|
Home > Archive > Building and Construction > May 2007 > steel span
You are viewing an archived Text-only version of the thread.
To view this thread in it's original format and/or if you want to reply to
this thread please [click here]
|
|
| dfleck1@gmail.com 2007-05-17, 1:25 pm |
| I have an 8"x5" steel I-beam in the basement spanning 30' with a
single post in the center supporting one floor and a roof. I would
like to move one post to 8' and would like to know how far in from the
other end I would have to add an additional post. I'm trying to open
up the space for a recroom.
| |
| Bob Morrison 2007-05-17, 1:25 pm |
| In a previous post dfleck1@gmail.com wrote...
> I have an 8"x5" steel I-beam in the basement spanning 30' with a
> single post in the center supporting one floor and a roof. I would
> like to move one post to 8' and would like to know how far in from the
> other end I would have to add an additional post. I'm trying to open
> up the space for a recroom.
>
Hire a local engineer to evaluate the loads and make recommendations. It
won't cost very much and you will be assured of a proper solution.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
| |
| PeterD 2007-05-17, 5:25 pm |
| On 17 May 2007 08:03:35 -0700, dfleck1@gmail.com wrote:
>I have an 8"x5" steel I-beam in the basement spanning 30' with a
>single post in the center supporting one floor and a roof. I would
>like to move one post to 8' and would like to know how far in from the
>other end I would have to add an additional post. I'm trying to open
>up the space for a recroom.
saying 5 x 8 steel I beam doesn't tell us enough to give you a
meaningful answer. The thickness of the steel in the web, and plates
is an important factor.
That said, steel is not as strong as many people think it is. Right
now you have two 15' spans if there is a single support in the middle.
Were you keep that 15' maximum span (not a good assumption, only an
engineer can pinpoint the load points), then were you to move the
support to 8 ft from the end, then then next support would need to be
at 8 + 15 ft, or 23 ft. Safer might be just to use two: one at 8 ft
from each end.
But: get an engineer (as the other poster suggested) to evaluate the
situation.
| |
|
| Frankly, I would be more concerned about what the moved posts are
sitting on.
"PeterD" <peter2@hipson.net> wrote in message
news:9hcp43tif88h4lc71tjh7hgftpqpdvdr5p@4ax.com...
> On 17 May 2007 08:03:35 -0700, dfleck1@gmail.com wrote:
>
>
>
> saying 5 x 8 steel I beam doesn't tell us enough to give you a
> meaningful answer. The thickness of the steel in the web, and
> plates
> is an important factor.
>
> That said, steel is not as strong as many people think it is.
> Right
> now you have two 15' spans if there is a single support in the
> middle.
> Were you keep that 15' maximum span (not a good assumption, only
> an
> engineer can pinpoint the load points), then were you to move
> the
> support to 8 ft from the end, then then next support would need
> to be
> at 8 + 15 ft, or 23 ft. Safer might be just to use two: one at 8
> ft
> from each end.
>
> But: get an engineer (as the other poster suggested) to evaluate
> the
> situation.
| |
| Bob Morrison 2007-05-17, 8:25 pm |
| In a previous post Glenn wrote...
> Frankly, I would be more concerned about what the moved posts are
> sitting on.
>
Exactly. Thus the reason for my recommendation to hire a local engineer
to evaluate the situation and make recommendations.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
| |
| Steve Barker 2007-05-17, 8:25 pm |
| That's a good point. Even with an engineers recommendation, there won't be
a proper pier under the new location(s)
--
Steve Barker
"Glenn" <pilcheg@kc.rr.com> wrote in message
news:464cccf2$0$27042$4c368faf@roadrunner.com...
> Frankly, I would be more concerned about what the moved posts are sitting
> on.
>
>
>
| |
| PeterD 2007-05-18, 9:25 am |
| On Thu, 17 May 2007 16:46:57 -0500, "Glenn" <pilcheg@kc.rr.com> wrote:
>Frankly, I would be more concerned about what the moved posts are
>sitting on.
>
>
Good point. Most basement slabs are a flat pour, which should be OK
here. But in reality it could be anything, couldn't it? One could do
some cores and determine the composition of the slab at each proposed
location...
| |
| Bob Morrison 2007-05-18, 1:25 pm |
| In a previous post Steve Barker wrote...
> That's a good point. Even with an engineers recommendation, there won't be
> a proper pier under the new location(s)
>
If I were the engineer I would specify that a new footing must be placed
under any new columns. It generally means cutting a hole in the floor
slab, excavating 10-12 inches deep, adding a rebar mat and pouring back
flush with the floor. A variation can include hanging the new column from
the beam before pouring concrete so that the base plate is buried in the
new pour -- no exposed anchor bolts to trip over.
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
| |
| CWatters 2007-05-18, 5:25 pm |
|
<dfleck1@gmail.com> wrote in message
news:1179414215.154847.6110@h2g2000hsg.googlegroups.com...
> I have an 8"x5" steel I-beam in the basement spanning 30' with a
> single post in the center
So the beam is actually two 15' spans.
> I would like to move one post to 8' and would like to know how far in
from the
> other end I would have to add an additional post.
If the load was uniform then you might expect the beam to be ok as long as
you don't create an unsupported section greater than 15' long.
30-8 = 22 which is greater than 15' so you do need another post say 7 or 8
ft in from the other wall. eg A spacing of 8,14,8 would seem possible.
But it's likely the load isn't uniform and there are other factors that must
be considered. You absolutly must get this designed by a professional (which
I am not).
| |
|
|
"CWatters" <colin.watters@turnersNOSPAMoak.plus.com> wrote in
message
news:464e0536$0$8750$ed2619ec@ptn-nntp-reader02.plus.net...
>
> <dfleck1@gmail.com> wrote in message
> news:1179414215.154847.6110@h2g2000hsg.googlegroups.com...
>
> So the beam is actually two 15' spans.
>
Technically, the beam span is closer to 12', time you allow for
the point of inflection past the post on either side. So it is
carrying a good load.
| |
| Dennis 2007-05-18, 5:25 pm |
| As you can see by the answers you have received, it's a costly procedure at
best. There are many structural considerations to take into account, not
just adding additional steel columns (or lallys).
Your best over all approach might be to reconsider how you could lay out the
basement with the existing column in place; perhaps over near a wall or
decorated to partially hide it.
If you still want to remove the existing column and add additional ones, you
have no choice but to hire a local licensed structural or civil engineer and
have him analyze your specific situation. (Remember, even if you sell the
home in the future, you would continue to be responsible for this basement.
Having an engineer sign off on it places the responsibility onto him as far
as the insurance and future lawsuits go.
<dfleck1@gmail.com> wrote in message
news:1179414215.154847.6110@h2g2000hsg.googlegroups.com...
>I have an 8"x5" steel I-beam in the basement spanning 30' with a
> single post in the center supporting one floor and a roof. I would
> like to move one post to 8' and would like to know how far in from the
> other end I would have to add an additional post. I'm trying to open
> up the space for a recroom.
>
| |
| Bob Morrison 2007-05-18, 8:25 pm |
| In a previous post Dennis wrote...
> As you can see by the answers you have received, it's a costly procedure at
> best. There are many structural considerations to take into account, not
> just adding additional steel columns (or lallys).
>
> Your best over all approach might be to reconsider how you could lay out the
> basement with the existing column in place; perhaps over near a wall or
> decorated to partially hide it.
>
> If you still want to remove the existing column and add additional ones, you
> have no choice but to hire a local licensed structural or civil engineer and
> have him analyze your specific situation. (Remember, even if you sell the
> home in the future, you would continue to be responsible for this basement.
> Having an engineer sign off on it places the responsibility onto him as far
> as the insurance and future lawsuits go.
>
An excellent summary of the structural issues and future liabilities.
Good show!
--
Bob Morrison, PE, SE
R L Morrison Engineering Co
Structural & Civil Engineering
Poulsbo WA
bob at rlmorrisonengr dot com
|
|
|
|
|