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_ (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'
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
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.
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 !
(https://i56.photobucket.com/albums/g165/POshaughnessy/DSC00440.jpg)
QuoteThe 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.
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.
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.