due to space constraints, I want an HE-beam. I have calculated according to a formula taken from the Karlebo handbook to get deflection (f):
f=PxL^3/48xExI
calculating on an HE100B:
1400x350^3/48x2100000x5000=0.119cm
Can this really be correct??? 1mm deflection!!! I only have a couple of days until the carpentry help arrives. I feel a slight panic
The roof load according to Moelven's Beam Program:
0.9kN/m2, concrete tiles/insulation/internal cladding
house width 6m
opening 3.5m
this gives a dimension post load of 16.3kN (I got 14.4 when uninsulated - wrong choice by me earlier)
...aha...this should mean a 32kN roof load, right?
new calculation gives me 3mm.
I don't think you're using the right formula.
But I don't have my formula collection available, so I can't check what the correct formula for simply supported on two supports with distributed load is.
3mm is not a reasonable deflection for an HE100B with a 3.5m span.
Then I wonder if your data takes into account snow and wind loads?
From what I understand, loading zone 1.5 (Gothenburg) is included. However, I am not clear on what 16.3 kN column load means. I interpret it as the load on a column at each end of the beam. That should correspond to a 32.6 kN point load, or am I misunderstanding the whole thing:x Hmmm... 20 years since I was calculating this kind of stuff
As I understand it, load zone 1.5 (Gothenburg) is included. However, I am not clear on what a 16.3kN column load means. I interpret it as the load on columns at each end of the beam. Then it should correspond to a 32.6kN point load, or am I misunderstanding this? For point load F, you have F/2 at each column.
I must thank you for taking the time Gabbe1! d^_^b
The reason I assumed widespread load is that over a distance as long as 3.5 meters, I assumed that several roof trusses would load the beam.
If you calculate with a point load of 32kN in the middle of the beam, the deflection would be more than 3cm.
IF the 32kN as total load is correct, I would have chosen, for example, a HE160A and gotten a deflection of 5mm.
But I would definitely confirm that load with a structural engineer before ordering the beam.
I must have a power of ten error somewhere, because I'm getting a deflection of 3mm, not 3cm...
I should probably follow your advice and let a structural engineer calculate it all.
Hmmm....then it will probably be an IPE220...moment of inertia at 2772:wow:
should be 3mm deflection under distributed load IF the roof load is just under 33kN...
I would also like the same help, I have used an online program to calculate which beam and pillar I should have to replace the load-bearing concrete wall that will be removed.
You probably need to specify which parameters (lengths, widths, etc.) you have used. I can't figure it out from the image so that it matches.
Hello!
The width of the house is 7500mm.
The length of the opening should be 3800, as I have written. The wall itself is 3540, but then I also counted the pillars, which is why I added that.
The floor height is 2300, but I wrote 2500 to give a little extra here too.
There should be 2 pillars, and the opening should be on the first floor. On the second floor, there is a kitchen and bathroom, but the kitchen will be converted into a bedroom.
There is something wrong with your calculation that I cannot explain, but if you choose the dimensions you have come up with, you have at least not undersized. Otherwise, I would suggest 90x360 for the beam. The columns handle the load brilliantly, but that is also the minimum dimension.
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