With a total under construction area of 530,000sqm, Kingdom Tower in Jeddah, Saudi Arabia by Design Architect Adrian Smith + Gordon Gill Architecture (AS+GG) will be the tall building to go where no building has gone before – beyond 1,000 meters.
A mixed-use building featuring a luxury hotel, office space, serviced apartments, luxury condominiums and the world’s highest observatory, Kingdom Tower is both highly technological and distinctly organic.
The project once completed, will feature a high-performance exterior wall system that will minimize energy consumption by reducing thermal loads and features a series of notches that create pockets of shadow shielding the building from the sun. The great height of Kingdom Tower necessitates one of the world’s most sophisticated elevator systems. The complex will contain 59 elevators, including 54 single-deck and five double-deck elevators along with 12 escalators. Elevators serving the observatory will travel at a rate of 10m/sec in both directions. Another unique feature of the design is a sky terrace, roughly 30m in diameter at level 157.
The Y-shaped plan with 120-degree separation between wings allows for views to be expansive but not directed toward adjacent units and provide a higher ratio of exterior wall to internal area to give residential units’ maximum exposure to light.
The shape also allows the spreading of the base of the tower without increasing the depth of the lease-span. This means that the building can still maintain a reasonable 10:1 height to width ratio without having a large amount of unusable deep internal space. The triangular core thus formed by the shear walls is also very good at resisting wind induced torsion. Having three legs, the plan naturally has at least three stairs. With its continuous, reinforced concrete shear walls, those stairs are completely enclosed within a very robust and secure environment, providing the life safety system of the tower, the minimum required fire separation and effective sound-control mechanism between public and private spaces.
Tower continuous taper to each wing eliminates the need for outrigger transfers and belt trusses at certain locations, which in turn reduces the concentration of structural loads as well as permits an uninterrupted construction process. Furthermore, having different rates of taper to each wing results in different termination heights for each, thereby creating the dramatically distinct three-part spire of the Tower.
The structure for the Kingdom Tower is comprised entirely of castin-place reinforced concrete walls, coupling beams and conventionally reinforced flat plate concrete floor framing. The structure contains no outriggers or wall/column transfers.
Due to the continuous and uninterrupted vertical nature of the walls for the tower, a highly efficient jump form system can be utilized. Formwork for the floor slabs also can be reused due to the highly repetitive geometry of the tower. The faces of the shear walls are all vertical, with the exception of the ends of each wing, which taper to follow the form of the Tower. This can be accomplished by a simple shift of between 200 and 300 millimeters for each 4m vertical lift or internal block-outs in formwork that is lifted vertically. Because the ends of the shear walls slope, the taper at the end of each wing is created by a consistent 3.5m cantilever extension of the slab edge. Entire building envelope notching is achieved by simply dropping off slab edge cantilevers.
The foundations for the tower are a raft supported on bored circular piles located approximately 2.5 meters below existing grade due to site modifications raising the base of the tower. This modification minimizes the amount of potential dewatering required on the site during construction of the lower levels.