As such could be considered this paper on community structure of the US Congress and Senate
, penned by Mark Newman
(et al). This paper insvestigates the mesh of committees and subcommittees of both houses of representatives considering them as nodes, and common membership as edges, and finds relation to the political organizations represented in them.
I don't know if that study would reveal anything in Spain; I don't even know if that information is available. In Spain votes go along party lines, and it's quite uncommon (even unheard of) to have a representative vote against the other members of their party. I don't know what importance do these committees have here, anyways. I guess not much.