Lecture 5 Form Active: Suspension and Cable Stayed

Four Types of Structures (H. Engel)

Form Active

Vector Active

Section Active

Surface Active

Tension Support Structures Span structures (one way) that use tension members to support a roof or floor fall into one of two

categories:

suspension structures and cable stayed structures

A suspension structure is a hanging tension member, usually curved and flexible, whose shape conforms to the funicular shape corresponding to the magnitude and placement of the loads it supports. For example, a suspension bridge has a flexible cable supporting a uniform horizontal distribution of vertical loads. Its funicular shape is a parabola.

A cable stayed structure uses straight tension members, usually flexible cables or rods, to support rigid spanning elements such as beams, either at the ends or at points along the beams length. The tension element carries most of the vertical load of the span while the beam acts as a compression member resisting the horizontal pull of the cable. Stayed cable structures generally have straight tension members while suspension structures have curving tension members. The funicular shape of a tension member carrying a concentrated load is a straight line. History and Evolution

65 iron chain suspension bridge in Yunnan, China 79 rope supported fabric roof over the Roman Coliseum 1420 Thang-Stong rGyal-Po: iron chain bridges in the Tibet 1595 Fausto Veranzio drawings of suspension bridges 1741 Iron chain footbridge in Durham County, England 1801 James Findley: deck-stiffened suspension bridge. Jacobs Creek, USA (21m) 1826 Thomas Telford: Menai Strait chain link bridge in Wales (177m) 1883 John Roebling: steel cable Brooklyn Bridge in New York (486m) 1896 V. Shookhov: Nijny Novgorod exhibition pavilion Tibet 1420 1931 Othmar Ammann: George Washington Bridge in New York (1067m) 1934 E. Beaudouin & M. Lods: Exhibition Hall, Paris (430m) 1937 Joseph Strauss: Golden Gate Bridge in San Francisco, CA (1281m) 1940 Failure of the Tacoma Narrows Bridge, Washington State, USA (862m) 1953 Matthew Nowicki: Arena, Raleigh, NC, USA (95m) 1956 Lev Zetlin: Municipal Auditorium, Utica, NY, USA (74m) 1964 Kenzo Tange: National Olympic Gymnasium 1967 Frei Otto: Montreal Expo Pavilion, Canada (140m) Jacobs Creek 1801

Cable Suspension Bridge Veranzio 16thC Cable Stayed Bridge

Hall 26 INMOS Microprocessor Factory Example of a suspension roof structure: roof profile is the Example of a cable stayed roof structure. Cable stays attach to and support funicular form of a suspended uniformly loaded structure. long span roof trusses at the third point locations of the span.

Suspension structures

Menai Straits Bridge Thomas Telford 1826 Wales, England (span: 177m)

Brooklyn Bridge John Roebling 1883 New York City (span: 486m) George Washington Bridge Othmar Ammann 1931 (span: 1067m)

Golden Gate Bridge Joseph Strauss 1937 San Francisco, CA (span: 1281m)

Suspension bridge structure carrying dead load of the weight of the bridge. Parabolic shape to suspension cable. Live load on bridge will deform the flexible suspension structure at location of load. A stiff bridge deck structure prevents distortion of the cable by spreading the concentrated load over a wider portion of the bridge span.

Exhibition Hall E. Beaudouin & M. Lods 1934 Paris (430m)

Municipal Auditorium Lev Zetlin, engr. Utica, NY (USA) 1956 (74 m)

Coliseum Matthew Nowicki Raleigh, NC, USA 1953

Dulles Airport Terminal Eero Saarinen Washington, DC ca. 1957

Youth Cultural Center Le Corbusier Firminy, France ca.1958

Types of suspension structure supports

Types of suspension structure supports

Types of suspension structure supports

Federal Reserve Bank Gunter Birkirts Minneapolis, MN (USA) 1973

Stayed structures

19th century truss bridges with tension elements: Bollman Truss & Fink Truss

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Ting Kau Bridge Schlaich Bergermann and Partners Hong Kong 1998

Erasmus Bridge Van Berkel Rotterdam, Netherlands 1999

Case Studies

INMOS Microprocessor Plant Richard Rogers 1982

Renault Distribution Headquarters Foster and Partners 1983

Lowara Factory Administration Building Renzo Piano 1985

Covered Parking Structure ca. 2002

Hall 26 Hanover Expo Thomas Herzog 1996

INMOS Microprocessor Factory Richard Rogers Partnership / Anthony Hunt, Engr. Newport, UK ca. 1982

Renault Distribution Center Foster & Partners Swindon, England 1983

Lowara Office Building Renzo Piano Building Workshop nr. Vicenza, Italy 1985

Covered Parking Structure ca. 2002

Hall 26 Hanover Expo-Trade Show Thomas Herzog, arch - Jorg Schlaich, engr Hanover, Germany 1994 - 1996

Competition Brief: 25,000 - 30,000 m2 important criteria: load bearing structure for long spans minimum height roof with high points to enhance natural ventilation daylight preferred, direct sunlight restricted use of renewable materials and savings in energy use

Natural light: external sun screening on south faade and roof triple glazing with light reflecting grids

mirrored soffit

Artificial lighting: lights on sides of glass ducts projected upward and reflected off mirrored ceiling lights on sides of glass ducts projecting downward suspended lighting in strip along underside of ceiling

Diagram showing interior air supply, movement and exhaust. Speed of air moving across the roof is increased by venturi effect of air foil on top of each tower. As air rises the sloping form of roof channels heated air to the highest point where it is released to exterior.

View of interior showing underside of roof with wood panel components, sky-lighting and reflective treatment of ceiling. Note the limited penetration of direct daylight on south facing window wall to the right.

View of tie-down cables to prevent roof flutter due to uplift force of wind. Top: Primary structure: suspension elements and towers

Middle: Modification of side structural bays for support of side enclosure

Bottom: Secondary wood panel roof structure spanning between suspension elements at 5.6m o.c.

Horizontal section showing pre-tensioned back to back steel channels. Vertical section showing 80mm x 50mm faade rail.

Transformation diagram of structure span.

1 Conventional frame solution.

2 Suspension structure supported on columns.

3 Buttresses or cantilevered columns to resist overturning moment.

4 Use of cable tie-backs. Eliminates bending in vertical mast supports.

5 Use of trussed towers to resist overturning moment.

6 Horizontal framing element to stiffen tower at mid-height.

7 Use of horizontal trusses at ends of suspension element to collect closely spaced suspension members and distribute force horizontally to widely spaced towers.

8 Reverse orientation of towers to facilitate additional spans. Interior ties to prevent uplift and flutter of the roof membrane.

Reference

Structures. 6th ed. D. Schodek and M. Bechthold. Pearson-Prentice Hall, 2008. See Ch. 5: Cables and Arches.

Shaping Structures: Statics. Waclaw Zalewski and Edward Allen. John Wiley, 1998. See Ch. 7 Fanlike Structures

Masted Structures in Architecture. James B. Harris and Kevin Pui-K Li. Butterworth, 1996.