We are designing a small two story office building that has a hipped roof and has a "platform" that is approximately 24'x51' and the building is 65'x92'. I am having an issue with trying to figure out how to continue the roof diaphragm at this interruption. Any ideas would be greatly appreciated.
Tek-Tips is the largest IT community on the Internet today!
Members share and learn making Tek-Tips Forums the best source of peer-reviewed technical information on the Internet!
-
Congratulations MintJulep on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!
RTU platform for a wood trussed structure 1
- Thread starter cmbyrd77
- Start date
- Thread starter
- #3
woodman88
Structural
- Oct 23, 2009
- 1,020
You sheath the vertical section of the truss. Place blocking (between the trusses) at the top of the vertical to nail the pitch and vertical sheathing to. Place two blocks (between the trusses) nailed together at the bottom of the vertical section and nail the vertical sheathing to one and the flat sheathing to the other. At the corners of the flat sheathing you may need to provide metal strapping for transfer of loads.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
Cmbyrd:
I’d be tempted to use parallel chord wood (steel) trusses, with bot. chord just above the suspended clg., and top chord at whatever elev. calced. depth required, defining the floor of the platform. Sheath this top chord out to the exterior walls for your primary diaphragm. The sloped part of the roof would just be mono trusses which included most of the framing for the eave/soffit overhangs. The mono trusses sit on the primary deck, either matching some lower trusses or crossing others. The bot. of the steel beams would be about at the same elev. as the bot. chord of the wood trusses. Then the wood trusses would be top bearing on the steel beams, and tied together across the beams. Then you do something like Woodman88 suggested to tie the roof diaphragm and the main diaphragm together by sheathing the vert. walls around the platform.
I’d be tempted to use parallel chord wood (steel) trusses, with bot. chord just above the suspended clg., and top chord at whatever elev. calced. depth required, defining the floor of the platform. Sheath this top chord out to the exterior walls for your primary diaphragm. The sloped part of the roof would just be mono trusses which included most of the framing for the eave/soffit overhangs. The mono trusses sit on the primary deck, either matching some lower trusses or crossing others. The bot. of the steel beams would be about at the same elev. as the bot. chord of the wood trusses. Then the wood trusses would be top bearing on the steel beams, and tied together across the beams. Then you do something like Woodman88 suggested to tie the roof diaphragm and the main diaphragm together by sheathing the vert. walls around the platform.
-
1
- #6
msquared48
Structural
AAAARRRRRRGGGGGGHHHHHHH!!!!!!!
I hate rooftop mechanil platforms. They are real snow drift traps and very leak prone. Put the equipment on the ground in a separate screened enclosure!
Mike McCann
MMC Engineering
I hate rooftop mechanil platforms. They are real snow drift traps and very leak prone. Put the equipment on the ground in a separate screened enclosure!
Mike McCann
MMC Engineering
Agree with Mike too. Also what is the rainfall load on this? Good discussion in itself. -Primary drainage system is blocked now, remember... See the truss CAD jocky stick that in their little programs without a loading diagram from the engineer!
I digress. Back to OP though: I like both woodman and dhengr ideas where you some from of drag strut or permanent bracing/horizontal trusswork which will transfer the diaphragm forces. Careful w/ dhengr method so you don't create cavities which need sprinklers in them if I am understanding him correctly (not sure I did all the way).
______________
MAP
I digress. Back to OP though: I like both woodman and dhengr ideas where you some from of drag strut or permanent bracing/horizontal trusswork which will transfer the diaphragm forces. Careful w/ dhengr method so you don't create cavities which need sprinklers in them if I am understanding him correctly (not sure I did all the way).
______________
MAP
msquared48
Structural
Not to belabor the point, but to belabor the point, with a rooftop enclosure, it is absolutely impossible to avoid induced vibration and noise from entering the structure from the machinery. Don't let isolation fool you. It may reduce it, but will not eliminate it.
I pushed to have the AC/Heating units mounted on the ground at our church, but they were deadset on a roofmount condition. Now, whenever the units engage, I can hear and feel them. Wonderful, just wonderful.
Mike McCann
MMC Engineering
I pushed to have the AC/Heating units mounted on the ground at our church, but they were deadset on a roofmount condition. Now, whenever the units engage, I can hear and feel them. Wonderful, just wonderful.
Mike McCann
MMC Engineering
- Status
Similar threads
- Locked
- Question
- Question
- Solved