RTU platform for a wood trussed structure
RTU platform for a wood trussed structure
(OP)
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.






RE: RTU platform for a wood trussed structure
BA
RE: RTU platform for a wood trussed structure
RE: RTU platform for a wood trussed structure
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.
RE: RTU platform for a wood trussed structure
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.
RE: RTU platform for a wood trussed structure
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
http://mmcengineering.tripod.com
RE: RTU platform for a wood trussed structure
RE: RTU platform for a wood trussed structure
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).
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MAP
RE: RTU platform for a wood trussed structure
RE: RTU platform for a wood trussed structure
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
http://mmcengineering.tripod.com
RE: RTU platform for a wood trussed structure
BA