  Some dynamical aspects of five-dimensional supergravity as a Chern-Simons
theory for the SU(2,2|N) group, are analyzed. The gravitational sector is
described by the Einstein-Hilbert action with negative cosmological constant
and a Gauss-Bonnet term with a fixed coupling. The interaction between matter
and gravity is characterized by intricate couplings which give rise to
dynamical features not present in standard theories. Depending on the location
in phase space, the dynamics can possess different number of propagating
degrees of freedom, including purely topological sectors. This inhomogeneity of
phase space requires special care in the analysis.
  Background solutions in the canonical sectors, which have regular dynamics
with maximal number of degrees of freedom, are shown to exist. Within this
class, explicit solutions given by locally AdS spacetimes with nontrivial gauge
fields are constructed, and BPS states are identified. It is shown that the
charge algebra acquires a central extension due to the presence of the matter
fields. The Bogomol'nyi bound for these charges is discussed. Special attention
is devoted to the N=4 case since then the gauge group has a U(1) central charge
and the phase space possesses additional irregular sectors.
