I’ve tested on three maps, caucasus, nellis and marianas on the current dcs release version.
Caucasus map structures, from smallest residential to large buildings, are impervious to any kind or amount of aerial or ground fire (except for the light brown structure labelled ‘garage’, this is the only thing that can be destroyed that I have found so far in this latest update). This was testing with as many as 12 1500kg bombs dropped directly and accurately on the structure by 4 ai su-34s. No fire, no effect at all, just the visible blast from initial impact.
On the Nellis map, map structures respond correctly to been struck by aerial ordnance. I destroyed chinatown pretty handily in the testing with nothing bigger than fab500s. Though artillery fire only seems to effect parked map cars and other minor street objects…hmmm.
On the marianas map, only small single residence residential structures seem to be destroyable. For example, a small two story office type structure labelled ‘shop’ at the olf orote port withstood 24 fab500s from 4 ai j-11s. Other small warehouse type structures withstood multiple similar hits as well. Though they burned, at the end, they were all intact with no visible damage. However, at nearby lockwood terrace, multiple single residential structures were destroyed by a single pass by a j-11 with 4 fab500s.