Help with structural steel calculations please

[andyborris]

Mainly because I have no idea how to do this!

It's for a large steel platform I'd like to build and I need to calculate the steel sizes.

I won't waste bandwidth detailing the project here, but if you're an engineer/architect and can help...........please message me.

Or if you know someone who can design this for not much money, please let me know.

Thanks

Andy

[dodgerover]

I tried to be tight and went with a firm who you can send all your details to online - they were £50 or £60 per opening and came up with all the calc's to make building control happy. However it was difficult to explain exactly what I needed to do as I was working without plans, and in the end the steel was well over spec'd. and basically awkward to put in, in hind sight it would have been better to have 2 smaller steels bolted together with spacers at 600 centres rather than one big one with a plate welded on, if I had had someone on sight they may have spotted that.
There are also programs I found online that will calculate deflections etc but I wasn't confident enough about using them to follow it through.
Does whoever is supplying your steel have anybody they can recommend?

[whippet]

as a rule of thumb, its a about an 25mm off steel per 300mm of span, for structural steel, on top of that there is different thicknesses of steel, i/e web and flange size measured in kg/m, i would always go for the biggest kg/m, steel is measured in mm so an opening of 3075mm will need a 254mm high, width is 102mm or 146mm, then there's the kg/m size that starts at 22kg 25kg 28kg for the 102mm, then 31kg 37kg 43kg for the 146mm, its all dependent on point loading on the steel, i would personally find a friendly structural engineer draw up some plans of size and ask him to do some calcs,

[andyborris]

Thanks.

I've also posted details on one of those "quote a job" sites.

My problem is that I've absolutely no idea of the size of steel I need, so haven't even asked for prices yet and it's a 12m by 6m platform I need the steel for!

[composimmonite]

Might be worth asking on this forum -
www.mig-welding.co.uk/forum/index.php

Paul H

[dodgerover]

Oct 12, 2013 22:10:45 GMT andyborris said:

Thanks.

I've also posted details on one of those "quote a job" sites.

My problem is that I've absolutely no idea of the size of steel I need, so haven't even asked for prices yet and it's a 12m by 6m platform I need the steel for!

I hope thats not a 12m span? Those size steels involve serious muscle to move on the ground let alone up in the air, weight is going to be a serious consideration for what it will be bearing on. The last one I was involved with had to go in as a letter box arrangement i.e 2 steel support columns bearing down onto another steel in the ground to spread the load.....

I'm intregeed can't spell it nosey what do you need it for?

[andyborris]

It's for a raft to support a house.

The frame will (hopefully!) sit on pontoons and have a steel framed house.



Like this.

[dodgerover]

Wow, I would imagine the structural requirements etc for that would be quite different to in a house? Nice project though

[composimmonite]

Unless it's on a private lake won't it also have to conform to some sort of Waterways Authority regulations / inspection ?
Have you thought about making in the same ways as HGV trailers albeit twice as wide. They aren't rigid but allow some movement thus lighter than making something solid. The actual house aspect would then need a "subframe" that could be mounted on isolating blocks to cope with any movement. Unless you intend river or estuary usage I suspect any such movement would be very slight

Paul H

[andyborris]

Luckily, because it's not a powered craft, there are no rules or regulations!

However, because I won't own the mooring, the Marina might reject something that's too outlandish or dangerous.

My original plan involved welding 3 shipping containers together! I also thought of buying 2 HGV trailers to use as a platform.

The moorings are tidal, so the houseboat will sit on an uneven river bed for quite a few hours.

I've asked for quotes to build a platform from shipbuilders and they've all come up with huge girder platforms and a price to match. I think they're doing it via "rule of thumb", i.e. "it needs to be this strong, so we'll make 3 times that and there won't be a problem".

Just leaves the problem of finding the money to pay for it!

I'm now leaning towards making it in wood......wouldn't trust my welding skills, but gluing and screwing, I can do!

The wood is pretty cheap and if doesn't work, I'll have plenty of fuel for the log burner on the new steel platform!

[composimmonite]

With so many manufacturing businesses going bust what about trawling demolition companies to see if any are dismantling a factory or similar that has steel structures you could salvage. Something like a raised platform that is made from girders ?

Paul H

[colnerov]

Hi, having watched the demolition of an industrial type building over the last few weeks, this is not a viable source of steel because they just cut all the steel into up to 6' lengths by machines.

The problem with this project is not the support of the weight over the distance, because the water does that. But the frame needs to resist twisting both on the water and on the river bed. Having googled around over this I am reminded of the adage 'boats are just a hole in the water into which you pour money'

Colin

[composimmonite]

Oct 17, 2013 19:17:27 GMT colnerov said:

Hi, having watched the demolition of an industrial type building over the last few weeks, this is not a viable source of steel because they just cut all the steel into up to 6' lengths by machines.


Colin

I didn't mean the actual building structure but internal framework for machinery etc. Many of the factories I worked in when young had such raised platforms before the current type of mezzanine floors became popular. If they will get more from a customer for selling a platform complete rather than spending hours cutting it up, only to weigh in as scrap, you might find a smaller demolition company might be willing to help.


Paul h

[andyborris]

Paul

That's a really good idea, but I think, like the 2 HGV (no mot) trailer idea, transport costs will kill it!

Off to see an architect tomorrow, see if he can help and at what cost.