The interior of the units was lined with insulation and wall finish. The majority of the components such as bathrooms and kitchens were pre- made and installed as complete units into the box before the roof was connected.
The modular units are incorporated into the structure in such a way that adjacent walls, floors, and ceilings of neighbouring houses are separated, thus a high level of sound and vibra- tion insulation is achieved.
In grouping the units, gardens are formed on the roof of the unit below (the large ones measuring 17 ft. x 36 ft.). All houses have at least one garden, and the large houses have two gardens.
Other elements in the structure such as pedestrian streets, elevator cores, stairs, were also precast in the yard and erected by crane. The crane was a stiff-leg derrick supported by a 70 ft x 70 ft. base, which in turn moved on a track 70 ft. wide.
Structural System
The modular units are load bear- ing. They are erected one on top of the other, carrying the major part of the load through walls and piers. Further structural support is given by the horizontal streets. These streets are 10 ft. high and contain the me- chanical services within them and the pedestrian circulation on top of them.
SRIDGE
DOMINIO
A portion of the loads is transmit- ted from the boxes to these streets horizontally to the vertical elevators and stair cores. In addition, overall stability for wind and seismic condi- tions is provided by the action of house units and streets. The house units are connected to each other by post-tensioning and bolting, and the street units themselves are constructed of sections which are post-tensioned to form one unit.
The houses are centrally heated and air conditioned. Each box contains all plumbing and electrical services in a sub-floor space. Also housed in this space is a fan-coil unit which is sup- plied with cool or hot water from the central plant, depending on the sea- son. This is then converted to warm or cool air which is distributed through thin slots at the edge of the floor.
House types are achieved by dif- ferent combinations of one, two, or three box units thus a variety of house types results, both of one or two storeys in height. All gardens are provided with planters. These are automatically irrigated and fertilized from a central source.
The houses have been designed as self-contained units with their own plumbing and service connections, so that they may easily be sold as in- dividual units using the condominium method, now commonplace Europe and South America.
Complete 90-ton housing unit being hoisted into position
Far East Architect & Builder June, 1967
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Habitat rests on pile foundations. For the most part piles are end-bear- ing, wet-driven, concrete bulbs which are encased and unreinforced. These are mainly 13 in. dia. (70-ton cap- acity), 16 in. (100-ton), or 19 in. (150- ton). In addition, 70 tension piles were needed to resist uplift forces during earthquakes. These are also bulb piles but are 24 in. dia.. not en- cased, and reinforced with an extra heavy cage of rebars. Design load for these is 34 tons tension and 70 tons compression,
piles
Clusters of high-capacity were needed at the lift shafts and stairwells to take the concentrated loads coming from the street girders. Thirty 150-ton piles have been driven at three of these locations. In all, the foundations contain 1,121 piles.
Precasting Techniques
Production of the boxes was car- ried out in a 58,000 sq. ft. on-site precasting plant which was itself pre- cast, and could be dismantled and moved when the job was complete.
Besides the boxes, other precast components close to 3,000 separ- ate pieces in all, including street girders, staircases, roof slabs and lift cores were made in this plant.
Precasting accounted for three quarters of the 50,000 cu. yd. of con- crete work on the project, the remain- ing quarter being taken up by foot- ings, foundation walls, and a concrete slab at plaza level.
First stage of their production was the assembly of the rebar cages. Each cage was built in three steps, using specially designed jigs, in a section ad- jacent to the casting moulds.
First, the crews assembled the small units such as columns and floor level perimeter beams. These were tied and lightly tack-welded to maintain flexibility within the jig. Next, these pieces were assembled into walls, us- ing a second jig. The post-tensioning rods used to tie the boxes together when assembled were positioned at this stage.
Finally, the separate walls were brought together to form the full, three-dimensional reinforcing cage. using a third, specially designed jig.
Mild steel rebars with 20,000 p.s.i. working stress and ultimate stress of 40,000 p.s.i. were used throughout. High tensile steel with an exception- ally high ultimate strength of 160,000 p.s.i. was used for the vertical post- tensioning rods. When complete, the cage was carried in one piece by a 50-ton capacity wheeled "travellift" to the casting area.
Casting was done in one of four identical moulds. Each mould consist- ed of reinforced steel outer wall-forms. A low slump rapid-curing con- crete with a maximum of 4 in., was used. Air entrainment additives gave the mix 3-4 per cent. air, and the concrete was specified to reach minimum strength of 5.000 p.s.i. at 28 days. Steam curing was employed. In full operation, the casting plant produced 10 boxes a week,
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