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Tube (structure)
Encyclopedia
In structural engineering
, the tube is the name given to the systems where in order to resist lateral loads (wind, seismic, etc.) a building is designed to act like a three-dimensional hollow tube, cantilever
ed perpendicular to the ground. The system was introduced by Fazlur Rahman Khan
while at Skidmore, Owings and Merrill
's (SOM) Chicago office. The first example of the tube’s use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building in Chicago, Illinois
, completed in 1963.
The system can be constructed using steel
, concrete
, or composite construction (the discrete use of both steel and concrete). It can be used for office, apartment and mixed-use
buildings. Most buildings in excess of 40 stories constructed in the United States since the 1960s are of this structural type.
perpendicular to the ground. In the simplest incarnation of the tube, the perimeter of the exterior consists of closely spaced columns that are tied together with deep spandrel
beams through moment connections. This assembly of columns and beams forms a rigid frame that amounts to a dense and strong structural wall along the exterior of the building.
This exterior framing is designed sufficiently strong to resist all lateral loads on the building, thereby allowing the interior of the building to be simply framed for gravity loads. Interior columns are comparatively few and located at the core. The distance between the exterior and the core frames is spanned with beams or trusses and intentionally left column-free. This maximizes the effectiveness of the perimeter tube by transferring some of the gravity loads within the structure to it and increases its ability to resist overturning due to lateral loads.
. Fazlur Khan
defined the framed tube structure as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or near their edges to form a vertical tube-like structural system capable of resisting lateral forces in any direction by cantilevering from the foundation." Closely spaced interconnected exterior columns form the tube. Horizontal loads, wind for example, are supported by the structure as a whole. About half the exterior surface is available for windows. Framed tubes allow fewer interior columns, and so create more usable floor space. Where larger openings like garage doors are required, the tube frame must be interrupted, with transfer girders used to maintain structural integrity.
The first building to apply the tube-frame construction was the DeWitt-Chestnut apartment building which Khan designed and which was completed in Chicago
by 1963. This laid the foundations for the tube structural design of many later skyscrapers, including his own John Hancock Center
and Willis Tower, and the construction of the World Trade Center
, Petronas Towers, Jin Mao Building
, and most other supertall skyscrapers since the 1960s.
's DeWitt-Chestnut apartment building, designed by Khan and completed in 1965, but the most notable examples are the Aon Center
and the destroyed World Trade Center towers.
s are introduced along the exterior walls to compensate for the fewer columns by tying them together. The most notable examples incorporating steel bracing are the John Hancock Center
, the Citigroup Center
and the Bank of China Tower. When the outer columns are insuffient to support the load, interior cores can be used. 780 Third Avenue on Manhattan, a 50-story concrete frame office building, is an example of using concrete shear walls for bracing while also incorporating an off-center core.
.
The bundle tube design was not only highly efficient in economic terms, but it was also "innovative in its potential for versatile formulation of architectural space. Efficient towers no longer had to be box-like; the tube-units could take on various shapes and could be bundled together in different sorts of groupings." The bundled tube structure meant that "buildings no longer need be boxlike in appearance: they could become sculpture."
Structural engineering
Structural engineering is a field of engineering dealing with the analysis and design of structures that support or resist loads. Structural engineering is usually considered a specialty within civil engineering, but it can also be studied in its own right....
, the tube is the name given to the systems where in order to resist lateral loads (wind, seismic, etc.) a building is designed to act like a three-dimensional hollow tube, cantilever
Cantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...
ed perpendicular to the ground. The system was introduced by Fazlur Rahman Khan
Fazlur Khan
Fazlur Rahman Khan was a Bangladeshi born architect and structural engineer. He is a central figure behind the "Second Chicago School" of architecture, and is regarded as the "Father of tubular design for high-rises"...
while at Skidmore, Owings and Merrill
Skidmore, Owings and Merrill
Skidmore, Owings and Merrill LLP is an American architectural and engineering firm that was formed in Chicago in 1936 by Louis Skidmore and Nathaniel Owings; in 1939 they were joined by John O. Merrill. They opened their first branch in New York City, New York in 1937. SOM is one of the largest...
's (SOM) Chicago office. The first example of the tube’s use is the 43-story Khan-designed DeWitt-Chestnut Apartment Building in Chicago, Illinois
Illinois
Illinois is the fifth-most populous state of the United States of America, and is often noted for being a microcosm of the entire country. With Chicago in the northeast, small industrial cities and great agricultural productivity in central and northern Illinois, and natural resources like coal,...
, completed in 1963.
The system can be constructed using steel
Steel
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten...
, concrete
Concrete
Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...
, or composite construction (the discrete use of both steel and concrete). It can be used for office, apartment and mixed-use
Mixed-use development
Mixed-use development is the use of a building, set of buildings, or neighborhood for more than one purpose. Since the 1920s, zoning in some countries has required uses to be separated. However, when jobs, housing, and commercial activities are located close together, a community's transportation...
buildings. Most buildings in excess of 40 stories constructed in the United States since the 1960s are of this structural type.
Concept
The tube system concept is based on the idea that a building can be designed to resist lateral loads by designing it as a hollow cantileverCantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...
perpendicular to the ground. In the simplest incarnation of the tube, the perimeter of the exterior consists of closely spaced columns that are tied together with deep spandrel
Spandrel
A spandrel, less often spandril or splaundrel, is the space between two arches or between an arch and a rectangular enclosure....
beams through moment connections. This assembly of columns and beams forms a rigid frame that amounts to a dense and strong structural wall along the exterior of the building.
This exterior framing is designed sufficiently strong to resist all lateral loads on the building, thereby allowing the interior of the building to be simply framed for gravity loads. Interior columns are comparatively few and located at the core. The distance between the exterior and the core frames is spanned with beams or trusses and intentionally left column-free. This maximizes the effectiveness of the perimeter tube by transferring some of the gravity loads within the structure to it and increases its ability to resist overturning due to lateral loads.
History
By 1963, a new structural system of framed tubes had appeared in skyscraper design and constructionSkyscraper design and construction
The design and construction of skyscrapers involves creating safe, habitable spaces in very tall buildings. The buildings must support their weight, resist wind and earthquakes, and protect occupants from fire. Yet they must also be conveniently accessible, even on the upper floors, and provide...
. Fazlur Khan
Fazlur Khan
Fazlur Rahman Khan was a Bangladeshi born architect and structural engineer. He is a central figure behind the "Second Chicago School" of architecture, and is regarded as the "Father of tubular design for high-rises"...
defined the framed tube structure as "a three dimensional space structure composed of three, four, or possibly more frames, braced frames, or shear walls, joined at or near their edges to form a vertical tube-like structural system capable of resisting lateral forces in any direction by cantilevering from the foundation." Closely spaced interconnected exterior columns form the tube. Horizontal loads, wind for example, are supported by the structure as a whole. About half the exterior surface is available for windows. Framed tubes allow fewer interior columns, and so create more usable floor space. Where larger openings like garage doors are required, the tube frame must be interrupted, with transfer girders used to maintain structural integrity.
The first building to apply the tube-frame construction was the DeWitt-Chestnut apartment building which Khan designed and which was completed in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
by 1963. This laid the foundations for the tube structural design of many later skyscrapers, including his own John Hancock Center
John Hancock Center
John Hancock Center at 875 North Michigan Avenue in the Streeterville area of Chicago, Illinois, is a 100-story, 1,127-foot tall skyscraper, constructed under the supervision of Skidmore, Owings and Merrill, with chief designer Bruce Graham and structural engineer Fazlur Khan...
and Willis Tower, and the construction of the World Trade Center
Construction of the World Trade Center
The construction of the World Trade Center was conceived as an urban renewal project, spearheaded by David Rockefeller, to help revitalize Lower Manhattan. The project was developed by the Port Authority of New York and New Jersey, which hired architect Minoru Yamasaki who came up with the specific...
, Petronas Towers, Jin Mao Building
Jin Mao Building
The Jin Mao Tower is an 88-story landmark supertall skyscraper in the Lujiazui area of the Pudong district of Shanghai, People's Republic of China. It contains offices and the Shanghai Grand Hyatt hotel. Until 2007 it was the tallest building in the PRC, the fifth tallest in the world by roof...
, and most other supertall skyscrapers since the 1960s.
Variations
From its conception, the tube has been varied to suit different structural requirements:Framed tube
This is the simplest incarnation of the tube. It can take a variety of floor plan shapes from square and rectangular, circular, and freeform. This design was first used in ChicagoChicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
's DeWitt-Chestnut apartment building, designed by Khan and completed in 1965, but the most notable examples are the Aon Center
Aon Center (Chicago)
The Aon Center is a modern skyscraper in the Chicago Loop, Chicago, Illinois, United States, designed by architect firms Edward Durell Stone and The Perkins and Will partnership, and completed in 1973 as the Standard Oil Building...
and the destroyed World Trade Center towers.
Trussed tube
Also known as the braced tube, it is similar to the simple tube but with comparatively fewer and farther-spaced exterior columns. Steel bracings or concrete shear wallShear wall
In structural engineering, a shear wall is a wall composed of braced panels to counter the effects of lateral load acting on a structure. Wind and earthquake loads are the most common loads braced wall lines are designed to counteract...
s are introduced along the exterior walls to compensate for the fewer columns by tying them together. The most notable examples incorporating steel bracing are the John Hancock Center
John Hancock Center
John Hancock Center at 875 North Michigan Avenue in the Streeterville area of Chicago, Illinois, is a 100-story, 1,127-foot tall skyscraper, constructed under the supervision of Skidmore, Owings and Merrill, with chief designer Bruce Graham and structural engineer Fazlur Khan...
, the Citigroup Center
Citigroup Center
The Citigroup Center is one of the ten tallest skyscrapers in New York City, United States, located at 53rd Street between Lexington Avenue and Third Avenue in midtown Manhattan...
and the Bank of China Tower. When the outer columns are insuffient to support the load, interior cores can be used. 780 Third Avenue on Manhattan, a 50-story concrete frame office building, is an example of using concrete shear walls for bracing while also incorporating an off-center core.
Bundled tube
Instead of one tube, a building consists of several tubes tied together to resist the lateral forces. Such buildings have interior columns along the perimeters of the tubes when they fall within the building envelope. Notable examples include Willis Tower and One Magnificent MileOne Magnificent Mile
One Magnificent Mile is a mixed-use high-rise tower completed in 1983 at the northern end of Michigan Avenue on the Magnificent Mile in Chicago containing upscale retailers on the ground floor, followed by office space above that & luxury condominium apartments on top.Height: 673 ft / 205 m Total...
.