How can I drop a Bspline Curve into simpler geometry such as polygons, lines, arcs, etc.?This is not possible with the regular Drop Element tool
To drop a Bspline Curve, you must use the Facet Curve tool.
In MicroStation CONNECT Edition the tool is locates here (Drawing Workflow>Curves Tab>Curve Utilities Ribbon Group>Facet)
Using this tool, Bspline Curves can be dropped to Line Strings, Lines, Stream Curves, Arcs, and Points.
In MicroStation V8i the tool can be found from Tools>Curves>Curve Utilities>Facet Curve.
***TIP: When you have the Facet Curve tool active, click F1 on keyboard, and you get MicroStation Help opened for the help of that specific tool.***
Facet Curve - Online Help Doc