  In this work, we construct a new model for the collisional evolution of the
main asteroid belt. Our goals are to test the scaling law of Benz and Asphaug
(1999) and ascertain if it can be used for the whole belt. We want to find
initial size-frequency distributions (SFDs) for the considered six parts of the
belt (inner, middle, 'pristine', outer, Cybele zone, high-inclination region)
and to verify if the number of synthetic asteroid families created during the
simulation matches the number of observed families as well. We used new
observational data from the WISE satellite (Masiero et al., 2011) to construct
the observed SFDs. We simulate mutual collisions of asteroids with a modified
version of the Boulder code (Morbidelli et al., 2009), where the results of
hydrodynamic (SPH) simulations of Durda et al. (2007) and Benavidez et al.
(2012) are included. Because material characteristics can significantly affect
breakups, we created two models - for monolithic asteroids and for
rubble-piles. To explain the observed SFDs in the size range D = 1 to 10 km we
have to also account for dynamical depletion due to the Yarkovsky effect. The
assumption of (purely) rubble-pile asteroids leads to a significantly worse fit
to the observed data, so that we can conclude that majority of main-belt
asteroids are rather monolithic. Our work may also serve as a motivation for
further SPH simulations of disruptions of smaller targets (with a parent body
size of the order of 1 km).
