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Re: Joists & Adding Roof Mechanical Unit

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Are there "C" clamp type bolts that would be reliable?  Drilling holes in
the top chord of the truss would remove a lot of steel in the compression
chord.

Rich

On Sat, 30 Oct 2004 09:32:40 -0400 "Gary Hodgson & Associates"
<ghodgson(--nospam--at)vaxxine.com> writes:
> Just bolt the new pipe stanchion in place with end plates already
> welded to it.  Use 4 bolts so it is clamped in place--
> no welding.
> Gary
> 
> On 29 Oct 2004 at 12:39, richard lewis wrote:
> 
> > This sounds like it might be a feasible alternative.  So if I
> > understand this, the roof would be opened at the locations of the 
> pipe
> > post.  The pipe post base would be welded to the joist from the 
> top. 
> > Then the roof is closed again.  I can then sit a "curb" on top of 
> the
> > posts.  This would minimize disruption of the office space below, 
> but
> > I'm sure there still would be some welding sparks dropping.  At 
> least
> > the equipment is on the roof.
> > 
> > Did I understand you correctly here?
> > 
> > Thanks.
> > 
> > Rich
> > 
> > On Fri, 29 Oct 2004 13:31:19 -0400 "Jordan Truesdell, PE"
> > <seaint(--nospam--at)truesdellengineering.com> writes:
> > > Disclaimer: I'm used to using pipe columns and pitch pockets 
> for
> > > rooftop curbs.  Can you afford a three-tier curb system - two 
> rails
> > > over the panel points, perpendicular rails on top of that to 
> support
> > > the curb rails at the proper spacing?  It's more steel tonnage, 
> but
> > > it will get you to the 
> > > 
> > > bearing points of the trusses without having mess around in the
> > > ceiling.
> > > 
> > > At 10:49 AM 10/29/2004 -0500, you wrote:
> > > >I have an existing roof structure where the owner wants to add 
> a 
> > > rooftop
> > > >mechanical unit.  The unit weighs about 3,000 lbs.  The 
> existing 
> > > roof
> > > >joists are 24H9.  I checked the roof joists and supporting 
> girders 
> > > and
> > > >they are fine to support the additional load.
> > > >
> > > >I have a detailing question.  I know this has been done many 
> times 
> > > so I
> > > >am hoping someone will share their experience with me.  I plan 
> to 
> > > ask
> > > >that the unit be placed on a continuous curb that runs 
> > > perpendicular to
> > > >the roof joists.  My question has to do with the curb bearing 
> on 
> > > the roof
> > > >joist.  First, I assume the curb will bear directly on the 
> deck.  
> > > No roof
> > > >penetrations are required.  The roof deck is corrugated decking 
> as 
> > > the
> > > >joists are about 2 feet on center.  The curb will run parallel 
> to 
> > > the
> > > >deck flutes.  It is typical to just run a wood plate on top of 
> the 
> > > deck
> > > >to support the curb?  The curb will be a structural curb that 
> > > spans
> > > >between joists.  Next, in new construction when the 
> concentrated 
> > > load is
> > > >put on a joist top chord at a place other than a panel point an 
> 
> > > angle is
> > > >welded from the top chord down to the bottom panel point.  The 
> 
> > > space
> > > >below is occupied by office space and to weld a few angle 
> struts 
> > > would be
> > > >very difficult on innocent tenants.  Is there another detail 
> that 
> > > might
> > > >not involve filed welding?  Would I be able to skip the angle 
> strut
> > > >
> > > if
> > > e maximum possible point load from the curb were under 1,000 
> lbs?
> > > >
> > > >
> > > >Thanks for your help.
> > > >
> > > >Rich
> > > >
> > > 
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