enclosed structure - wind load basic question
enclosed structure - wind load basic question
(OP)
do you consider sidewall pressure for MWFRS (global design)?
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enclosed structure - wind load basic question
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enclosed structure - wind load basic questionenclosed structure - wind load basic question(OP)
do you consider sidewall pressure for MWFRS (global design)?
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RE: enclosed structure - wind load basic question
For the direction considered, I consider the front, rear and roof pressures. The side wall, for that direction, I don't, but wind up doing so when considering the opposite direction as the sidewall becomes either the front or the back.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: enclosed structure - wind load basic question
It turns into a giant jumble-#@4% mess.
Then you toss in the wind torsion cases and it gets really fun!
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
Sidewall pressure + winward pressure will cause individual footing to have bi-axial moment.
RE: enclosed structure - wind load basic question
I let RAM generate the cases and combinations. The first time I saw over 200 different combinations I knew I would never do it by hand.
Just to talk about it, though, there are only two cases where you have wind in pure "X" or "Y" directions. Every other case has some kind of quartering wind, or torsional wind case, or some other case you can't/won't do by hand. So there's always pressures on the side walls (if you want to call them that when the wind isn't really acting in the pure "X" and "Y" directions).
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
A lot of buildings out there are still designed without a 3-D model... On many low rise structures its less effort.
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
but fig 6-6 got me confuse if i should consider sidewall pressure.
i am not asking about fig 6-9 wind load cases.
RE: enclosed structure - wind load basic question
Sidewall pressure is generally irrelevant as it is less than the windward/leeward pressures, so when the wind blows from the other direction (so that the "side" walls are now the windward leeward walls), the main windward/leeward pressures will control.
RE: enclosed structure - wind load basic question
RE: enclosed structure - wind load basic question
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: enclosed structure - wind load basic question
Generally the comments above are correct - the sidewall pressures don't normally come into play. But there are certain structural systems where they do:
Say you have a one story, warehouse type of structure with wind blowing in the North-South Direction.
The sidewalls are on the west and east sides.
The structural system is steel columns and beams/joists using some type of concentric brace system, or a moment frame. Some of the side wall columns could be part of the lateral force resisting system and receive stresses from the North-South wind pressures - this due to lateral shears in the plane of the sidewalls and these would be either axial forces for a concentric brace, or bending and axial for a moment frame.
But if those same columns also supported horizontal wind girts, the columns would be recieving load from the MWFRS North-South wind pressures (windward and leeward) and ALSO the columns would be recieving bending outward due to the MWFRS sidewall pressures.
Thus, the sidewall wind pressures can come into play in a necessary, code-required design check.
This is not to be confused with C&C loading as that would be a separate check for those side wall columns, independent of the MWFRS loads brought into the columns as part of a brace.
RE: enclosed structure - wind load basic question
I have designed some new industrial facilities. I once had a FEM model with building loads and crane loads together. I figured for the hell of it I would blindly create all of he possible load combinations in a spreadsheet. It took me about two days (had plenty of time of this job and there were many buildings on one site that i figured would have similar load combos).
I literally wound up with something like 500 load combinations. I figured I'd run the models and see if most of the member designs were based on "obvious" load combos...turns out there were plenty of members designed by load combinations I never would have thought of had I not blindly made the combinations.
RE: enclosed structure - wind load basic question
JAE...hadn't thought of secodary effects, but you're right...under some systems there will be some. The OP was regarding sidewall pressure, which would be direct but incidental application....in that case I would not apply pressure to the sidewalls as a result of pressure on the primary walls.
RE: enclosed structure - wind load basic question
thanks,
RE: enclosed structure - wind load basic question
Not sure what you mean.
Am I proud that I created 500 load combos? Not at all.
That doesnt less the fact that L/C 168, 275, 289, 120, 54, 98, 65, 333 controlled the designs of certain members.
The overwhelming majority of these cases was the result of various wind + crane loadings.
RE: enclosed structure - wind load basic question
I think we are all thinking for your average box-like structure, low rise, with tilt or CMU walls, the side wall pressures usually do not come into play...
RE: enclosed structure - wind load basic question
The whole discussion above is based on the Figure 6-6 that shows sidewall pressure. Your question: "what does ASCE fig 6-6 mean?" is too general. Please be more specific.
Thanks.
RE: enclosed structure - wind load basic question
fig 6-6 shows direction of wind in horizontal but it shows there are sidewall pressure. so i am confuse why i shouldnt add sidewall pressure.
others say it will cancel out but i dont agree if you have isolated footings. isolated footings will have bi-axial moment due to sidewall pressure.
i do see in wind load guide by mehta examples that sidewall is not considered for mwfrs.
RE: enclosed structure - wind load basic question
Structural Design Engineer
New York, NY
RE: enclosed structure - wind load basic question
So if sidewall pressures will affect your structure, consider it in design. For your average box-like structure with shear walls, it will not control.