Cable-Net Structures

nisee


	*National Information Service for Earthquake Engineering* *University of California, Berkeley*


	Starting with the roof for the German Pavilion at the 1967 Montreal Exposition, Leonhardt, Andrä and Partners have designed numerous cable-net roofs and similar structures, such as the first cable-net cooling tower.

GERMAN PAVILION AT THE 1967 MONTREAL EXPOSITION
(1967-68)



	H96. Overall view.


	Total covered roof area 8,000 square meters, supported by eight masts with a maximum height of 38 meters. Translucent roof cover, supported by a net of strands 12 millimeters diameter, mesh width 50 centimeters in both directions. Strands connected to edge-ropes of 54 millimeters diameter by especially designed clamps. Edge-ropes fixed to the towers and tensioned at foundations. Foundations anchored with prestressed rock anchors.

Design by R. Gutbrod and Frei Otto.

Structural design, consultant for model-testing, wind-tunnel testing and test-roof (in collaboration).

Ref: Leonhardt, F., Egger, H. and Haug, E.: “Der Deutsche Pavilion auf der Expo’67 Montreal - eine vorgespannte Seilnetz-Konstruktion (The German Pavilion at the 1967 Montreal Exposition - a Prestressed Cable-Net Structure),” Der Stahlbau 37 (1968), pp 97-106 and 138-145.



	H97. Model. In the center, the main stadium.


	H98. Indoor pool with 80-m high outside-standing tower. In the background, the Olympic Village.

OLYMPIC-ROOF, MUNICH
(1968-71)

The largest tent-like roof to date, covering a total area of 74,800 square meters and consisting of the roof of the main stadium (34,550 square meters), the gymnastics arena (21,750 square meters), the indoor pool (11,900 square meters), a large (5,800 square meters) and a small (800 square meters) intermediate roof.
All roofs have translucent plexiglas covering and are supported by a network of twin strands with a mesh width of 75 centimeters.
The roof for the stadium is supported by eight cable-stayed towers, tower height up to 76 meters, and tensioned by a curved cable consisting of 10 parallel-strand cables along the inner edge.
The roof of the gymnastic arena is supported by four cable-trusses that are anchored to cable-stayed towers up to 70 meters high.
The roof of the indoor pool is supported by a single 80-meter high tower.



	H99. Interior of indoor pool.


	H100. Stadium, overall view. Note that the floodlights are also supported by the tent-like roof.

Design by G. Behnisch, architect, and Frei Otto, conceptual design.

Structural design, development of analytical procedures for determination of cable forces. Wind-tunnel testing. Development and testing of new structural elements such as parallel-strand cable, clamps and anchors (in collaboration). Computer program for geometry by J. Argyris and K. Linkwitz.

From numerous papers written on this structure, only on reference is given:

Ref: Leonhardt, F. and Schlaich, J.: “Vorgespannte Seilnetzkonstrucktionen - Das Olympiadach in München (Prestressed Cable-Net Structures - The Olympic Roof at Munich),” Der Stahlbau 42 (1973), pp 51-58, 80-86, 107-115, 176-185.



	H101. Stadium, detail of cable connections.


	H102. Stadium interior. In the background, the Munich Television Tower.

CABLE-NET COOLING TOWER AT SCHMEHAUSEN
(1967-68)

Natural draught cooling towers are normally designed as concrete shells for wet cooling, that is, the water flows down inside the tower and is cooled by the ascending air.

These towers consume large quantities of water and the escaping vapor may condense as ice in winter, thereby endangering the traffic in the vicinity of the tower. As a consequence, modern cooling towers are designed as dry towers, with the water running through pipes. In these towers the heat-exchange is by radiation, hence they are larger than towers designed for wet cooling.

As the size of concrete towers cannot be increased arbitrarily due to stability problems, J. Schlaich (former partner of Leonhardt, Andrä and Partners) developed cable-net cooling towers, which with increasing size, become more economic than concrete towers. The main structural elements of this new type of cooling tower are:

The center concrete mast, which may also be used as a chimney.
The upper compression ring with suspension cables fixed to the mast and stiffened by locked coil ropes.
The intermediate tension rings.
The three-directional net of aluminum-covered strands.
The 1-mm thin aluminum skin cladding fixed to the net.

Cable-net cooling towers can easily be built with heights up to 300 meters and to contain nuclear power plants. In this way, the plants are protected from impacting aircraft.

Development of the structural system. Preliminary and final design of the first cable-net cooling tower at Schmehausen.

References:

Schlaich, J. and Mayr, G.: “Naturzug Kühlturm mit vorgespanntem Membranmantel (Natural Draught Cooling Tower with Prestressed Membrane Skin),” Der Bauingenieur 49 (1974), pp 41-45.

“Suspended Net of Cables Forms Nuclear Plant’s Cooling Tower,” Engineering News Record, October 30, 1975, pp 16-17.

Schlaich, J. and Mayr, G.: “Membrane Skin and Cable-Net Cooling Towers,” Preliminary Report IABSE 10th Congress, Tokyo, 1976, pp 33-38.

Schlaich, J., Mayr, G., Weber, P. and Jasch, E.: “Der Seilnetzkühlturm Schmehausen (The Cable-Net Cooling Tower at Schmehausen),” Bauingenieur 51 (1976), pp 401-412.


	H103. Cable-net cooling tower at Schmehausen. Height of concrete mast 180 meters, of tower 146 meters. Diameter of tower 92 meters at top, 82 meters minimum, 141 meters at base.

	The University of California, Berkeley Copyright 1997, The Regents of the University of California. Structural Engineering Slide Library, W. G. Godden, Editor Set H: Structures of Leonhardt, Andrä and Partners