Lateral Stability
Lateral Stability
(OP)
Hi everyone.
I have a query about simple lateral stability of buildings. If you take a simple cube and apply lateral forces to it (say east to west), I normally assume the roof and any floors act as deep horizontal beams and transmit all the forces back to supporting shaer walls (north and south).
But, what happens when one of the supporting shear walls (say south) is completely missing. Say for example an aircraft hangar with a completely open entrance on one side or a steel frame structure with a full wall of glazing on one side (again the south wall)? Is it safe to assume that the twisting will be taken by the east and west walls? The structure would then be working like a 3 sided box.
What have other engineers assumed?
I have a query about simple lateral stability of buildings. If you take a simple cube and apply lateral forces to it (say east to west), I normally assume the roof and any floors act as deep horizontal beams and transmit all the forces back to supporting shaer walls (north and south).
But, what happens when one of the supporting shear walls (say south) is completely missing. Say for example an aircraft hangar with a completely open entrance on one side or a steel frame structure with a full wall of glazing on one side (again the south wall)? Is it safe to assume that the twisting will be taken by the east and west walls? The structure would then be working like a 3 sided box.
What have other engineers assumed?






RE: Lateral Stability
in your case there are several ways to satisfy this:
1. if the roof has shear-stiffness, then it distributes
the forces to the 3 remaining wall.
2. if the roof has not enough shear-stiffness (as usual in steel-structures) you may substitute your eastern wall by
a moment-frame or by columns with fixed bases
3. if the roof has a fair amount of shear-stiffness, you may consider a mixed system, maybe not the best choice..
RE: Lateral Stability
The shear in the south wall will cause the torsion you are talking about which will be resisted by all three walls, not just the east and west walls.
This will act as a three sided torsion box, as you have stated. I think you will actually find that the direct shear in the south wall will be counteracted by the torsional shear and you will get a smaller net shear in the south wall than from the direct shear alone.
RE: Lateral Stability
the forces to the 3 remaining wall."
I assume you mean a concrete roof which would be quiet stiff. What about a timber roof with say a plywood membrane fixed to the top or bottom of the rafters? In the absense of structural calculations and using experienced engineering judgement, would this be a possible solution that you have undertaken in the past?
RE: Lateral Stability
thread726-208022: Braced Steel Commercial Building
RE: Lateral Stability
of an timber roof. it may be not the best solution, considering the in plane deflections.
i sure did it in steel structures with braced roof planes.
to better understanding, do a sketch
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Incorporating the columns into portal frames also has the added benefit of reducing the size of the roof beams required.
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A friend of mine used to work for them in their sydney office.
RE: Lateral Stability
RE: Lateral Stability
Thanks guys