What's your SU version, and What QGIS version? There used to a shp tool very long ago.
Also have just found this, which may be a solution, or a path to one:
https://forums.sketchup.com/t/importing-shapefiles-shp-to-sketchup-skp/59032/10
I can't help you more than that at moment. Haven't used SU for a while so it looks like folk are still doing interesting things with it.