You can use a general beam section with tapered cross-section: http://130.149.89.49:2080/v6.11/books/usb/default.htm?startat=pt06ch28s03alm13.html

Dear Spyros Arvanitis

For complex objects with variable cross-sections, I recommend sketching the object in AutoCAD then import the object into the Abaqus.

this is the easiest way for all kinds of complex shapes.

I suggest using a brick element (3D) rather than a beam element and of course, it will require very fine mesh.