June_1966 — Page 58

OVERSEAS PROJECT

A

COMPUTERISED CONSTRUCTION

US$66 MILLION development un- der construction on the banks of the Potomac River in Washington, is one of the most unusual and com- plicated building projects ever under- taken in the United States. Known as Watergate, the project may well be- come a classic example of the use of the computer in construction.

When complete Watergate will en- compass five buildings; three co-oper- ative apartment buildings, an office building, and a residential hotel. They will be interconnected underground by a four-tier labyrinth of stores, restaur- ants and parking garages.

The complex is characterised by graceful curves and free-flowing lines that sprang from the imagination of Roman architect, Luigi Moretti. Translating this design into working drawings would have been a Her- culean task without the aid of elec- tronic data processing equipment.

The first building. Watergate East, is now completed. A 13-storey apart- ment, its J-shape curvature is deter- mined by 21 different radii, with some centres of circles located out in the

An arc of the first apartment block

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Electronic data processing speeds engineering design and construction of US$66 million development

Potomac. No two floors are exactly the same and only eight could be considered typical. The differences in balconies and the apartments them- selves meant that few points could be transferred from even a typical floor to another typical floor.

There are no continuous straight lines anywhere, horizontally on the floors or vertically on the facade. Not only are there many different curves on every floor, but no two floors have a facade exactly alike.

These differences meant that sub- contractors had to furnish 2,200 wall panels in 100 different sizes and shapes, and 80,000 sq. ft. of window walls in 596 sizes and shapes. It meant that co-ordinates had to be cal- culated separately for each segment

of each curving wall on each floor. plus CO- ordinates for the vary- ing balconies. Compli- cating matters even further were circular and elliptical rooms in the apartments, inter- rupted corridors, and daily changes that de- manded floor plan re- visions.

Using conventional methods, Matz, Childs and Associates, the consulting engineers, took more than six weeks to determine the curves just for Water- gate East's second floor, where the apart- ments begin. At that rate. it would have taken many months to get detailed specifica- tions ready for the con- tractors. The consul- tants thus turned to En- gineering Physics Co., Rockville. Maryland, a scientific service bu- reau with an IBM 1620 computer. Using

a modified version of COGO, a civil engineering programme for solving geometry problems, the computer re- calculated the second floor curves in eight hours of machine time. On the second. simpler phase of Watergate

the office building and residential hotel the computer calculated co- ordinates in minutes.

Input to the computer consisted of the number of panels desired in а curving section, the co-ordinates for the centre of the curve, and the co- ordinates for the columns in that sec- tion, Using COGO, which was stored in an IBM 1311 disk storage unit, the computer calculated all co-ordinates and distances along the curve. plus any necessary angles. The normal version of COGO is capable of stor- ing 100 co-ordinates, but the pro- gramme was modified so that thou- sands of co-ordinates could be stored.

Printouts from the computer were sent to individual contractors as in- structions.

Layouts Redrawn

By using the computer design changes could be made and layouts redrawn without wearing out the staff. At one stage it was decided to re- locate a balcony on one of the apart ments. To do this, 15 bays (spaces between columns) had to be recom- puted to arrive at new radii. Revised co-ordinates for the centre of curves were sent to the computing facility. where the complete curves were com- puted overnight on the 1620 and the results delivered the next morning. Small sectional layout sheets were then drawn and appended to the originals.

Engineering Physics also wrote a programme for the 1620 when the project engineers had to translate the architect's ideas into six reflecting pools, three of them shaped like seg- ments of an ellipsoid. Finding sur- face points to guide the erection of concrete forms was a relatively simple task once the programme was written. A computer also entered into the

Far East Architect & Builder June, 1966