Sir

Is there any option in PVElite to increase the allowable stresses in Zick Analysis as per UG-23(d) (ASME Sec. VIII, Div. I) in case of occasional loads like earthquake or wind loading etc.

Regards
Saurabh Gajwani

Hello Saurabh

The stress increase for occasional loads apply to loads that - as the name suggest - are occasional. Generally speaking, the weight of the vessel and its design contents are sustained loads.

Where seismic and wind loads are added to the sustained loads, it is permissible to use the higher stresses. However, our software takes the conservative approach, and does not use the occasional load factor when saddle supports are considered.

We do consider the occasional load factor in the design of towers, where the stresses can be increased (by the occasions load factor). This is particularly important, as thicknesses might otherwise be over sized.