Because of its location between two existing buildings, and to accommodate the Lebanese law of setback requirements, the geometry of the 42-storey Sky Gate residential development in Beirut is particularly unconventional. The structure is made up of four cubical elements which are offset from right to left from levels 10/11 to 17/18 and then again from 20/23 to the roof to create four superimposed blocks.
The ‘stagger’ of the two middle blocks is supported by a cantilever system of post-tensioned beams designed and installed by post-tensioning specialist CCL, and located at each block’s lowest and highest level. A further two cantilevered beams support the offset of the fourth, and at 20 levels, the largest block. This challenging project required particular care during construction to cater for the eccentricity resulting from the vertical offset of the blocks. By stressing the transfer beams at levels 10/11 in phases, CCL was able to remove the need for propping right down to the basement levels and so reduce the cost of shoring.
Sky Gate is situated in the uppermost point of Beirut, in the Achrafieh district, making it the highest building in the city. The structure is situated between two adjacent buildings for the first 24 levels. Above this point it provides 360 degree views of Beirut for all floors.