Issues related to the seismic design of oil tanks per GB50341-2014
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In Appendix D of GB50341-2014, regarding the seismic design of oil tanks, in clause D3.5, the calculation of the fundamental period of coupled vibration of the tank’s contents involves δ1/3; the document specifies that this value refers to the thickness at 1/3 of the height of the tank wall and bottom plate； Does GB50341-2003 refer to the effective thickness? What causes the change? Additionally, when calculating the anchorage coefficient J, it is necessary to determine the parameter μ; what value should be used if αmax is less than 0.45? That is, how should the value be determined when the region is at 6 degrees or 7 degrees? Please give me some advice.
Regarding this 1/3 height, it appears three times in GB50341; in D.3.5, δ1/3 is defined as the calculated thickness at the point on the tank wall that is 1/3 of the way up from the bottom plate； In note D.3.5 (page 207), δ1/3 refers to the wall thickness of the tank at 1/3 of the liquid level height ； On page 210, there is a discrepancy between the statements regarding the wall thickness at the upper part of the δ1/3 1/3 tank. Personally, I think it should be the effective thickness, because when calculating seismic resistance, the wall thickness of the steel plate is already determined. If calculated according to clause D.4.2, the μ for 7 degrees and 0.1g is greater than 1, around 1.015. However, I believe that a value of 1 should be used for 6 and 7 degrees, meaning no correction is necessary. For reference only.