  In the conventional theory of planet formation, it is assumed that
protoplanetary disks are axisymmetric and have a smooth radial profile.
However, recent radio observations of protoplanetary disks have revealed that
many of them have complex radial structures. In this study, we perform a series
of $N$-body simulations to investigate how planets are formed in protoplanetary
disks with radial structures. For this purpose, we consider the effect of
continuous pebble accretion onto the discontinuity boundary within the
terrestrial planet-forming region ($\sim0.6$ AU). We found that protoplanets
grow efficiently at the discontinuity boundary, reaching the Earth mass within
$\sim10^4$ years. We confirmed that giant collisions of protoplanets occur
universally in our model. Moreover, we found that multiple planet-sized bodies
form at regular intervals in the vicinity of the discontinuity boundary. These
results indicate the possibility of the formation of solar system-like
planetary systems in radially structured protoplanetary disks.
