; ; ; ; ; Civil Engineering Blog: PONDING CONSIDERATIONS IN BUILDINGS

keywords

Most popular categories
free niche civil engineering software jobs degree course manual powerpoint calculation sheet books finite element concrete steel environment ACI AASHTO PCI Transportation Railsway Logistics nuclear FRP strengthening repair material price Earthquake Bridge Train Home Building Factory GPS GIS Survey Structural Engineering
------------------------------------------------------------------

Thursday, September 30, 2010

PONDING CONSIDERATIONS IN BUILDINGS

PONDING CONSIDERATIONS IN BUILDINGS

 


Flat roofs on which water may accumulate may require analysis to ensure that they are stable under ponding conditions. A flat roof may be considered stable and an analysis does not need to be made if both of the following two equations are satisfied:
C p + 0.9 C s £ 0.25
I d ³ 25S 4 / 10 6
Where C p = 32 L s L 4 p / 10 7 I p
C s = 32 SL 4 s / 10 7 s
L p = length, ft (m), of primary member or girder
L s = length, ft (m), of secondary member or purlin
S = spacing, ft (m), of secondary members
I p = moment of inertia of primary member, in 4
(mm 4 )
I s = moment of inertia of secondary member, in 4
(mm 4 )
I d = moment of inertia of steel deck supported on secondary members, in 4 /ft (mm 4 /m)
For trusses and other open-web members, I s should be decreased 15 percent. The total bending stress due to dead loads, gravity live loads, and ponding should not exceed 0.80F y , where F y is the minimum specified yield stress for the steel.

2 comments: