wind loads on elevated conical roof

huangyhg

wind loads on elevated conical roof
we are reviewing an existing crushed ore stockpile canopy; a 90m diameter and 30m high cone, with its base elevated some 15m above ground level supported by 12 columns equispaced about the circumference.  the structure is of bolted/welded steel construction with purlins and sheeting for roofing.
the australian wind loading code doesn't specifically address this case, so to calculate the wind loads we have used the net pressure coefficients for a pitched free roof (with cases for blocked and empty under, depending on the stockpile height) with a shape factor of 0.67 to account for the circular shape (in plan) presented to the wind.
does anyone know of a design/loading code or technical paper that addresses the wind loading on such a structure/shape?