YES. The loading requirement of “Rooftop Structures” has been revised in ASCE 7-10.

 
Essentially, buildings less than 60-ft still have the requirement that their wind load be multiplied by a GCr factor applied to the wind pressure that can be as high as 1.9. This has been in place since the 2007 version of the standard (ASCE 7-05). A new section, section 29.5.1, also requires that a GCr uplift factor as high as 1.5 be applied to the top of the rooftop structure in combination with the lateral force. It is also EXTREMELY IMPORTANT for Florida design professionals to note that the 2010 Florida Building Code requires an even higher GCr of 3.1 be utilized for buildings of all heights, not just buildings 60-ft or less.The uplift forces are also required to be in combination with the lateral forces for all buildings in Florida and for use with the International Building Code.
 
Per The FBC/IBC 1609.8 Rooftop Structures and Equipment:

The lateral force on rooftop structures and equipment with Af less than (0.1Bh) located on buildings of all heights shall be determined from Equation 29.5-1 of ASCE 7 in which the value of GCf shall be taken as 3.1. GCf shall be permitted to be reduced linearly from 3.1 to 1.1 as the value of Af is increased from (0.1Bh) to (Bh). The value of G from Section 26.9 of ASCE 7 shall not be used. Additionally, a simultaneous uplift force shall be applied, given by Equation 29.5-1 of ASCE 7 in which GCf= 1.5 and Af is replaced by the horizontal projected area, Ar, of the rooftop structure or equipment. For the uplift force GCf shall be permitted to be reduced linearly from 1.5 to 1.0 as the value of Ar is increased from (0.1BL) to (BL).

 

 

Mar 7, 2016   1155    Codes & Standards    
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