Anchor bolt load, leg supports 1

[JOHNPIA2]

Compress has modified the standard 'Jawad' formula from P=48M/(N*BC)-W/N, to P=48M/(N*BC)-(0.6-014Sds)*W/N, or P=48M/(N*BC)-0.6*W/N+Vv/N, when the IBC Code is used. I have not found any explanations in their manual; could somebody shed a light on this?
Thanks.

 

[TomBarsh]

This modification is due to application of load combinations 7 and 8 from ASCE 7, paragraph 2.4 (ASCE 7 is the basis for wind and seismic requirements of IBC). These load combinations reduce the structure weight to 60% but apply full bending moment due to wind or seismic.

In my personal opinion, this requirement is more appropriate for office buildings and similar structures where the dead load (DL) of the structure may vary over the life of the structure due to remodeling, etc. Whereas for a pressure vessel the weight (DL) is predictable to a high degree of accuracy and is unlikely to change appreciably over the life of the vessel (the DL will change with corrosion, but again this condition is part of the specified design and can be closely considered).

In a recent discussion I was told that one of the PIP standards ("Process Industry Practices"...

http://www.pip.org)

stipulated that these specific load combinations of ASCE 7 should not be applied to pressure vessels. I haven't had time to track this down myself.

COMPRESS provides the option to disable consideration of these load combinations. See the Set Mode Options dialog, Calculation tab.

Tom Barsh
Codeware Technical Support