Replace 90x270 with two 45x220?

[JErikss]

Can a glulam beam 90x270 be replaced with two screw-laminated glulam beams 45x220, or would too much load-bearing capacity be lost?

This will be the front support beam for an entrance roof, probably with concrete tiles, but it's not impossible that it could be a metal roof, 4m span resting on two 90x90 glulam posts. About 1.7m protruding from the house wall, about 17 degrees slope.

I'm asking only because it would be much easier to handle.

I'm also wondering what the difference is between GL28h and GL30h when it comes to posts, as I haven't managed to understand despite reading and reading...

 

[Kane]

How do you think, ask the person who did the calculation.
There will be quite a big difference in strength between 2 pieces of 45x220 vs 90x270. And it’s not linear.

 

[Peter2400]

Can you replace a glulam beam 90x270 with two screw-laminated glulam joists 45x220, or do you lose too much load-bearing capacity?

To compare the flexural rigidity of two beams, you can calculate BxHxHxH.
This gives you a figure for one beam that you can compare with another beam's dimensions.

 

[JErikss]

How do you think, ask the person who made the calculation.
There's quite a difference between 2 pieces of 45x220 vs 90x270 in terms of strength. And it's not linear.

I'm thinking what I wrote, I've heard about screw-laminated beams instead of a coarser dimension but I don't know how much is lost with that. If there's a big difference, you've answered my main question and if that's true, I won't do it. 👍

 

[Taxture]

Were you planning to make a 45x440?
Otherwise, a "limskruvad" 90x220 is obviously weaker than a 90x270...

 

[JErikss]

Were you thinking of making a 45x440?
Otherwise, a "glue-screwed" 90x220 is obviously weaker than a 90x270......

This is not my area of expertise, I must say, but I've got the impression that two separate ones become more stable than one of equivalent size. It might not be true at all, but that's why I'm asking.

 

[z_bumbi]

The glulam beams are already glued, so any advantages of gluing regular timber have already been achieved and surpassed. That is one of the reasons for using glulam.

In your case, you lose a lot of strength, but whether it's sufficient is something you or someone else will have to calculate.