No_1_June_1963 — Page 103

18

UILDING: A VERTICAL ASSEMBLY LINE

THE

HE ‘JACKBLOCK method of construction was devised and is being used in the construction of a 17-storey block of flats for the Coventry Corporation in England. Richard Costain (Construction) Ltd. started work on this prototype early in 1962. and the building is scheduled for completion this sum

mer.

A feature of the Jackblock' sys- tem is that the vertical supporting construction of the building is jacked up. Starting with the roof slab at ground level. the floors are connect- ed to the rising supporting construc- tion, one by one, and are raised in sequence until the whole building reaches its final position. In short. the building, starting with the roof. is extruded from a low level 'work- shop.'

square

At Coventry the supporting struc- ture consists of walls forming

But Jackblock core.

is

flexible enough to permit of its use in the construction of buildings dif fering on plan; aesthetically, too, it has possibilities in offering freedom of design to the architect. Another example of its use is Britannia House. a 14-storey office block in the centre of Brussels. where work is due to start shortly.

By doing the work at low level and then jacking up the completed floors, Costain propose to eliminate many of the difficulties of multi- storey building. It is in the con- struction of tall buildings, particu- larly 17 storeys and higher. that *Jackblock" can be used to greatest advantage. The erection of the 17- storey block of flats at Barras Heath, for the Coventry Corporation (Arthur Ling, city architect) is an example which may be given to describe the method of operation.

Two further phases during construction.

The supporting walls form a square core in which services, lifts and staircases are housed. The floors cantilever outwards from the four walls. In the floor construction there is a 'double cross" of four pretensioned main beams supported directly on the walls of the core These main beams are infilled with secondary concrete beams, while the remaining openings are covered in with prefabricated floor-slabs.

The foundations consist of a rein- forced concrete slab. in this case supported on piles. Constructed on this is the jacking chamber which contains 40 jacks. each of 220 tons lifting capacity placed in the position of the supporting walls. The roof of the jacking chamber forms the floor at ground level, and also serves as a temporary floor shutter for all the subsequent floors. There are slots in the ground floor through which the supporting walls pass. Finally

THE HONG KONG & FAR EAST BUILDER ·

FEREENI

VOLUME 18, NUMBER 1

97