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lateral stability of building
folks,
i have a lateral stability problem in an existing building that i would like a second opinion on if anybody can help.
the building is approx 25m long (west to east) x 5.5m wide (south to north). there are 2 gable walls located at each end which provide my lateral stability in the south-north direction.
normally i would assume that the timber floor acts as a horizontal deep beam and trasfers any lateral load to these gable walls.
on one floor level, the architect wants to have a double height room for a length of approx 5m at the west end only. this would leave me with a 5m x 5m ope at this end. obviously, this presents me with a problem because my horizontal deep beam is no longer fixed to the west gable wall.
i cannot place another wall or a wind portal at the edge of the floor because it is an existing building and there is separate tenancy in the basement.
i'm proposing to construct a stiff box of beams around the opening. 1 of the beams will be fixed to the floor (the east side of the opening) and the other 3 beams will be fixed to the 3 existing adjacent walls (ie the west, south and north faces of the opening).
the floor structure could now act as a deep beam spanning between the east gable wall and the horizontal stiff box of beams. the stiff box of beams could possibly be designed as a horizontal wind portal with the feet fixed to the beam that is fixed to the west gable wall.
this would provide the necessary mechanism for the wind load in the floor to get transferred back to the gable wall.
would anyone agree?
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if i get what your saying your going to build essentially a horizontal drag moment frame that the floor diaphragm will attach to. sounds like it could work. the horizontal moment frame would induce loads into the 2 east-west long walls.
a wood diaphragm is also usually considered to be a flexible diaphragm. so you could also use the long walls to resist the wind loads via torsion. if your like me though you wouldn't want to rely upon this.
if the exterior walls are block wall you could also place some angles in the corners to make sure that some of the wind hitting the corners would go right into the shear walls. this would take some of the load off of your diaphragm. you might also want place a diagonal
thanks southard2.
i especially like the final option. the only problem is that i work with the guy so it might not be appreciated!
thanks for you views. |
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