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RE: wind uplift + lateral loads

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Andrew,

 

Sounds logical to me.  I always design my uplift connectors for C&C wind pressures and we use MWFRS loads for the diaphragm.  I do include floor and roof dead loads though.  If you don’t have the floors you are most likely not going to have exterior sheathing nor the roof.  It’s my opinion that stability during construction is the contractor’s responsibility.

 

CMU construction in high wind is too easy.  You need to keep challenging yourself.  130 mph with tall studs, big windows, big balconies and overhangs is always fun.

 

 

 

Brian

 

 

 


From: Andrew Kester, P.E. [mailto:akester(--nospam--at)cfl.rr.com]
Sent: Wednesday, October 24, 2007 11:17 AM
To: seaint(--nospam--at)seaint.org
Subject: wind uplift + lateral loads

 

I would have never thought that some codes would not require you to consider simultaneously both uplift and lateral forces due to wind. We always do this down here in wind country as this is our only lateral or uplift force (no seismic).

 

We just wrapped up a two-story apartment, all wood framed, V=100mph.

-The individual truss connections are designed for uplift (using components and cladding) and for shear (MWFRS).

-Shear at each wall from the roof diaph. is determined using MWFRS

-These were bearing walls supporting wood floor joists at the 2nd floor. We used almost no dead load from the floor, as what if the hurricane hits while these are being constructed or they are built but not yet occupied? A slightly larger strap or uplift connection does not cost much compared to repairing the damage after the fact, even if we designed to the letter of the code I think lawyers could find fault....

-So we calculated overturning and uplift for each shear panel at the second story and the first story, and designed the outer chords/jambs for this C/T force and sized the straps and uplift connections for this combined affect. We also include additional uplift point loads at the jambs from the headers over windows and doors. These OT and uplift forces were taken all the way down to the foundation, and accumulated from the 2nd to the 1st story....

 

I always assumed this is what everyone else is doing but any feedback is appreciated. Also why I hate two-story + wood frame in Florida and normally turn down that type of work. CMU is so much easier in these regards and gives you lots of added dead load.

 

Andrew Kester, PE
Principal/Project Manager
ADK Structural Engineering, PLLC
1510 E. Colonial Drive, Suite 301


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