No Horizontal Reactions allowed
No Horizontal Reactions allowed
(OP)
Folks,
I am providing shop drawings for a lightweight fabric structural system.
What I have existing is 4 HSS columns in a 30'x30' grid pattern.
Connecting these columns are 4 HSS10x6 beams. My structure (thinking trusses, etc.)
rests on top of the beams (or it appears to based on the structural drawings).
There is a note on the structural drawings stating "no horizontal reactions to the HSS
beams from DL and LL are allowed". Seismic design category = D. I have modeled
as reactions at discrete points (zoom to see) along the beams.I would appreciate some
thoughts from the group as to how this "no horizontal reactions" could be accomplished. Thanks in advance.
I am providing shop drawings for a lightweight fabric structural system.
What I have existing is 4 HSS columns in a 30'x30' grid pattern.
Connecting these columns are 4 HSS10x6 beams. My structure (thinking trusses, etc.)
rests on top of the beams (or it appears to based on the structural drawings).
There is a note on the structural drawings stating "no horizontal reactions to the HSS
beams from DL and LL are allowed". Seismic design category = D. I have modeled
as reactions at discrete points (zoom to see) along the beams.I would appreciate some
thoughts from the group as to how this "no horizontal reactions" could be accomplished. Thanks in advance.






RE: No Horizontal Reactions allowed
BA
RE: No Horizontal Reactions allowed
If the HSS structure is rigid, you would be able to land only on the columns with pins and rollers to avoid lateral forces at the foundation. Landing on the beams would cause bending moment at the top of the column.
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin
RE: No Horizontal Reactions allowed
BA is correct. There WILL be lateral forces to the HSS sections, just not from Dead or live if detailed properly.
Mike McCann, PE, SE
RE: No Horizontal Reactions allowed
Is the particular problem that prevents the fabric structure from meeting these requirements? The screen capture looks like the supports of this structure are pinned. You may want to change all but a couple to rollers.
RE: No Horizontal Reactions allowed
RE: No Horizontal Reactions allowed
RE: No Horizontal Reactions allowed
Faith is taking the first step even when you can't see the whole staircase. -MLK
RE: No Horizontal Reactions allowed
BA
RE: No Horizontal Reactions allowed
BA, I have asked to EOR just that and am awaiting a response.
DD
RE: No Horizontal Reactions allowed
Good. How's Dylan doin'?
BA
RE: No Horizontal Reactions allowed
Dylan is about like every other teenage male knucklehead.
RE: No Horizontal Reactions allowed
Faith is taking the first step even when you can't see the whole staircase. -MLK
RE: No Horizontal Reactions allowed
Sorry to be cynical here, ... well, not really,
Mike McCann, PE, SE (WA)
RE: No Horizontal Reactions allowed
But, yes, there isn't any way horizontal forces can't occur during a lateral loading event.
Wonder what kind of weasel words we can place on our drawings.... LOL!
RE: No Horizontal Reactions allowed
RE: No Horizontal Reactions allowed
RE: No Horizontal Reactions allowed
That last would be possible if the roof had four gables, not two, or four bowstring trusses with a fabric membrane stretched over them and the ends of radial compression members stretching from corner to corner, with cables sewn into hems forming catenary edges.
... which is sort of what I thought of When I read "... lightweight fabric structural system ...", not a trussed Cape roof with a full veranda, framed in a normal way but covered with fabric skin.
A structure vaguely similar to what I've described, with fewer compression members and no arches and no planar surfaces, got a lot of publicity when installed over the inter-terminal sidewalks at Fort Lauderdale International Airport. It got less publicity when Hurricane Wilma blew away the skin. The posts, crossbeams, and cables comprising the skeleton are still there. I guess there was no money or no plan for repairs.
Mike Halloran
Pembroke Pines, FL, USA
RE: No Horizontal Reactions allowed
Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin