RSJ Spacers - Are they needed?

[Dereekoo]

If helpful pictures added.

Chocolate fireguards spring to mind

 

[sxturbo]

If helpful pictures added.

I'd be putting spacers in that,

The spacers are so the beam doesn't flex when pulled tight, (and it does trust me, put a dial gauge on it then tighten it)

Over time the metal will relax and the bolts will become loose, because they are not bolted solid against something.

Although now their in place the chances of them then flexing to a degree where the house will fall down is pretty remote.

 

[Dereekoo]

I'd be putting spacers in that,

The spacers are so the beam doesn't flex when pulled tight, (and it does trust me, put a dial gauge on it then tighten it) The web or the beam in the Y - Y direction ?

Over time the metal will relax and the bolts will become loose, because they are not bolted solid against something. Does that mean all the suspension bridges cables will start expanding/drooping and pre tensioned lintels will fail after a time ?

Although now their in place the chances of them then flexing to a degree where the house will fall down is pretty remote. Probably non existent unless the SE has got his calcs totally wrong

 

[blup]

Let us know how you resolve this in the light of the different replies. The LABC website, and its contributors, has its own take:
https://www.labc.co.uk/news/beware-don’t-just-bolt-your-beams

Blup

 

[John Stanley]

Hi all,

Thanks for the responses.
SE has recommended welding 10mm steel plate to the underside of the steel beams. Although this is the same SE firm commissioned by the builder who forgot to add a point load to the beam calcs.

I have also reached out to a friend of a friend who is an SE. He said that as the flanges are butted he would recommend a 100mm of 4mm weld be run along the bottom flange of the beam at each bolt position.
(I'm guessing he is referring perhaps to stich welding, will ask him to clarify).

Will be sure to post once we've come to final conclusion on how to remedy. That said, the beams have been up a few months and no movement yet.

 

[tony1851]

Yes, spacers between steel beams create load sharing and noggins deal with deflection by the same principle. Not beliefs, facts.

And for others reading, if you go to good steel suppliers, they weld the spacers on to one beam around the holes they drill for the bolts. Prevents messing about with them, or dodgy builders not fitting them.

Dereekoo is correct; tube spacers don't enable the beams to 'work together'; in fact connecting beams in that way is specifically forbidden by BS5950. Each beam should be capable of satisfying bending and deflection on its own.

 

[tony1851]

Hi all,

Thanks for the responses.
SE has recommended welding 10mm steel plate to the underside of the steel beams. Although this is the same SE firm commissioned by the builder who forgot to add a point load to the beam calcs.

I have also reached out to a friend of a friend who is an SE. He said that as the flanges are butted he would recommend a 100mm of 4mm weld be run along the bottom flange of the beam at each bolt position.
(I'm guessing he is referring perhaps to stich welding, will ask him to clarify).

Will be sure to post once we've come to final conclusion on how to remedy. That said, the beams have been up a few months and no movement yet.

If the beams have been up a few months, why bother? The solutions offered by your SE and the 'friend of friend' are also pointless, but they make you think something 'positive' has been done.

 

[^woody^]

Dereekoo is correct; tube spacers don't enable the beams to 'work together'; in fact connecting beams in that way is specifically forbidden by BS5950. Each beam should be capable of satisfying bending and deflection on its own.

Unless two beams are designed to work as one beam

 

[jks7492]

Unless two beams are designed to work as one beam

If two beams were designed to work as one they would need more than just a few bolts and spacers.

Simply bolting the webs of two beams together at 1.5m centres isn’t a sufficient way to share the load between beams.

 

[noseall]

If two beams were designed to work as one they would need more than just a few bolts and spacers.

Simply bolting the webs of two beams together at 1.5m centres isn’t a sufficient way to share the load between beams.

I would agree. I can't imagine a few bolts and some poxy tube will do any good when one leaf is loaded with 100 tonne and the other 5 tonne. And Woody's analogy using floor joist solid bridging as a comparison is flawed because the external faces of the beams are unrestrained and can flex outwards unlike a solid bridged floor joist array - plus only the beam centre is being pulled in.

I like the idea that the flanges are touching. At least you can crank up the pressure on the bolts knowing the beams are going to behave.

 

[^woody^]

There are no flaws in the floor analogy. But there are some spacers in peoples beam knowledge.

 

[tony1851]

The final word.......

 

[jks7492]

The final word.......

Also covered well in SCI P360 - specifically has a section covering pairs of beams supporting cavity walls and the requirements to achieve load transfer between beams.

 

[Dereekoo]

There are no flaws in the floor analogy. But there are some spacers in peoples beam knowledge.

Thats cos people don't understand rigid,semi rigid or pin joints be it in wood or metal

 

[Dereekoo]

The final word.......

Being devils advocate Tony what if the beams are designed with no lateral constraint in mind, is it still the final word