Universal beam question

[tony1851]

looking at the SE calculations

Roughly speaking, strength and deflection decrease exponentially with depth. So a beam twice as deep with be four times as strong.

Hopefully, someone will be along soon to take the shovel from you before you go any deeper.

 

[tony1851]

Sigh. On the basis of the facts now in your possession, would anyone like to agree or disagree that the beam sizes and spans that have been suggested might be possible? Bearing in mind that a SE will be involved so I'm not actually going to remove or build anything based solely on your advice.

On those spans and assuming a normal flat roof loading, any one of 152 x 89; 178 x 102; 152 x 152 x 23 or 30 would almost certainly do.
Deflection and lateral buckling will be the determining factors and your SE will check for those.
(Don't be surprised if your SE comes up with a beam larger than these; this is usually just to cover themselves 110%, but make it clear from the outset that headroom is a primary concern, and see if they suggest alternatives).

 

[geraldthehamster]

On those spans and assuming a normal flat roof loading, any one of 152 x 89; 178 x 102; 152 x 152 x 23 or 30 would almost certainly do.
Deflection and lateral buckling will be the determining factors and your SE will check for those.
(Don't be surprised if your SE comes up with a beam larger than these; this is usually just to cover themselves 110%, but make it clear from the outset that headroom is a primary concern, and see if they suggest alternatives).

Thank you! That's all I wanted to know.

Now everyone can go back to arguing about who knows anything about structural engineering. At least I admit that I don't.

Cheers
Richard

 

[tony1851]

Just had a thought - you can notch the joist-ends where they bear on the beam. Depending on the depth of the joists, it is often possible to cut 25-50mm off the underside, enabling you to get the beam up higher.

 

[geraldthehamster]

Just had a thought - you can notch the joist-ends where they bear on the beam. Depending on the depth of the joists, it is often possible to cut 25-50mm off the underside, enabling you to get the beam up higher.

That's well worth knowing. Joists are 170x70.

Does bolting through the top flange into the flat roof joists count in any sense as lateral restraint?

Cheers
Richard

 

[PaulUszak]

Thank you! That's all I wanted to know.

I'm sorry Richard, this is how you size /budget a project? From some anonymous geezer on the internet? You probably realise that those UB/UC sizes above have a 250% range of strength /cost. The beam depth seemed of importance from your post, and some people were trying to help. I admire your Chutzpah. Good luck.

 

[geraldthehamster]

Yes, I'll just Klick'n'go

 

[PaulUszak]

Ooh! It had to happen one day. Congratulations, you're my first stalker. You're not going to steal things from my washing line are you ?

 

[geraldthehamster]

Not at all, just checking the source of your expertise in structural engineering and building control, rather than taking advice from some anonymous geezer on the internet.

 

[jeds]

Good suggestion by Tony. Maybe ask your engineer to calculate both but Steel sections are sold by weight so a 152 23kg column section will only cost a tiny but more than a UB.

ps. when finding an engineer try to get one that has some real experience - I think you can see what happens when you get one blinded by theory.

 

[geraldthehamster]

Good suggestion by Tony. Maybe ask your engineer to calculate both but Steel sections are sold by weight so a 152 23kg column section will only cost a tiny but more than a UB.

ps. when finding an engineer try to get one that has some real experience - I think you can see what happens when you get one blinded by theory.

Thanks. I have confidence in the SE I've used previously, so I'll be going to him.

Cheers
Richard

 

[^woody^]

..... SE I've used previously, so I'll be going to him

Can someone explain to me the whole point of this thread?

 

[geraldthehamster]

Can someone explain to me the whole point of this thread?

 

[PaulUszak]

I have confidence in the SE I've used previously, so I'll be going to him

Can someone explain to me the whole point of this thread?

Seconded. Perhaps woody's time and others' could have been put to better use if you hadn't posted in the first place. Good people have replied 43 times to what seems now like a fake question.

 

[geraldthehamster]

Seconded. Perhaps woody's time and others' could have been put to better use if you hadn't posted in the first place. Good people have replied 43 times to what seems now like a fake question.

What a rude man. Actually most of the answers have been very useful, as is often the case.

I'm sorry if you haven't enjoyed it, but it hasn't been for your benefit.

Cheers
Richard