RSJ lateral support and other questions

[iandandav]

Ive spent some time learning about the formula and calculations required for fitting a UB to partially replace a supporting wall. I have done the brain work and calculated what I'll need, beam size, block column size and materials and foundation etc.

However my research has not been able to answer some basic questions re the construction. Can anyone help

Is it acceptable for the beam to just be restrained laterally by the perendicular floor joists it will be in contact with or should the beam be attached to the joists i some way?

Should the ends of the beam be bolted in some way to padstone below it and attached in some way to the blockwork at its end face or is friction between the surfaces sufficient?


What is your padstone preference? Im thinking casting in place would be easier as the beam can be jacked up tight against the joists and the concrete poured right to the bottom of the beam.

If I use eng brick whats a good technique for getting the beam to fit tight between joists and the brick padstone. I understand packing is often used but this seems a bit of a bodge to me especially having gone to the trouble of construcing a nice brick surface for the beam to sit on
cheers
Ian

 

[themiddleagedun]

You can bolt a timber into the web of the beam and fasten joist hangers to it to hold the joists.
It's not necessry to bolt the steel to the padstone.
Too much faffing about to cast a padstone? I'd use a length of concrete lintel, prop the beam up using acrows, and pack underneath the pad' with slate, and mortar it up.

 

[tony1851]

To develop the maximum moment capacity,the top flange of the beam has to be restrained to prevent sideways buckling. Unless the beam is very slender, and/or it's a long span, this is rarely a problem with domestic loadings. As has been pointed out to you, if you want to be extra sure, you could bolt a timber into the web, and put joist hangers on to carry the floor joists, which would give some lateral restraint. However, its more likely that you will be putting the beam under the joists, so this might not apply; either way, its most unlikely to be a problem.
As the previous poster said, don't bother trying to bolt it down; its fiddly and totally unnecessary (regardless of what the building inspector might say!).
Just use a standard padstone, or cut one from a length of pcc lintel.
If done neatly, the packing is not a bodge; slate can be used, or small offcuts of thin steel plate.
Good luck.

 

[iandandav]

Yes its under the joist.
When using packing do you mean between the beam and padstone or hammered in under the padstone to push it up against the beam then push in mortar to fill any space between padstone and top of column

 

[tony1851]

Any packing goes between the underside of the steel and the top of the padstone. It does notgo under the padstone and on top of the brickwork.
This is important because it is necessary for the padstone to be evenly bedded on to the brickwork via the mortar bed. If you pack under the padstone, and then try and push mortar into the remaining voids, the mortar will shrink very slightly (which is normal.) It will then leave the padstone only supported by the packing,which will increase the localized stresses on the brickwork immediately underneath, and which defeats the object of a having a padstone in the first place.
First rule of engineering: always pack under the steel!

 

[iandandav]

Thanks Tony and TMAD. I think I have everything to go ahead now. Just need the cash to start. Its irritatring that the Buiding Control costs so much, probably as much as the job will cost me. And all just to just stroll around tick a few boxes. Nice little monopoly these people have.