I need information on the ways a skyscraper can be built, does it have to be built up in one go or can the building be built in phases? please help!!!!

• ID# 266.2 (reply to #266.1) - 21 January 2006
  Indeed a good question. Generally, it should be entirely possible, provided that the loads of any additional floors have been taken into account in the original foundations and structural frame. Then it is a case of building the frame for the new floors above the existing one, provided, of course, that the zoning allows the added bulk or height (and in some cases, that the environmental review of the new bulk's impact on the neighbourhood is passed). Even in cases where the original development rights of the site have been exhausted, obtaining of additional development rights through newly-acquired air rights, for example, could allow an expansion.
  A good example of second-phase construction is the ongoing completion of the Hearst Magazine Building, 80 years after the base of the building was finished. At the same time, the base has been undergoing restoration. The "perpetually uncompleted" Metropolitan Life Insurance Co. Building Annex, on the other hand, has a base frame that could carry (at least) all the 100 floors of the original design, even though it at the present carries less than a third of its designed height. Random House Tower and Park Imperial is an example of "bridging" the difference of a frame in the lower portion with that above it. The steel frame of the lower floors had to be joined with a concrete frame of the top, while none of the columns in the two frames met head-to-head. A complex array of transfer trusses and girders extend through two floors to transfer the loads.
  So, building a skyscraper in two goes is fully possible, although it's undoubtedly easier in terms of logistic and construction continuity to go all the way to the top, rather than establishing a construction site twice and keeping the tenants (if there are any during the reconstruction) satisfied amidst a construction site. ED.