Note that the standard German term is actually "(Rückstellungen für) Sachstrukturmaßnahmen", rather than "Sachstrukturaufwendungen".

This conclusion is based firstly on the German KPMG book I referred to in my discussion entry ("Sachstrukturmaßnahmen"), and secondly on other sources, e.g.

http://www.managementcircle.de/weiterbildung/11-65874web.pdf
(note here, too, the distinction between "Personalstrukturmaßnahmen" and "Sachstrukturmaßnahmen")

and

http://www.dfs.de/dfs/internet_2008/module/press/gb2010_de.p...

where we find on p. 76:

"Die Rückstellung für Restrukturierung umfasst Personalstruktur- und Sachstrukturmaßnahmen, für die wegen der Aufgabe von betrieblichen Bereichen kein zukünftiger wirtschaftlicher Nutzen mehr erwartet wird."

This is the same formulation found by Steffen in his discussion entry (ThyssenKrupp).

What this indicates is that the "Sach" here doesn't refer to Sachanlagen (Sachanlagevermögen), i.e. PPE/tangible fixed assets, but to the same common distinction that we find in German accounting between "Personalkosten/Personalaufwendungen" and "Sachkosten/Sachaufwendungen", i.e. "personnel costs/expenses" and "non-personnel operating costs/expenses".

It's also clear that the "Struktur" refers to "restructuring", which is why provisions are being recognised in the first place.

So these "Sachstrukturaufwendungen" are those costs to exit an activity (aka restructuring expenses) that are not directly attributable to personnel expenses (which for discontinued operations would mainly be severance payments/redundancy scheme, retraining and/or relocation expenses, possibly additional early retirement costs, continuing healthcare costs, and so on.)