I've had little need to get into modifying structures, but it has finally happened, and looking at the Part Builder information for the structure is confusing. Rectangular structure, rectangular top slab, rectangular frame -- pretty basic I would think.
The situation I've got is that the top of the structure needs to be at 199.50, and the top of the outer wall of the pipe is at 198.30. C3D insists om forcing the top of the structure to 199.99.
Looking into Part builder the relevant distance appear to be 'Vertical Pipe Clearance", SVPC. That is defined under Model Parameters hierarchy as SSTH+SBPC. SSTH is set to 3", and SBPC set to 6". So I'm expecting that the sum of those would be 9" - at least according to the arithmetic I learned in 1st grade. And if 9" is the number being used, then I should not have any problem setting top of structure where I need it.
But, according to the Size Parameters list of values, SVPC is 20.0000, and SBPC somehow is changing to 18.0000
wtf?