huangyhg

out of plane seismic forces in diaphragm or subdiaphragms
how do i figure out if a flexible metal deck can handle the compressive out of plane forces needed seismic design, parallel to the direction of the deck span.
i have a building assigned to design category c. the force is calculated from 12.11.2.1 asce 7-05. i would like to use the deck as the continuous ties parallel to the deck span. 12.11.2.2.4 does not apply, i will be using my joist chords in that direction. i am concerned that the deck may buckle under the compressive force. joists are spaced at 6.25 feet. i'm using 1.5 type b 22 ga deck.
any ideas?
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i wouldn't utilize metal deck in this manner, why not utilize the reinforced concrete topping as strut/tie?
if this is a roof deck, you should provide a structural steel
it is a roof deck, no concrete topping. it has tilt-up shear walls. i am using the edge angle for the chord members for the main diaphragm and the building is a box so no collector
the deck can take in plane shear. you need to find something else to take on tha in plane compressive force. how is the deck supported?
it is supported on joists and joist girders
this question has come up before. call the deck manufacturer and ask for research on the specific deck profile and span length you are looking at to put axial load into. you can have combined uplift/downward plus compression on the deck so it is not an easy calc. i have seen angles placed in a horizontal truss type fashion along the edges of a building where the forces were "high" to act as the subdiaphragm instead of counting on the perp. metal deck.
it will be taken to whatever supporting members or shea walls in the same direction you look at your seismic. since the deck is fastened to these members only every very short distance, then this
there is normally a 5ft or more space between the last joist and the wall, this is where the concern is usually the highest about the buckling of the deck parallel to its span happening...until the force spreads out into the rest of the diaphragm.
haynewp:
what you have suggested is very good for the 5' spacing. however, i am surprised to see it (5' spacing) is the normal practice in these days. i used to place the first joist as colose to wall as possible, 1'-2' clear from wall face.
the first joist placed at the typical joist spacing (5 to 6 ft) away from the wall is pretty standard for load bearing walls in my area.

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