Wind deflections at an expansion joint
Wind deflections at an expansion joint
(OP)
Another recent post on building expansion joints got me to thinking about this question - wondering what you all typically do or what you all think is code-correct:
One building with an expansion joint down the middle. The building might be different construction on one side relative to the other. For seismic deflections I have always calculated the amplified seismic deflections, added them up and used that value to determine the necessary joint width. In other words, in a seismic event the two building parts might begin oscillating in opposing directions - thus the joint stand-off is the sum of the seismic deflections.
With wind, for most buildings, I'm not sure I can see the buildings oscillating in opposite ways like in a seismic event. And I don't recall ever seeing anything like that requirement in the code relative to wind.
So for wind, do we assume that the required wind-based joint width might be the difference between the windward and leeward deflections (assuming no seismic)?
Or do we add the windward and leeward deflections assuming oscillation in the building?
One building with an expansion joint down the middle. The building might be different construction on one side relative to the other. For seismic deflections I have always calculated the amplified seismic deflections, added them up and used that value to determine the necessary joint width. In other words, in a seismic event the two building parts might begin oscillating in opposing directions - thus the joint stand-off is the sum of the seismic deflections.
With wind, for most buildings, I'm not sure I can see the buildings oscillating in opposite ways like in a seismic event. And I don't recall ever seeing anything like that requirement in the code relative to wind.
So for wind, do we assume that the required wind-based joint width might be the difference between the windward and leeward deflections (assuming no seismic)?
Or do we add the windward and leeward deflections assuming oscillation in the building?






RE: Wind deflections at an expansion joint
Normally, we are only concerned about oscillation of pieces and parts, not the whole building.
Ron
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
Ron
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
I guess its the idea that seismic effects tend to be multi-directional where wind is directional.
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
RE: Wind deflections at an expansion joint
Equal stiffness then maybe, but unless the buildings are identical, and built at the same time, I would say no and be conservative here.
Even with identical stiffnesses, with the windward and leeward forces being different, and timed differently due to the length of the buildings, you can get different responses, especially due to vortex shedding at the trailing edges.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask
RE: Wind deflections at an expansion joint
1. Smaller Separations or property line setbacks shall be permitted when justified by rational analysis.
2. Buildings and structures assigned to Seismic Design Category A, B, and C
I assume that the second was added so that large separations joints we not required in areas not prone to seismic activity.