Урок 4.11

Текст A

SABAH FOUNDATION HEADQUARTERS,

KOTA KINABALU, SABAH, MALAYSIA

Suspended by umbrella trusses at two levels from a circular core, this building is 32-storey.

The floors are circular in plan, the office space surrounding a reinforced concrete core which consists of two connected circular walls, approximately 1 ft (300 mm) thick. Thirteen floors are hung off each of the two umbrella structures, each floor being supported at 24 points around its perimeter by hanging bars which reduce in size or number at each floor level going down. The floors are reinforced concrete slabs using 24 radial beams supported by the hanging bars at one end and the core at the other end. Each umbrella structure consists of 24 steel triangular trusses. The core is supported by a concrete raft 9 ft 3in (2.82 m) deep and 68 ft (20.72 m) across resting on 232 steel piles. The building is clad in a reflective glass.

Half the floor load at each level is supported by the hanging bars, taken up to the umbrella and there transferred to ground down the core. With two umbrellas, instead of one, this load path is relatively short but still longer than in conventional column construction. All the wind loads, as well as the gravity loads, are taken by the core acting as a cantilever. Compared to a conventional arrangement, where outside columns taken to ground would be used instead of the hanging bars, the gravity load in the core of the hanging building is doubled and either the vertical prestress doubles or, if the wall thickness is doubled, the section modulus doubles.

After construction of the mat foundation, the slipforming of the 376 ft (115 m) high core walls started. The top umbrella was constructed at ground level and raised by twelve 150 ton (138 tonne) jacks placed at the top of the core. The 24 hanging bars were attached to the umbrella at one end and to the preassembled nineteenth floor, the lowest floor supported by the top umbrella at the other end. After being raised to the top, the umbrella was fixed in position and the construction of floors continued upwards from the nineteenth floor, with traditional formwork. The procedure was repeated for the lower half of the building. Floors are built up to 1³/₄ in (44 mm) high at the perimeter to allow for elastic extension of the hanging bars and the shortening of the core, these two deformations being additive.

Notes:

elastic extension упругое удлинение

hanging bar навесной стержень

load path линия нагрузки

section modulus момент сопротивления сечения

slipforming n. бетонирование в скользящей опалубке

umbrella truss ферма в форме зонта