Hello everyone!
I am going to build a loft in part of a machine hall. Since I don't want a lot of pillars and such in the way, I plan to use steel beams to support the construction. I have done some calculations myself, but I'm not 100% sure if I've thought it through correctly since I'm not trained in the field. The goal is not to use larger beams than HEA/HEB 220 to avoid losing ceiling height.
Some measurements etc.:
Longest beam span = 6250mm (the other is 5850mm so I'm only calculating on the longest)
total area of the loft = 52m2
length of C24 wooden beams 45x220 = 3912mm (these will be fitted into the beam)
250kg/m2 of distributed load (in reality, the load will be lower, but it feels safe to calculate with this)
I hope the construction is clear from the image.
Am I right in thinking that the middle beam will carry 1/2 of the total weight and the wall + outermost beam will each carry 1/4?
Anyway, I've calculated half the load on one beam and came up with the following:
HEA220
Stress in the beam = 103 MPa
Total deflection 19mm
which gives a ratio of 1/328
HEB220
Stress in the beam = 72 MPa
Total deflection 12.7mm
which gives a ratio of 1/492
According to what I've found, it works well with either, although an HEB beam would "feel" better. Am I correct in my calculations and reasoning, and can I possibly go down in size to HEA/HEB 200? I would appreciate if someone could help me.
Thank you in advance!
I am going to build a loft in part of a machine hall. Since I don't want a lot of pillars and such in the way, I plan to use steel beams to support the construction. I have done some calculations myself, but I'm not 100% sure if I've thought it through correctly since I'm not trained in the field. The goal is not to use larger beams than HEA/HEB 220 to avoid losing ceiling height.
Some measurements etc.:
Longest beam span = 6250mm (the other is 5850mm so I'm only calculating on the longest)
total area of the loft = 52m2
length of C24 wooden beams 45x220 = 3912mm (these will be fitted into the beam)
250kg/m2 of distributed load (in reality, the load will be lower, but it feels safe to calculate with this)
I hope the construction is clear from the image.
Am I right in thinking that the middle beam will carry 1/2 of the total weight and the wall + outermost beam will each carry 1/4?
Anyway, I've calculated half the load on one beam and came up with the following:
HEA220
Stress in the beam = 103 MPa
Total deflection 19mm
which gives a ratio of 1/328
HEB220
Stress in the beam = 72 MPa
Total deflection 12.7mm
which gives a ratio of 1/492
According to what I've found, it works well with either, although an HEB beam would "feel" better. Am I correct in my calculations and reasoning, and can I possibly go down in size to HEA/HEB 200? I would appreciate if someone could help me.
Thank you in advance!
Last edited:
Best answer
You are absolutely in the right ballpark when it comes to your calculations. HEA 200 is not sufficient, however, HEA 220 and HEB 200 are. I would still choose an HEB 220, because it is a primary beam and the deflection adds to the secondary beams of wood. 3912 mm is on the longest side for the secondary beams concerning the deflection. You should screw and glue a chipboard on top of these to get an acceptable result.
Thank you for the reply!
That's good to know. What is less good is the price of an HEB 220 beam, but quality comes at a cost. It's going to be screw-glued chipboard, and I will also add a mid-span support and use cc400 for the rafters. Then the beams against the walls will also be screwed in place and various other attachments around the stairs, etc., but that's not something to include in the calculations.
That's good to know. What is less good is the price of an HEB 220 beam, but quality comes at a cost. It's going to be screw-glued chipboard, and I will also add a mid-span support and use cc400 for the rafters. Then the beams against the walls will also be screwed in place and various other attachments around the stairs, etc., but that's not something to include in the calculations.
A spacing of c/c 600 mm is sufficient. If you used glulam instead of steel, you could achieve it at half the cost of the steel. However, the dimensions would then be more like 190x450 mm.
If I remember correctly (and maybe I don't??) the middle support in such a construction carries just over 60% of the total weight.T Thridel said:
Maybe it doesn't make much difference for your construction, it just struck me when I read the post.