CATHEDRAL CEILING HIGH WIND STRUCTURAL DESIGN 1

[KPKKMP]

I'm designing a cathedral ceiling and I am trying to determine how the wind, live and dead loads react on the I joists which are at a 10/12 or 40° pitch. The I-joist horizontal span is 15 feet. The roof is 35 feet long. Do you take the components of the forces which act perpendicular to the I-joist then treat it as a simply supported beam with a uniform load, or take all loads as if they were perpendicular to the I-joist? Also the cathedral roof has two gable roofs which intersect it and form valleys so the wind does not push on the full area of the roof. If you are familiar with wood structures subject to high wind loads, the ASCE:7-02 or any of the high wind design codes I really need your help. if you need more information I can supply you with a 3-d model or cad drawing. Thanks!

KPKKPM

 

[boo1]

look at link "EDUCATION FOR ENGINEERS ON FUNDAMENTAL ELEMENTS OF HIGH WIND DESIGN AND THE WINDSTORM PROCESS" avalable free at:

http://www.tdi.state.tx.us/company/wind/dwnloads.html#ircpres

It covers wind effects and damages and the wind load provisions of ASCE 7-02. Learn current approaches for assessing wind loads and examining building performance in severe storms. It is also beneficial to individuals involved in the interpretation of wind load standards and codes. I found a few minor errors, but the guide is very informative.

 

[bltseattle]

Aren't cathedrals major structures used by the public? My perspective as a civil eng working with a lot of structural engineers, if I was designing a cathedral ceiling I would not be comfortable teaching myself the details of wind resistant design from a book or free web download, seems like some more experienced consultants are needed. Is the engineer of record practicing within his/her expertise here? Maybe you should consider some outside help.

 

[boo1]

Most commercial structures require PE stamps on the drawings. Hope you become more proficent with wood design before starting a structure design......

Here is some additional info for your learning quest.
Span calculator for joists and rafters from the American Wood Council.

http://www.awc.org/calculators/span/calc/timbercalcstyle.asp

The WWPA Lumber Design Suite is the newest design tool available to assist engineers, architects and designers in properly specifying and using Western lumber products.

The Design Suite, working in concert with Microsoft's® Excel program, provides calculations for Western lumber in beams, joists, posts, studs and single shear connections.

Online Free Download for Hurricane Resistant Construction SSDT-1099 at:

http://www.iccsafe.org/cs/standards/is-hrc/SSTD10/index.html

Links:

http://www.wwpa.org/techguide/suite.htm

http://www.southernpine.com/tables/index.htm

http://web.usna.navy.mil/~greg/en442/files/NDS Tables.xls

 

[cvg]

When I read this first, I assumed a cathedral ceiling in a residential building, not a church. The dimensions given - 15' x 35' don't seem to match up with a large structure...

 

[wirelesstom]

I have a 10'x18.5' floating slab foundation w/minimal loading (12,600 lbs of equipment in various cabinets). The slab is 6" thick w/#4 placed both ways at 12" O.C.. The slab is placed on compacted crushed stone.

The loading equates to 185-lbs/SF and the soil pressure is approx 1000lbs/SF. Should I worry about placing footings too or is the floating slab sufficeint?

The grade is level and not sloped. I am in the Northeast (NJ) however....

 

[boo1]

When posting recommend starting a new thread.

Have you considered frost heave and the building loading?.

 

[cvg]

wirelesstom

you should post this in the geotechnical engineering - foundation engineering forum for a better response