On behalf of colleague, Scott Hampton:
This question relates to ASCE7-22 (the information related to the question below is displayed the same in ASCE7-16, except the Section, figure, and equation numbers have changed).
This question relates to Table 30.10-1 (Steps to Determine C&C Wind Loads for Circular Bins, Silos, and Tanks)
1) The last bullet of Step 3 indicates, “Internal pressure coefﬁcient (GCpi); see Section 26.13 and Section 30.11.3.
a. Section 30.11.3 should be 30.10.3.
b. Is the reference to Section 26.13 (probably more so Table 26.13-1) meant to be applicable to only the internal pressure coefficients for an Enclosed Building? That is, the internal pressure coefficients for Partially Enclosed Buildings should not be used with an Opened-Topped Silo?
c. Rationale –
i. Section 30.10.3 is specifically for Opened-Topped Silos. Equation 30.10-5 produces internal pressure coefficients significantly different than the ±0.55 of Table 26.13-1, and always negative.
ii. The Table 26.13-1 internal pressure terms are specifically defined with reference to ‘Building’ walls with openings. Perhaps some variant of a silo, bin, or tank will have opens in their walls, but in most cases, the only opened part of a silo, bin, or tank will be the roof.
d. Section 30.10.3, in the title, applies to only isolated silos, bins, or tanks. Why are there no internal pressures indicated for Grouped silos, bins, or tanks?