I am currently considering different designs of columns to support an HEA beam. Due to space constraints, I would prefer to place a steel beam in a wall (which is about 8 cm thick).
However, I am stuck in my attempts to calculate the strength of a VKR 80x40x5 column which is 2.3m long and bolted at both ends.
The load on the horizontal HEA beam consists of the bearing force from 2 rafters that end at about 1/3 of the roof slope, i.e., only 1/3 of the roof slope will load the structure roughly speaking. With snow zone 2.5 and a rough overestimation of the roof area + its own weight, I get the load to about 20 kN per rafter. The columns should thus carry 20 kN each without buckling.
Beam tables provide a radius of gyration of 27.4mm and 15.5mm for VKR 80x40x5 (does that seem reasonable?)
This would give a slenderness ratio of 89 if calculated for a fixed-fixed beam (2300*0.6/15.5).
Is this sufficient? Or have I calculated completely wrong? What more should I check?
Please, help someone who has misplaced their PDF with formulas and is experiencing bad search engine karma trying to find the formula collection again.
Thank you! Those were the tables I was (hopelessly) looking for.
From page 76 (in the 2018 edition) it seems to me that for the buckling length 2.1m, a VKR 80x40x5 can take 105kN without support in the weak direction.
That must surely be enough to support the equivalent of 5 m2 of roof with a 34-degree roof pitch in snow zone 2.5.
Load from the roof: = [self-weight of the roof (concrete tiles) = 0.6kN/m2 + 2.5 kN/m2 snow load] * 10 m2 (exaggerated) = 31 kN distributed on 2 pillars.
You do not need/should not invent your own safety factors for the loads. Search for load combination STR 6.10b, and you will get the safety margin according to the standard if you follow it.
Can two roof trusses be offset with a wooden beam?
You don't need/shouldn't invent your own safety factors for the loads. Look for load combination STR 6.10b to get the safety margin according to the standard if you follow it.
Two trusses should be able to be transferred with a wooden beam?
Thanks for the remark, I completely agree with you. The purpose of my calculation was to assess the reasonableness of a solution, and my memory from my latest calculations (a long time ago) was that a rectangular VKR 80x40x5 should hold more than well.
Now that I know at least that the solution can work space-wise, I'll calculate more properly according to the rules of the art.
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