WINDLOAD ON OPEN ROOF FRAME - ASCE 7-05 FIGURE 6-18A

[fatihash]

My structure is roof structure which starts at 41.2m level of building and ends at 47.85 m level .
span 10.6m
width 8.1 m
height of roof structure one side 6.65m and other side 2.15m

I calculated qh as 1.47 KN/m2 , G = 0.86

1. I considered wind load as per ASCE 7-05 with pressure coefficients from page 100 Figure 6-18A ( ASCE 7 -05 )
for my case h/L = 0.627358491
Roof Angle = 0
How to consider load cases as per Figure 6-18 A ,Anyone done wind load as per these open roof like these ?

2. Can i consider Figure 6- 21 for wind load calculation ?

Attached my staad model

Thanks in advance!

 

[JAE]

We would use Figure 6-18A for the pressures on the roof surface itself.
For any vertical columns supporting the roof, we'd use 6-21 as there is some pressure on the vertical column surfaces.

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[fatihash]

Thank u Jae ,
I will use these coefficients but could u plz tell me as there are 2 cases in Fig 6-18
for roof angle 0 degree - clear wind flow and obstructed flow

 

[JAE]

I think ASCE 7 defines two conditions for open structures as "clear" and "obstructed".

In the footnotes of the tables they define "clear" as a relatively unobstructed wind flow with blockage less than or equal to 50%
And obstructed denotes objects below the roof inhibiting wind flow >50% of the area below the roof.

You have to use your own judgement on this as to what objects may occur under the roof.

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