Upvote:4
Although far from exhaustive, I suggest using Wikidata. There are 168 items with "architectural style" property set to "brutalism".
In addition, the list of brutalist structures in Wikipedia seems more complete than Wikidata. The equivalent list in German may be worth checking because it could contain more structures than the English one - or at least some different ones.
In fact, if you plan to collaborate to expand a database about brutalist architecture, Wikidata and Wikipedia are great places.