  We consider quantum effects of gravitational and electromagnetic fields in
spherically symmetric black hole spacetimes in the asymptotic safety scenario.
Introducing both the running gravitational and electromagnetic couplings from
the renormalization group equations and applying a physically sensible scale
identification scheme based on the Kretschmann scalar, we construct a quantum
mechanically corrected, or quantum improved Reissner-Nordstrom metric. We study
the global structure of the quantum improved geometry and show, in particular,
that the central singularity is resolved, being generally replaced with a
regular Minkowski-core, where the curvature tensor vanishes. Exploring cases
with more general scale identifications, we further find that the space of
quantum improved geometries is divided into two regions: one for geometries
with a regular Minkowski-core and the other for those with a weak singularity
at the center. At the boundary of the two regions, the geometry has either
Minkowski-, de Sitter-, or anti-de Sitter(AdS)-core.
