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RE: Wind Uplift on Awning

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Sooo...am I on the right track?

V   = 85 mph

Exp = B

Kd  = 0.85 (Table 6-4)

Kz  = 0.57 (MWFRS, Exp. B, Case 2)

qh  = 0.00256(85)2(1.00)

    = 8.96 PSF

G   = 0.85

Cp  = 0.90

Cpi = 0.00 (open structure)

p   = (8.96)(0.85)(0.90)

    = 6.9 PSF

Dead Load of Fabric = 5 PSF

Net uplift = 6.9 – 0.6(5) = 3.9 PSF

 

I might have a hard time selling Exp. B, but other than that, how many errors did I make here?

 

T. William (Bill) Allen, S.E.

ALLEN DESIGNS

Consulting Structural Engineers
 
V (949) 248-8588 F(949) 209-2509

 

> -----Original Message-----

> From: Drew Morris [mailto:dmorris(--nospam--at)bbfm.com]

> Sent: Friday, May 02, 2008 4:14 PM

> To: seaint(--nospam--at)seaint.org

> Subject: Re: Wind Uplift on Awning

>

> Bill Allen wrote:

> >

> > I have a client who is creating a shade area by attaching a canvas

> > awning between two exterior trellises. The canvas panels are 22’-0” x

> > 16’-6” and there is a gap of about 1’-8” between them. There area a

> > total of three canvas panels to form a shaded area of about 22’-0” x

> > 38’-0”.

> >

> > I’m a noobie when it comes to the ASCE 7 wind load provisions and I’m

> > not really sure on what to use to calculate the wind uplift. My

> > interest is in the design of the cables and particularly the

> > attachment of the cables to the trellises. In my mind, I don’t think

> > these items are C&C, but I could be wrong.

> >

> > What should I use, Method 2, MFRS or C&C?

> >

> > From what table should I obtain the gust coefficients?

> >

> > TIA,

> >

> > T. William (Bill) Allen, S.E.

> >

> > ALLEN DESIGNS <http://www.AllenDesigns.com>

> >

> > Consulting Structural Engineers

> > V (949) 248-8588 • F(949) 209-2509

> >

> I would use MWFRS. The load on the cables is analogous to the load in a

> holdown, it is based on MWFRS, not C&C.

>

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