Using full building height (h>60ft.) to calculate C&C wind suction load

[SuG89]

Hello,

Refer to the attached extract from ASCE 7-10. I was wondering what's the reason for using full building height (variable 'h') to calculate the wind suction loads on component and cladding elements (which let's say are attached to the building on ground floor). This results in very high values in comparison to wind pressure where the code allows to use the actual height (variable 'z'). Could anyone please explain this to me?

Regards,
Su

 

[JAE]

If you read through the commentary for this chapter, you don't get a direct answer to your question but you do get the understanding that the procedure was based on wind tunnel tests developing an envelope result. In one part of the commentary here they even talk about the internal pressure using the actual height, z, instead of the total height, h, to avoid too much conservatism in the design. For leeward pressures, I guess I'd assume that the wind tunnel tests showed that the peak variability of small area C&C wind pressures mandated the use of h.



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[SuG89]

JAE,

Thank you very much for responding to my question. I'll look into the commentary.

Regards,
Su