[Steely Dan]

^ yes, noise transference is more of an issue in residential towers, where there are more likely to be situations when you have people creating a lot of noise and others in the building want quiet, hence more concrete usage for residential towers. however, steel framing can be used for residential towerrs and other methods of noise transference reduction can be employed.

also, reinforced concrete, with it's shorter strucutral bays, and hence denser column grid, is also easier to work a residential program into and around than a commercial office program, which requires large column free clear-span spaces, which steel framing is better suited to accomodate.

there is also the issue of the narrow height-to-width ration of this tower. all things being equal, a conventional reinforced concrete structural system will sway less in the wind, due to the inherent weight of the mass of the material, than a conventional steel framed strucutre.

as for the fire issue, both office and residntial highrises must meet stringent fire-saftey code requirements, so that is not a determinant factor in the use of concrete or steel. the one advantage concrete offers is that it is fire resistant by its own nature, whereas steel construction requires additional fire protective measures, such as spray applied fire proofing and other methods.