Steel building upright beams foundations

[david.cawkwell]

Hi group,

A question on erecting a steel frame barn/shed.

I've currently been laying out the base for a steel shed which is going nicely if a little slow.

My question relates to the pegs or pins for the steel uprights.

The particular building I am doing has pegs which need to be set in concrete and the upright beams bolt down onto these pegs.

My plan is to lay the base with squares left where the concrete for the upright beams will go. I then intend to bolt the pegs through a wood template held across the square in the right place while I pour the concrete into the holes for the pegs.

However I can't see quite how the concrete will be level enough (or will it?) to ensure the upright beams are perfectly vertical. Whilst my uprights are only 12ft high how do they do this for even taller buildings? Will I have to push washers or pieces of coke can underneath the base plates to get the uprights vertical?

Or is there a better way of doing this?

[keith_765]

Lay the whole floor level. then place the up right and base plate in position, drill through the anchor holes in the base plate through into the concrete and use either chemical fix or anchor expanding bolts.

[Phil L]

Close but no cigar!

Put the 'pegs' (as you call them) in as you have mentioned (and I hope your pegs are at least a foot or more in length?) Then when it comes time to erect the beams, use steel packers (shims) underneath to get the beams upright. Once everything is tickety-boo, you mix a wet slurry of neat cement and

*very* fine sand and pour this underneath the bottom plate as a grout - a lot of structural engineers insist on this even if the bottom is perfectly flat - they prefer to have a 1-2mm gap left and grouted afterwards rather than bolting straight down.

[BRG]

David,

There are various ways and I have shown one standard method for a new building at the following tinypic.com link

aware that the sketch is 'rough and ready' but it should give you an idea. Note, that using this method, you would construct the bases first and then install the concrete floor after the columns and the rest of the steelwork have been fitted.

Hope it helps

BRG

[somebody]

In message , " [e-mail]" writes

Google for "cementitious grout" or try...

Bear in mind that different grouts support different nm loadings and cater for different depths of fill.

As to your pins/pegs, accuracy is the problem there. I wouldn't try and set pegs etc into the wet concrete beforehand. Instead get the beams into position (supported) and then drill and insert threaded bar using a resin fixing. Once that is set, pour the grout and once that is set tighten the nuts down onto the plate / steel.

Hth

[Tim Lamb]

I have erected several steel frame agricultural buildings (BS5502ag) and found the above method straight forward if a little stressful.

Bases first, usually 900mm cube. The holding bolts are often supplied as an assembly with inverted cones rather than straight tubes as above. The bolt heads are retained by steel plates which create anchorage when buried in wet concrete. The cones allow considerable movement when finally positioning the steel frame.

The critical bit is having the entire site pegged out so that you can rush in and position the holding bolt assembly while the concrete lorry is washing out.

Final positioning requires a block of wood and a sizeable sledge hammer:-) Steel spacers can only lift so you need to find which post is highest for a reference. Cement slurry under when you are certain.

regards

[david.cawkwell]

Thanks to all that replied. Very useful. I am laying the floor first before the uprights as I have a forklift and having the floor there to support the forklift for lifting the uprights into place will make things much easier. Yes bolts are about 15 inches long with a curl on the end. So I think I will set the bolts then spread a sand cement or this grout mix around the bolts, shims if necessary. Then lift the uprights on with the forklift and bolt down to vertical. Hopefully all should go well.

[Tim Lamb]

In message , " [e-mail]" writes

OK but your holding bolts are not going to sit where you put them: in wet concrete. A short length of 6"x1" with the bolts fitted through should float well enough to stay put.

Are you fitting wind braces? These tend to enhance positioning errors in the uprights:-)

You haven't said but, if this is a portal frame, you may decide to pre-assemble the rafters before lifting into position. 12' eves implies a building width of 24 or 30' and at 12.5 roof pitch another 3' of height at the ridge. For final positioning it is much easier to have the rafter assembly hung on a strop or short length of chain. Will your fork lift reach say 18'?

Probably outside elf and safety but many forks can be reversed giving you an extra few feet of height:-)

regards

[david.cawkwell]

Yes still going to use wood template to hold the bolts in place while the concrete sets. I'm going to pre-assemble the rafters and lift with the forklift. It is a three stage lift so should do it. Otherwise I might need to lift another beam/something and hang the rafters from that to get the extra height. Building is 16x11metres with height of a little under 4 metres. Hopefully all should go according to plan.

[Tim Lamb]

In message , " [e-mail]" writes

I have made an*I* beam extension for my forklift.

With the forks closed either side of the web, all you need is some welded pockets to stop them spreading and a loop at the other end to secure the strop..

If you can tilt the mast, you gain a few feet more height. The extra projection is useful for carting long objects through narrow openings.

Few nice days forecast.

regards

[Micahed]

Hi all,

I hope I'm not hijacking this thread.

I am looking at building a portal steel garage under 4 metres high , about 6x8 probably about 12degrees pitch on the roof , can anyone recommend any prefabricated units ? any impressions of units on the market ? what size / depth foundations should I expect to use ?

Cheers

Micah.