ASCE-7 '02 External Pressure Coefficient 2

[rook1]

Im making a program for wind calculation..
In Figure 6-6(con't), in getting the value of Roof Pressure Coefficient Cp, where do you get the value of Cp when Roof Angle is than 10 and h/L is between 0.5 and 1.0?
Since the table shows only values of h/L <=0.5 and >=1.0
Help much appreciated!

 

[WillisV]

You would use a linear interpolation between the values provided for less than or equal to h/L of 0.5 and greater than or equal to h/L of 1.0. For instance if you have an h/L of 0.75 then the Cp for distances from 0 to h/2 from the edge would be midway between -0.9 and -1.3 (-1.1).

 

[chichuck]

I agree with WillisV, to a point.

You would have to do four linear interpolations,

1) for dist from windward edge 0 to h/2 Cp = -1.1 or -.18
2) for dist from windward edge h/2 to h Cp = -0.8 or -.18
3) for dist from windward edge h to 2h Cp = -0.6 or -.18
4) for dist from windward edte > 2h Cp = -0.4 or -.18


ALso, note that the first one can have a reduction factor applied to the interpolation number for the high side (h/L = 1.0; Cp = -1.3) based on effective area; this reduction does not apply to the interpolation number on the low side (h/L = 0.5; Cp = -0.9)

regards,


chichuck

 

[rook1]

Thanks!
thats what i did for now.. Interpolate for the upper, interpolate for the lower.. then interpolate again..