What magnitude of minor lateral force on Great Room wall makes it shake
What magnitude of minor lateral force on Great Room wall makes it shake
(OP)
I was pushing laterally on a 20'Hx25'W Great Room wall the other day to show the builder how weak the wall was. With only me pushing on the wall at about 4' to 4.5' from the floor, you could easily see it moving in and out. The wall is almost all windows and doors. It was framed with 2x4 syp wall studs. The upper half is mostly windows and the lower half is windows and doors. It passed city inspection I am told but that may not be true.
There are several framing issues that created the problem, but in shoving on the wall, I told the builder I cannot push horizontally on the wall more than about 1/3 my body weight and that was minor in comparison to the wind the wall was supposed to resist (5,000 lbs or more). The builder claims people can push more than their body weight and used someone bench pressing as an example. I know the bench pressing is not applicable to this.
My question is mainly, how hard can someone push laterally from shoulder level against something when they have nothing bracing them from overturning themselves. I used 3' spread of my feet and 4' to 4.5 for the distance to my shoulder and that is where I get my 1/3 approximation. Does that sound right? (3'/2)xP = 4.25xH ---> H = .375P -----> Ballpark 1/3 your weight.
There are several framing issues that created the problem, but in shoving on the wall, I told the builder I cannot push horizontally on the wall more than about 1/3 my body weight and that was minor in comparison to the wind the wall was supposed to resist (5,000 lbs or more). The builder claims people can push more than their body weight and used someone bench pressing as an example. I know the bench pressing is not applicable to this.
My question is mainly, how hard can someone push laterally from shoulder level against something when they have nothing bracing them from overturning themselves. I used 3' spread of my feet and 4' to 4.5 for the distance to my shoulder and that is where I get my 1/3 approximation. Does that sound right? (3'/2)xP = 4.25xH ---> H = .375P -----> Ballpark 1/3 your weight.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
What might be more valuable is to put a floor weight scale against the wall and see how hard the builder can push. If it is less than 5,000 pounds and the wall moves a noticeable amount then that indicates there might just be a problem.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Fmax = W*e/h
W = weight of person
Fmax = maximum force against wall
e = horizontal distance from c.g. of W to c.g. of foot furthest from wall
h = height of horizontal force Fmax
BA
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Looks like a problem.
Get a scale and ruler on a stand, flex the wall, record load and deflection.
= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
3DDave- I asked if what I figured out sounds right.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Isn't that a question?
Maybe ask only one question if want the answer to only one question.
I told you how to exactly determine that value - you do own a bathroom scale, don't you? You have access to a wall. You could have found out in the time it took to complain about my very correct answer.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
With a coef of friction of about 0.5, I suspect the push would be about 100 lbs max. If on an angle, maybe a little more becaused of the apparent 'added' weight.
Was the wall built from any drawings? or did the contractor just 'build it'? The use of a scale would give a good approximation of the load.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I don't know too much about the residential code, but there might be some prescriptive designs in the code for which to compare your wall.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
image edited
BA
RE: What magnitude of minor lateral force on Great Room wall makes it shake
----
just call me Lo.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
dik-I think the contractor just built it. I doubt the plans were detailed.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Owner was concerned due to movement so that is why I went out. They saw it move with a moderate wind. At this stage, the builder has to get his own engineer involved since he thinks it is ok. I do not know who he will get but I am confident it will not work.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
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RE: What magnitude of minor lateral force on Great Room wall makes it shake
Shouldn't really need calculations to win this argument with the builder though... If a wall is visibly moving under moderate wind or human pushing, isn't that objectively unacceptable for conventional US construction "by inspection" ?
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
If someone short of a World's Strongest Man competitor can move the wall enough to see it, that's good enough proof for me.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
But in terms of putting a number to the force, why not put a bathroom scale between your hands and the wall? I would try to find an analog version, digital ones make you wait until it is at equilibrium sometimes..
Those of you at home today could probably give the OP the rule of thumb he is seeking (% of body weight while standing at a normal stance pushing on a wall) in a few minutes..
All of this assuming bathroom scales work vertically, but I think they should (accurately enough for this anyway).
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Static push was ~35 lbs, shoving hard was ~70 lbs. I weighed in at 155 lbs and was wearing socks
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I would think the absolute upper bound would be what the person can overhead press, not bench press. 200 lb is a lot for a recreational athlete. 300 lb is a lot for almost anybody. The world record clean and press is about 500 lb iirc. Take those times the cosine of about 45 deg.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Thanks bones206, at least that gives a starting point. 1/3 of body weight woudl be 50. You hit between 35 and 70.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Available friction underfoot would be another consideration.
W*e + Wbs*d = Fmax*h
BA
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I think you are using a scalpel where an axe would be more appropriate.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Also this whole scenario is interesting. In my opinion, if the builder finds an engineer to qualify this without changes, feel free to report them to the board.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Without e, there's minimal force against the wall, I suspect.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I doubt an engineer will sign off on this. The ball is in his court. Find one that will, let them do their calcs and submit them for review. At 10 psf wind and 500 square feet compared to maybe 100 lbs max a person can push.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
BA
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
-Dik
RE: What magnitude of minor lateral force on Great Room wall makes it shake
Rather than pushing the wall over with a purely horizontal force, one would push both horizontally and up, essentially becoming an axial member. This does two things, it eliminates the overturning problem and it also increases the friction force between your feet and the floor (by increasing normal force). This will allow you to exert much more force on the wall, which will only be limited by your strength or the frictional resistance between you and the wall or floor.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I'd guess an average man can overhead press no more than 120 lb, so that's about 85 lb maximum horizontal force.
RE: What magnitude of minor lateral force on Great Room wall makes it shake
RE: What magnitude of minor lateral force on Great Room wall makes it shake
I can't hold a lot more above my head than I can overhead press. It becomes a stability problem. LOL. I guess I'm making the leap that this is about all anybody could muster.
RE: What magnitude of minor lateral force on Great Room wall makes it shake