steel "H" beam Girder

[hounddog91]

I am designing my house and i am using a design from Toll Brothers this is the house i am re-making same basic shape the room sizes are different but the same basic shape http://www.tollbrothers.com/DYOH.swf?plan=chamberlain_833_.

my question is if i am using a W 12 x 26 lb (12.22" x ..230" web x 6.49") "H" beam (well 2 of them spaced 18 feet from both the front and back walls the 2 longest walls) what is the maximum allowable spacing for the lally columns i have been reading the IRC book and i cant find anyhing in there for lally columns.

more information:
from the back wall to the front wall i have 42' and from the right wall to the left wall i have 64'.
i am going to be using Georgia Pacific GPI 90 Floor joist that are 14" Tall spaced 12" OC.

can you suggest any place to buy the girder cause i cant find any place online that give a price for a 64' long column all places i have looked only have up to 25'

[Don_P]

The spacing of the support columns depends on the loads on the beam from above. I buy steel from the local welding shop, they arrange to install per the engineers notes. Which gets around to, that plan needs an engineer.

This calc might help with a little of that;
http://theownerbuiltcabin.com/calculators/TT/steelbeamclc.htm

[MushCreek]

When you calculate the loads, make sure the columns you buy are rated for enough capacity. We have a big LVL running the length of our house, and I found that the cheap adjustable lally columns that were available in big box stores had nowhere near enough capacity. For now, I have PT 6X6's. I also found that some of the post bases for lumber columns lack sufficient capacity as well. Do your homework- the loads are surprisingly large when you're holding up a main floor. My columns are technically holding up almost 11,000 lbs. each.

[UK4X4]

here's 3 I beams I have on my UK house- one original where a previous owner had removed the houses central chimeny breast.

and then I took out the hall way wall as well.

I went to my local structrual steel shop- described what i was supporting - in this case basicly the whole of my upper floor, they sized the Ibeam - welded on the ears as the original one was in two pieces resting on the hall wall.

its held up by 1 off 4" X1/4" steel post.

The post in the UK is now illegal- we have to use I beam posts as well so that rust can be assesed- as a closed tube means it can be rusting from the inside out and not be seen

Under the steel post is the original wall that supported the upstairs, and we added 4 blocks both sides of the original wall  and back filled above with rebar and concrete making a 4ft square pad to support the weight

its not only the posts you have to concider its whats under them too !

[Don_P]

The post in the UK is now illegal- we have to use I beam posts as well so that rust can be assesed- as a closed tube means it can be rusting from the inside out and not be seen

Interesting, that is a valid point but we sure use a lot of closed shapes for their structural efficiency. To give an example look at the section properties for 2 comparable steel shapes. A W4x13 I beam has 1/4" thick web and 3/8" flanges and weighs 13 lbs per foot, so there's the quantity of steel used. It has a moment of inertia of 11.3"⁴ normal to the beam and 3.86"⁴ in the yy direction. Not so good in that direction. Compared to the square closed shape of a 1/4" wall 4x4 tube at 12.21 lbs/foot which has an I of 8.22 in either direction. It would take a much heavier open section to do the same work as the closed shape. Not that one or the other is better just an opportunity to ramble about geometric shapes.

[MountainDon]

Makes me wonder if there have been found cases of a hollow steel member rusting to the danger point, or if this is based on theory only.

[UK4X4]

Rusted out - not just the elf and safety people

England is a wet country

The old houses don't have a damp course

and water soaks up through the bricks - now I'm talking 100-200 year old properties

later ones have damp courses but we still get failures and people who put soil up above the seal

On two of my walls I had to drill multiple 10mm holes all along the wall and drip feed silicone oil to stop what we call rising damp.