Hi Omar,
The lines you see are a result from "meshing" the object within the IFC file.
Typically to date, IFC data has been used for coordination, so only two shape representations are commonly used, straight extrusions and mesh (Faceted breps). These are sufficient for coordination and clash detection, but limit the process of actually sharing and editing your model in other software.
The IFC geometry specification is based on STEP (similar to that used in IGES) and it is capable of containing advanced shape representations (refer my post here:
http://geometrygym.blogspot.com/2010/12/ifc-shape-representations.html )
You'll have to seek confirmation from Solidworks if if can export more advanced shapes, and then check if Archicad can recognize them.
Hope this helps you understand,
Jon