September_1971 — Page 31

the building are resisted perpendicular- ly to the slope.

(2) A continuous foundation on the slope absorbs any components of the weight of the building which re- sults from no vertical response of the soil. The compressive forces due to this inclined supporting action are transferred to the base foundation of the Vpl.

The most probable foundation at the bottom of the slope consists of the use of piles. Inclined piles, in addition to vertical piles, may absorb any hori- zontal thrust transmitted through the shallow foundation strip on the slope resulting from no vertical response of the slope to mass Vsl. Thus, the soil on the slope reacts in the most efficient manner. Deep and consequently ex- pensive foundations are not required.

The front volume of the building with a load of Vpl is positioned on the base plane to meet accessibility re- quirements of heavy equipment in construction. The vertical and inclined piles absorb the vertical load Vpl and any horizontal components resulting from the compressive action of the foundation strip on the slope when poor soil properties cannot resist the component of the weight Vsl parallel to the slope.

Soil response: Inherent in the ap- proach are two balanced masses which are statically related according to the bearing capacity of the soil. The base plane mass and the slope mass each contribute in varying degrees to the overall statical relationship; emphasis on one mass over another is only de- pendent on the relative soil capacity.

Three conditions may be outlined which delimit the basic relationship:

o allows high loading conditions

oforce distribution relative to soil capacity o high slope utilization

ostandard mechanical systems

ocentralized access

ono vertical duplication

ono despoliation of slope

ostandard construction methods and equipment ono heavy equipment on slope

(1) Relatively poor soil response: proportionally more forces from the sliding component of the gravity loads are transferred to the base plane mass.

(2) Relatively good soil response: proportionally less force from the sliding component of the gravity loads are transferred to the base plane mass.

(3) Relatively balanced response: no relative disproportionate transfer of forces.

Circulation

Primary to the concept is mechani- cal vertical circulation system in the central position of the building. Pedes- trian circulation extends out into the mass of the building from this central

access.

Two basic systems of cross move- ment may be developed:

(1) Horizontal pedestrian circula- tion on each level; no major internal vertical access.

(2) Horizontal pedestrian circula- tion is staggered on the 5th and 6th levels. These levels become the internal street system and may be developed into social activity spaces.

Secondary vertical circulation is developed internally to service clusters of dwellings. These secondary vertical elements may also serve as fire escapes. By the use of the secondary internal network, zones of activity may then be reinforced in the circulation scheme.

Primary to the external system is access from the base plane or, in a modified form, from the plateau or ridge areas.

Vertical mechanical access need not be duplicated because the shape allows groupings of the elevator shafts

STRUCTURAL

CIRCULATION

CONSTRUCTION

for central access to all parts of the building.

Construction

This process can be in the follow- ing sequence:

(1) Preparation of the base plane to allow the positioning of the piles is done with a minimum of contact with the slope.

(2) The piles are driven to accom- modate the vertical load of Vpl and the sliding component of the volume on the slope.

(3) The first level is built on the piles, which then becomes the plat- form for the next level above. In this example, a parking area is generally located in the base level.

(4) The compression spine may be slip-formed up the slope; no heavy machinery is needed for work on the slope.

(5) The circulation and utility core is next erected using slip-forms. De- pendent on the system of construc- tion, the core may be used to position a hoist mechanism for the vertical lift capacity.

(6) The building levels continue to build upon the preceding floors till the completion of the building.

In many situations the mass of the building on the slope may extend fur- ther than the reach of the normal hoist systems. Alternatives to a solution are all within the realm of current con- struction procedures.

Many methods are being used cur- rently in construction for the horizon- tal movement in building. For the system proposed where each preceding floor becomes the circulation base, the following horizontal systems are pro- posed:

(1) A light, movable portal crane may be used in conjunction with a standard lift system. The major central crane on the base plane would retain control of the major lift functions while the portal crane would be used for movement of lightweight materials and equipment for horizontal delivery.

(2) Delivery to all points on the site may be developed using an over- head cable hoist system for both hori- zontal and vertical modes. Inherent in this approach is a base plane anchorage (the circulation/utility core) plus a station for the cable at the top of the slope. In-situ concrete, precast ele- ments, and steel frame construction may all be handled via this system.

(3) The use of two cranes would be

Far East BUILDER, September 1971

25