Appendix E API 650 Convective and Impulsive acceleration

[PauPower]

A calculation is performed according to appendix E with peak acceleration "Sp" and also is tried with design spectral response parameter Sa, Sa0, Sa*. In all cases the result is that impulsive accelaration is less than convective acceleration, Ai<Ac. According to equation E.4.6.1.4 impulsive shall be higher. API is not indicating in that case how to proceed, Do we have any alternative?, How we can solve it?

Soil type: SE
Sp=0.34g
Importance factor: 1

Dimensions:
D=7410mm
Shell Height=7500mm
Liquid level= 7200mm

 

[JStephen]

I don't have the standard here in front of me, but the equation I'm remembering is an equation that says Ac = "XXXX" < Ai. The intent is that you calculate the "XXXX" part but that Ac need not exceed Ai, so if it calculates higher, then just set Ac = Ai.

This would be kind of unusual, so it'd be an indication to double check everything.