Span solution

Regarding the thread about the span itself it turns out that Georgia Pacific
and others make wood I joists capable of spanning 34' and more, with a 16"
joist 12" o.c.

http://www.gp.com/build/englum ber/technical_data.html

has data on GP products...

Matthew

In article <3898D445.38042 @bellsouth.net>, x @bellsouth.net



Thanks, look forward to seeing it.

Actually the existence of the book of tables may well answer my question,
of course.

Andy

I've done 16' spans before using microlam beams.

If memory serves the last one was a 16' span using three beams that were 9"
deep for a bridge 3 or 4 feet wide.

A building supply (a real lumber yard, not home depot) will usually have a
salesman who can help you size the beams.  There is typically a bit of lead
time involved because most yards don't stock microlam.

Just another thought...

David Boevers
Commercial Theatre Project Manager/Project Engineer
Las Vegas, NV

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I believe microlam and paralam are both brand names, and gluelam is more vague.
 I really am not versed in all the different brands.

What I did discover is that some of the laminated beams are meant for use as
cap plates for foundations and are not span rated at all.  So my one piece of
advice would be to be sure you're looking at a span rated material.  The
supplier shuold be able to provide you with the manufaturer's span tables.
These will show required depth and spacing for a given span and live load.

The cost is obviously higher than traditional lumber, and you may have to
absorb some shipping expenses, but against the labor of fabricating a truss it
doesn't look so expensive.

Like I said in my last post, I seem o remember using 1.75" wide, 9" deep
microlam on 18" centers to span 16 feet.  I doubt any TGI or TJI joist would
make the span.  But I've been wrong before - check the span tables...

David Boevers
Commercial Theatre Project Manager/Project Engineer
Las Vegas, NV

Address is filtered, remove "SPAMBLOK" to reply

Is microlam the equivalent of Gluelam/paralam or is it a more traditional
engineered lumber?  Any idea on cost?  How is it to work with?
I wonder if the mdf engineered joists would be adequate for a 16 foot span?

<20000201160012.28820.00000 @ng-fw1.aol.com>...

We use 1/4 inch lauan for hard flats, attached with #6 sheet
metal screws.  According to an article in USITT, the folks who
came up with this method attached canvas by wrapping it around
the back and using drywall screws every six inches.
  We cover the lauan with muslin.  But we're covering a set of
flats for the next show driectly with duveteyne, so I'll let
youknow if that actually works - I think the cloth will get
twisted up around the screw, myself.

We use the studs for cross-bracing, and no corner bracing is
needed.  I've been meaning to scan the photos, as someone else
requested pix a few months ago.  I'll try to dig them up.

We wear gloves during fabrication, then duct tape over any bits
that may be contacted during performance.  But all the sharp
edges are pointing towards the inside of the unit.

Well, the 1-5/8" stud is just to hold up drywall.  But they
build houses out of the stuff, so steel stud in general is up to
most tasks.

--
{:-(         Dionysian Reveler

We all agree that your theory is crazy,
but is it crazy enough?
                Niels Bohr  (1885-1962) (to Wolfgang Pauli)

In article <38962884.73EC @bellsouth.net>, x @bellsouth.net

Hm, that's an interesting idea.

How do you attach the covering of the flat and make up the corners/cross
bracing?

Also the stuff sold in the UK as metal studding has quite sharp edges as I
recall. Is the US stuff different/do you just live with it/do you have
some way around it?

I would see a problem about using it for anything that supported load in
the sense that I don't think such studding has any kind of stress rating -
or does it?

Andy

am wanting to build a bridge that has either 1 32 foot span or 2 16 foot
spans. Any ideas? Anyone tried this with a 2 x 4 truss?

In article <uw7l4.14074
$nh2.247 @cac1.rdr.news.psi.ca>,
  "Matthew R. Bates" <mat @istar.ca> wrote:
500lbs (2 actors plus 3/4 inch plywood
support.. ie the max point load
than sitting between
height

considering.. incorrectly built
think-- 2 x 12 span supported underneath with a 2
x 4 truss- so the truss would really just be
supporting the 2 x 12-

Forget the 32 foot span- think this would work
for 16 foot span?
would advise strongly advise
friendly engineer who advises us
32 foot span or 2 16 foot

Sent via Deja.com http://www.deja.com/
Before you buy.

In article <389513A6.764A7 @bellsouth.net>,



Where do you get these studs and how much are they?

Sent via Deja.com http://www.deja.com/
Before you buy.

We get ours from a building supply company - we get a discount
no that we've opened an account with them.  Home Depot carries a
limited stock of steel stud.

Don't have a price off hand (I don't order material, so I'll
have to ask) but the costs are generally 20% - 60% less than a
similar amount of wood, depending on the specific material.  

  For example, we now use 1 1/8 25 ga stud for framing flats.
We can get a bundle of ten @10' sticks for $14.  Compare to 100
feet of 1x3, then realize that there is no wastage due to knots,
warps or other imperfections.  And it doesn't weigh anything -
the whole bundle weighs less than ten pounds.

A final note - I had the gauge wrong - we'll be using either
18ga or 16 ga on our structure.  We just got the drawings in, so
we'll know more tomorrow.

--
{:-(         Dionysian Reveler

We all agree that your theory is crazy,
but is it crazy enough?
                Niels Bohr  (1885-1962) (to Wolfgang Pauli)

A sixteen foot span is quite a gap, considering most nominal dimension
lumber uses 4 to 8 foot spans...
Can you consider any of the following (this being theatre and all)
-build it out of steel and dress it to look like timber, then you could make
decorative truss out of 1/4 or ply, enourmous weight savings, and dollar
savings, you could probably recover some money from the steel
- hide a intermediate support a) through the upstage curtain (think of the
magician levitating lady gag) or through the floor, a semi hidden pipe
coming up from the trap room idea.
-can you hang the structure from the ceiling with wire rope, get some advice
from an expert, but black sheathed wire rope is very low visibility.

Remember if you build a bridge that looks nice the director is guaranteed to
put the whole cast on it.... unless its a two hander don't count on
designing it for 500 pounds....
Don't forget to prevent access during construction on stage either, people
love to come explore and if its not done, they love to fall off and through,
stairs and bridges are death traps until finished...

If your'e determined to build a timber structure, if you have time, consider
calling a local university and maybe getting the civil engineering dept to
use it as design problem....? something that happened to me in univ...

Enjoy, hope this helps
Matthew B

I would not consider building such a structure with 2x4 in any
arrangement.

We're building a 34 foot span in two sections - we're using 8"x
20 ga steel stud, assembled as i-beams, on two foot centers.
Each half will be at a slight incline, meeting in the middle
(we're waiting on drawings from the designer, but should start
on working drawings tomorrow).

The advantage to steel stud construction is that you get the
strength of steel, but do not need welding equipment or abrasive
saws.  It's also inexpensive.  And much, much lighter.

--
{:-(         Dionysian Reveler

We all agree that your theory is crazy,
but is it crazy enough?
                Niels Bohr  (1885-1962) (to Wolfgang Pauli)