huangyhg

can support be moved or removed
i have a 8 x 5.5" i beam spanning 33 ft the main floor of the house. the house is two story frame construction with basement. the i beam has two supports which are steel pipe, 4" diam, wall thickness unknown. these supports rest on 6 * 3" steel plates and are adjustable in height. i would like to open up the basement area and to do this i would like to either remove one of the supports or move it 4ft twoards the centre of the span. at present the two supports are equi-spaced, ie 11 ft.
are these supports really structural or were they just left during construction? can on be removed? can one be moved, if so how?
more info or pictures can be provided.
thanks in adanvce
from your description there are acutally four supports; two pipes and two at each end of the i-beam. the two end supports are likely beam pockets in the concrete foundation wall.
these supports are there for a reason and should remain pending an engineering modification and code compliance review.
normally these pipes are placed in concrete. it appears that yours wasn't.
there are several options open to moving them around and making modifications. and this assumes the beam is continuous across each support. one would be to place a temporary support not far from the support that you wish to move. place another support away from the original support and temporary support. move the original support. provided the new distance between the new supports is no less than the original distance you may remove the temporary support.
you appear to have a w shape beam. since i am in canada my steel book is in metric but from an old imperial volume it would appear that you have either a w8x20 or a w8x17. the w8x20 would be 5.27鈥?wide at the flange and the w8x17 would be 5.25鈥? the designator is first the shape (w) the height in inches (8) and finally the weight in pounds per lineal foot. (20 or 17).
to determine the allowable span we would need to know the supported joist length on the beam.
you really need a structural engineer to come out and look at this before you remove any supports. changing supports is not something to be done lightly and if done wrong can have serious consequences.
there could be a splice in the beam over an existing support, which would require special connections for the support to be removed. the new supports will also require new foundations and other measures to carry the load to the underlying soil.
in a longer beam, especially a steel one, the deflection usually is the deciding factor. a long beam will also be more 鈥渟pringy鈥?than a shorter beam.
once any building has been occupied for any length of time the structure experiences some settlement and deflection, which will be changed by removing a beam. this may lead to cracking of drywall as the building settles into its new load regime.
get a local structural engineer to take a look at this. you may be able to trade some computer consulting for some structural consulting and thus keep costs down.
rick kitson mba p.eng
construction project management
from conception to completion
you are correct the i-beam (steel) is close to w8*20 (not sure exactly i only found specs for 17 & 21 and it is inbetween those). it is contiguous and supported at four points, ends and two columns. columns are (
don't forget that if you take away column supports (assuming that your beam can span the longer distances) you may then overload the existing foundation at the remaining column supports, resulting in settlement and all sorts of problems.
most likely, these existing foundations (be it a footing or pile) were only sized for the loads that were applied by the columns in the original support configuration.
i agree, you should hire a structural engineer to check it for you...
another consideration is that you are going to get deflection in a location where there previously was none, and it is happening to finish materials that will feel the entire effect rather than a partial or progressive deflection during the natral course of construction. expect distress.
it's just this fact that i never do "pool table in the basement" column removal jobs in residences.
dyno68,
anything is possible so long as you have the money to do it. so, this project will cost you more than you thought if you want to do it right.
if you move the column to a new location, there is no guarantee that the slab is thickened here so that the new column won't punch through. so, plan on adding the cost of a new footing to your project.
one of the above messages talks about increased deflection in the longer span you made. you can reinforce the web of the steel beam with steel plates, but again add that work to your cost and also the cost of repairing cracks that may occur above.
also, add the cost of a structural engineer to the project. i investigate failures like this all the time where contractors and homeowners proceed with professional direction.

...oops, meant to say "without" professional direction.
you won't get much reduction in deflection with web reinforcement - you need to substantially increase the beams inertia, but better yet, call a str. eng.!
tg

__________________
借用达朗贝尔的名言：前进吧，你会得到信心!
[url="http://www.dimcax.com"]几何尺寸与公差标准[/url]