Curtain Wall Deflection 2

[jopalu]

What horizontal, deflection criteria is recommended for exterior, glass, curtain walls to resist lateral wind forces? L/600? 480? 360?

On a slight tangent, what would you recommend for the following: (All due to lateral wind forces)

-Exterior structural concrete masonry also supporting gravity loads.

-Exterior concrete or brick masonry veneer.

 

[apetr26542]

Usually L/600 is reserved for masonry or veneer, curtain wall, L/360 should be adequate, however they might have criterion to follow.

 

[par060]

almost all of the aluminum curtain walls that I have designed deflection has been specified to be L/175 or 3/4" whichever is less

 

[miecz]

AISC's Steel Design Guide #3, "Serviceability Design Considerations", has L/240 listed as a Deflection Limit for wind forces in Table 1 for Exterior Walls with brittle finishes.

 

[UcfSE]

I design my curtain walls for L/360 generally unless they support brick veneer which gets a deflection criterion of L/600.

 

[quest4more]

What exactly is "Empirical Design of masonry" as per MBC 2003? If you use the NCMA software for a masonry load bearign wall design, would you consider it as a special design or an empirical design?

 

[ntpe]

For glass and al. curtain wall, currently, the most often used deflection criteria is l/175 w/ 3/4" max for spans less than 13'-6" and l/340+1/4" for spans greater than 13'-6". The old l/175 , 3/4" max was an old window criteria intended for use w/ single lites. It is too conservative for modern curtian wall design, especially when coupled with C&C wind pressures.

 

[haynewp]

For out of plane, I would use L/180 or so for curtain wall (more strict depending on the finish), l/300 or so for cmu and brick. I think a lot of people use different amounts. I usually check total deflection as well as the ratio.

You could multiply the wind load by 0.7 in IBC 2000 for checking deflections under C&C , I haven't checked if you still can in 2003.