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Prof. Wolfgang Schueller

The early development of tall buildings occurred in Chicago from about 1880 to 1900, where block- and

slab-like building forms reached 20 stories.

Then the soaring towers of New York introduced the true skyscraper, the symbol of American cities as

reflected by the cityscape with the proposal for the new World Trade Center in New York (2002) by

Rafael Vinoly.

Louis Sullivan integrated masterfully abstract stylistic considerations of tripartite subdivision with the expression of load-bearing in the Guarantee

Building, Buffalo, 1895.

The Gothic style was applied to the Cathedral of Learning at the University of Pittsburgh (mid 1930s) to articulate height of the tower through the upward thrust that is the skyscraper.

The Empire State Building (1250 ft), New York, 1931, Shreve, Lamb, and Harmon - the building does not express the complexity of the building organism as the modernists do

Notice the further development of the faade and appearance as the effect of functionalism in the

resolution of the wall to a transparent weightless skin or the deconstruction of the faade takes place.

Glass skyscraper project, 1920, Mies van der Rohe Bauhaus Dessau, Germany, 1926, Gropius Engineering College, Ningbo Institute of Technology, Zhejiang University, Ningbo, 2002,

Qingyun Ma

Tour Lilleurope, Lille, France, 1995, Claude Vasconi Lloyds Registry, London, 2000, Richard Rogers, Anthony Hunt Library, Ningbo Institute of Technology, Zhejiang University, 2003, Ningbo, Qingyun Ma Administration Building, Ningbo Institute of Technology, Zhejiang U. , Ningbo, 2001, Qingyun

Ma

University Hotel of Ningbo Institute of Technology, Zhejiang University, Ningbo, Qingyun Ma, 2003, clear expression of structure

Dormitory of Nanjing University, Zhang Lei Arch., Research Center of Architecture Tods Omotesanto Building, Tokyo, Japan, 1997, Toyo Ito, network of concrete trees The new generation of high-rise building structures 1, 2

The development of modern building support structures has its origin in the inventive spirit of structural

engineering and the rapid progress in the engineering sciences during the 19th century. The birth of the new

era of high-rise building construction is surely reflected by the unbelievable height of the

Eiffel Tower in Paris, 1889, with 300 m. The exponential shape of the tower is almost funicular as vertical cantilever with respect to lateral wind pressure and as a column with respect to weight (i.e.

equal stress). The tower conveys an understanding of equilibrium forms and expresses clearly

lateral stability with its wide base similar to the base of tree trunks. With the 15-story Johnson Wax Tower (1950) at Racine, Wisconsin, Frank Lloyd Wright

became the first designer to break away from the traditional skeleton concept in high-rise

construction. He used the tree concept, in his urge toward the organic, by letting the mushroom-

type floor slabs cantilever from the central core, which is deeply rooted in the ground. Wright

freely used the plastic quality of concrete and helped to even further identify the potential of the

material.

VERTICAL BUILDING

STRUCTURES

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Influenced by the newly found possibilities of engineering and the spirit of invention, the Russian

Constructivists experimented in the early 1920s or so with different building shapes, the deconstruction

of the building, in other words by taking a completely opposite position to the classical tradition of faade

architecture.The constructivist art of modernism surely has influenced designers. Pioneers such as

Antoine Pevsner and Naum Gabo at the early part of this century in Russia, and later Alexander Calders kinetic art and Kenneth Snelsons tensegrity sculptures.

Monument to the Third International, model designed by Vladimir Tatlin, 1920, experiments with structure, Russian Constructivism

The Shabolovka tower, 1922, Vladimir Shukhov Experiments with structure, Russian Constructivism, El Lissitaky, 1924 Non-right solids, fundamentals of constructivism Early 1960s, glass sculptures of Harry Saeger (2 slides) Ribat, 1979, wood sculpture Picasso sculpture, Chicago, 1967 Mobile, Calder, Hirshorn Museum, Washington Tree of Bowls, Jean (Hans) Arp, Foundation Beyeler, Riehen/Basle, Switzerland, 1960 Kenneth Snelson, Needle Tower, 1968, Hirshorn Museum, Washington; this 60-ft high (18 m)

tower explores the spatial interaction of tension and compression. A network of continuous cables

is prestressed into shape by discontinuous compression struts which never touch each other.

Buckminster Fuller explained tensegrity as tensile integrity, as islands of compression in a sea of

tension.

Vertical building structures range from massive building blocks to slender towers. They may occur as

isolated objects or urban mega structures. This geometrical study: from the single house to the urban

building, suggests the formal variations including

single and cluster houses, free-standing and merging buildings, terraced and inverted stepped buildings, open and closed shapes, and so on.

High-rise building shapes range from boxy, pure shapes (prisms as based on rectangle, cruciform,

pinwheel, etc.) to compound hybrid forms; the high-rise of the postmodern era seem to have complete

freedom of form-giving. The building masses may be broken up vertically and horizontally into

interacting blocks to reduce the scale of the building.

The transition of the high-rise building to the base and its interaction with the urban scale has become has

become an important design consideration.

Building complex in Amsterdam Audi Forum Tokyo, The Iceberg, 2006, Benjamin Warner ING Group Headquarters, Amsterdam, 2002, Meyer en Van Schooten Arch Nord Deutsche Landesbank am Friedrichswall, Hannover, 2002, Behnisch Exchange House, London, 1990, SOM

A building structure can be visualized as consisting of horizontal planes (floor and roof structures), the

supporting vertical planes (walls, frames, etc), and the foundations. The horizontal planes tie the vertical

planes together to achieve somewhat of a box effect, and the foundations make the transition from the

building to the ground possible.

It is obvious that a slender, tall tower must be a compact, three-dimensional closed structure where the

entire body acts a unit. On the other hand, a massive building block only needs some stiff, stabilizing elements that give lateral support to the rest of the building.

The primary load-bearing structure of a building is subdivided into the gravity structure and the lateral-

force resisting structure which resists wind and earthquakes and provides lateral stability to the building.

space organization, SAP2000 tower, steel/concrete frame using Etabs HIGH-RISE APARTEMENT TOWER, Malm, Sweden, 2003, Calatrava, based in form on the

sculpture Turning Torso

Rosenthal Center for Contemporary Art, Cincinnati, 2004, Zaha Hadid

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- The strength and stiffness of a building is very much related to the type and arrangement of the vertical structural elements, as is suggested in this figure. The density and interaction or continuity,

of the elements, together with the degree of symmetry, indicate the degree of compactness of the

structure.

- However, not only the horizontal building cross-section, where the location of the structure is defined, but also the nature of the vertical structures in the vertical section (i.e. elevation of structure)

must be considered as is demonstrated in the drawing for planar structures.

- Introduction to load action - The vertical force flow is investigated in this drawing. Notice that the type and pattern of force flow depend on the arrangement of the vertical structural planes. The path of the force flow may be

continuous along the columns or may be suddenly interrupted and transferred horizontally to another

vertical line. The transmission of the loads may be short and direct, or long and indirect with a detour

as for a suspension building. When columns are inclined, gravity will cause directly lateral thrust,

keeping in mind, continuous rectangular frame action will cause indirect lateral action.

- The building response to lateral load action is investigated in this drawing. The horizontal forces are transmitted along the floor/roof diaphragms, which act as deep flat horizontal beams, to the vertical

lateral-force resisting structures which in turn respond as vertical , flexural or shear cantilevers. - Some considerations related to wind action are studied in this drawing indicating that wind loads are

not simply uniform pressure values as given by codes.

- In this study of the building response to force action, the increase of force flow towards the base is convincingly expressed by the density of the stress trajectories and the truss analogy.

- The high-rise building structure under gravity and lateral load action modeled as an engineering line

diagram.

High-rise structures range from pure structure systems, such as skeleton and wall construction, and

systems requiring transfer structures, to composite systems and mega-structures. As the building increases

in height, or buildings become slenderer, different structure systems are needed for reasons of efficiency,

i.e. a particular structure system is applicable within certain height limits, that is as the scale changes different structure systems are required.

The effect of scale is known from nature, where animal skeletons become much bulkier with increase of

size as reflected by the change from the tiny ant to the delicate gazelle and finally to the massive elephant.

The impact of scale on structure and form is apparent from nature not only with respect to animals but also

plants. For instance, the slenderness height-to-diameter of the wheat stalk is around 500, while it

decreases to 133 for bamboo and to about 36 for a giant redwood tree, clearly illustrating again that

proportions are not constant but change. We may conclude that structure proportions in nature are derived

from behavioral considerations and cannot remain constant. Thus the dimensions are not in linear

relationship to each other; the weight increases much faster than the corresponding cross-sectional area.

This phenomenon of scale is taken into account by the various structure members and systems as well as by the building structure types as related to the horizontal span, and vertical span or height. With increase of

span or height, material, member proportions, member structure, and structure layout must be altered and

optimized to achieve higher strength and stiffness with less weight.

For high-rise steel buildings the efficiency of a particular structure system is measured as the quantity of

material used that is the weight per square foot or the total building structure weight divided by the total

square footage of the gross floor area. The effect of the scale is clearly reflected by the change of weight for

a 10-story braced frame structure from 6 psf to 29 psf (0.29 to 1.39 kPa) for a 100-story tubular structure!

The discussion above refers only to ordinary buildings; special building configuration (in plan and

elevation) and special load transfer conditions obviously cannot be taken into account.

The efficiency of a concrete structure is evaluated to a great extent in terms of process of construction,

in additions to the quantities of materials used that is roughly between 0.5 ft3/ft2 (0.15 m3/m2) to 1.0 ft3/ft2

(0.30 m3/m2) concrete, and reinforcing steel of 2 lb/ft2 (96 Pa or N/m2) to 4 lb/ft2 (192 Pa or N/m2), in

contrast to steel, which considers only the quantity of material used.

Every building consists of the load-bearing structure and the non-load-bearing portion. The main load

bearing structure, in turn, is subdivided into:

Gravity structure consisting of floor/roof framing, slabs, trusses, columns, walls, foundations Lateral force-resisting structure consisting of walls, frames, trusses, diaphragms, foundations

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Support structures may be classified as,

Horizontal-span structure systems: floor and roof structure, enclosure structures Vertical building structure systems 1, 2: walls, frames cores, etc., tall buildings

The following classification is used to discuss the cases in my presentation:

- Bearing wall structures (28 stories) - Core structures (and bridge structures) - Suspension buildings - Skeleton structures and flat slab building structures - Rigid frame (30 stories) - Braced frame structures: frame with shear wall/core (45 stories) - Staggered wall-beam structures (40 stories) - Frame with shear, band and outrigger trusses (60 stories) - Partial tubular systems (65 stories) - Exterior framed tubular (90 stories) - Bundled framed tubes (110 stories) - Exterior diagonalized tubes (115 stories) - Mega-structures - Hybrid structures - The new generation of building types - Unconventional building structures

BEARING WALL STRUCTUES

The bearing wall was the primary support structure for high-rise buildings before the steel skeleton and

the curtain wall were introduced in the 1880s in Chicago. The traditional tall masonry buildings were

massive gravity structures where the walls were perceived to act independently; their action was not

seen as part of the entire three-dimensional building body. It was not until after World War II that

engineered thin-walled masonry construction was introduced in Europe.

Bearing wall construction is used mostly for building types that require frequent subdivision of space

such as for residential application. Bearing wall buildings of 15 stories or more in brick, concrete

block, precast large-panel concrete, or cast-in-place reinforced concrete are commonplace today; they have been built up to the 26-story range.

- 16-story Monadnock Building, Chicago, 1891, John Wellborn Root, clear expression of structure (no decoration0

- Plan forms range from slab-type buildings and towers of various shapes to any combination. The wall arrangements can take many different forms, such as the cross-wall-, long-wall-, double cross-wall-,

tubular-, cellular-, and radial systems.

- The walls may be continuous or perforated to various degree, as is suggested in the study of the effect of lateral load action upon walls with openings.

- Study of gravity force flow along walls The nature of gravity force flow can be visualized as the flow of water which is distributed when an object is submerged in the uniform current thereby displacing the flow lines. The resulting flow net

depends on the type of opening in the wall and support conditions. The degree of disturbance, that is

the crowding of the stream lines, indicates the increased speed or the corresponding intensity of load

action.

- High-rise cantilever walls shown in SAP2000 - Perforated Concrete Wall shown in SAP2000 - 18-story Nederlandse Gasunie, Groningen, 1994, Alberts + Van Huut Arch., is organically shaped to

reflect the constant movement under the change of sun and weather. The slender building, 1:6.7,

consists of load bearing concrete walls anchored front to back by nearly m thick diaphragm walls.

The 60-m glass wall in front, which appears almost like a waterfall, is carried by an enormous steel

space frame covering the atrium space.

- Dormitory of Nanjing University, Zhang Lei Arch., Nanjing University, Research Center of Architecture

- Neuer Zollhof, Duesseldorf, Germany, 1998, Frank O. Gehry

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- Unite dHabitation, Marseille, France, 1952, Le Corbusier, which is 450 ft (137 m) long, 80 ft (24 m) wide and 184 ft (56 m) high and the cross walls are spaced at circa 4 m.

- Typical cross shear wall structure - The behavior of ordinary cross shear walls - Typical long-wall structure - Apartment building, Heerlen, Netherlands, the faade walls are probably not load-bearing - WALDEN 7, 1974. Sant Just Desvern. Barcelona, , Spain, Ricardo Bofill - Visual study of the structure of Walden 7 - LA MURALLA ROJA, 1973. Calpe, province of Alicante, Spain, Ricardo Bofill - Black castle, Spain, Ricardo Bofill - Stufendomino Lyngberg, Bonn- Bad Godesberg, Wetzel Wohnbau, 1975, terraced building - The fractal space of Moshe Safdies Habitat 67 in Montreal, Canada, consists of load bearing precast

concrete boxes which were stacked 12 stories high and are tied together by post-tensioning. The

vertical elevator shafts and stair cores together with elevated horizontal streets give lateral support in

frame action to the asymmetrical assembly.

- Visual study of box-type wall arrangements - Ramot Housing Complex, 1970s,The Cube and the Dodecahedron in My Polyhedric Architecture, Zvi

Hecker

CORE STRUCTURES

Many multi-core buildings with their exposed service shafts have been influenced by the thinking of

the Metabolists of the 1960s, who clearly separated the vertical circulation along cores and the served

spaces. Their urban clusters consisted of vertical service towers linked by multilevel bridges, which in

turn contained the cellular subdivisions. The linear bearing wall structure works quite well for

residential buildings where functions are fixed and energy supply can be easily distributed vertically.

In contrast, office and commercial buildings require maximum flexibility in layout, calling for large

open spaces subdivided by movable partitions. Here, the vertical circulation and the distribution of other services must be gathered and contained in shafts and then channeled horizontally at every floor

level. These vertical cores may also act as lateral stabilizers for the building.

- Study of central core structures

- There is an unlimited variety of possibilities related to the shape, number, arrangement, and location of cores. They range from single-core structures (e.g. core with cantilevered floor framing) to multiple

core structures.

- Shizuoka Press & Broadcasting Center, Tokyo, 1967, Kenzo Tange - Torre de Collserola, Norman Foster, 1992, guyed mast - Knights of Colombus Building (23 stories), New Haven, 1970, Kevin Roche - Marina Towers (179 m, 62 floors), Chicago, 1964, Bertrand Goldberg - Nakagin Capsule Tower, Tokyo, Japan, 1972, Kisho Kurokawa, where prefabricated steel boxes are

clipped onto the exposed concrete service shafts

- Study of core buildings - Federal Reserve Building (33 stories), Boston, 1972, Stubbins Arch, Le Messurier Struct. Eng., 3-story

transfer trusses carry 30 floors to the end cores

- OCBC Center (52 stories), Singapore, 1976, I.M. Pei, Arup,, concrete mega-frame - Herbert F. Johnson Museum of Art, Cornell University, 1973, I. M. Pei, constructivist sculpture - Building, New Delhi, Raj Rewal - Hypobank (21 stories), Munich, Germany, 1981, Walter and Bea Betz - Triangle Building, Friedrichstr/Mauerstr,.Berlin, 1996, Josef Paul Kleihues - Sendai Mediatheque, Kasuga-machi, Aoba-ku, Sendai-shi, Japan, Toyo Ito + Mutsuro Sasaki, 2001;

the transparent facade allows the revelation of diverse activities that occur within the building. Along this main facade the six 15.75-inch-thin floor slabs seem to be floating within the space connected only

by the 13 vertical tube steel lattice columns that rise up from ground floor to roof, similar to the trunks

of trees of a forest. The tubes are both structure and vector for light and all of the utilities, networks

and systems that allow for technological communication and vertical mobility, including elevators and

stairs. Each vertical shaft varies in diameter and is independent of the facade, allowing for a free form

plan which varies from floor to floor.

- Study of Urban Megastructure and Bridge Structuress - Yamanashi Communications Center, Kofu, Japan, 1967, Kenzo Tange - University Clinc (Klinikum), Aachen, Germany, 1981, Weber + Brand

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- Visual study of bridge buildings - The Hong Kong Club and Office Building, Hong Kong, 1983, Harry Seidler, 112-ft (34 m) curved

prestressed concrete girders are shaped according to the intensity of force flow and carry the loads to

four huge S-shaped corner columns

SUSPENSION BUILDINGS

The application of the suspension principle to high-rise construction rather than roof structures is

essentially a phenomenon of the late 1950s and 1960s. The structuralists of this period discovered a

wealth of new support structure systems in the search to minimize the material and to express

lightness allowing no visual obstruction with heavy structural members. The fact that hanging the

floors on cables required only about one-sixth of the material compared to columns in compression,

provided a new challenge to designers. Tree-like buildings with a large central tower, from which giant

arms are cantilevered at the top or intermediate levels, to support tensile columns, are quite common

today. The typical suspension systems use the rigid core principle (single or multiple cores with

outriggers or beams, mega-frames, tree-like frames, etc.), the guyed mast principle, and the tensegrity

or spacenet principle.

- Westcoast Transmission Tower (12 stories), Vancouver, Canada, 1969 - Hospital tower of the University of Cologne, Germany, Fritz Leonardt Struct. Eng. - Lille Europe Tower (115 m), Lille, France, 1995, Claude Vasconi, where the floors are suspended from

a huge cross-beam on top which, in turn, is supported by the end cores

- Study of suspension structures - Standard Bank Centre (35 stories), Johannesburg, South Africa, 1970, Hentrich-Petschnigg - BMW Building (22 stories, 100 m) , Munich, Germany, 1972, Karl Schwanzer - Visual study of the Narcon Building, Hannover, 1984 - Visual study of Olivetti Building (5 floors), Florence, Italy, 1973, Alberto Galardi - Old Federal Reserve Bank Building (83 m, , Minneapolis, 1973, Gunnar Birkerts, 273-ft (83 m) span

truss at top

SKELETON STRUCTURES and FLAT SLAB BUILDING STRUCTURES

When William Jenney in the 10-story Home Insurance Building in Chicago (1885) used iron framing

for the first time as the sole support structure carrying the masonry faade walls, the all-skeleton

construction was born. The tradition of the Chicago Frame was revived after World War II when the

skeleton again became a central theme of the modern movement in its search for merging technology

and architecture. A typical expression of this era are Mies Van der Rohes buildings, which symbolized with their simplicity of expression the new spirit of structure and glass.

- Lake Shore Drive Apts, Chicago, Ludwig Mies van der Rohe, at Chicago, 1948 to 1951 - The drawing of Mies van der Rohes 52-story, 212-m IBM Tower in Chicago (1973) expresses the

structural action and organization of the steel frame; the building is controlled by the grid of 9 x 12 m;

the grid seems almost to subdue the structural action

- National Permanent Building 1775 & 1747 Pennsylvania Avenue, Washington, NW, Hartman-Cox - Visual Study of skeleton structures: although the pure, boxy shapes of the 1960s are closely associated

with skeleton construction, as derived from Miesian minimalism, other building skeleton forms based

on quite different philosophies, have been built.

- Typical skeleton structures in elevation - Frame behavior - The skeleton structure in plan - Beijing Jian Wai SOHO, Beijing, Riken Yamamoto, 2004 - Tsinghua University, 2006 - Ching Fu Group Headquarters, Kaohsiung, Taiwan, 2007, Richard Rogers - The Colonnade (28 stories), Singapore, 2001, Paul Rudolph - Wisma Dharmala Sakti (30 stories), Jakarta, Indonesia, 1988, Paul Rudolph adopted local character

of Indonesian architecture

- Lippo Center (44 floors, 172 m), Hongkong, 1988, Paul Rudolph - The Netherlands Architectural Institute, Rotterdam, 1993, Jo Coenen

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- Visual study of the skeleton as assembly: the various systems can only suggest the infinite variation in which the linear beam and column elements can be formed and related to one another

- Visual study of flat slab building structures: from a behavioral point of view flat slabs are highly complex structures. The intricacy of the force flow along an isotropic plate in response to uniform

gravity action is reflected by the principal moment contours.

BRACED FRAME STRUCTURES

The most common construction method is, to resist lateral force action through bracing; it is applied to all

types of buildings ranging from low-rise structures to skyscrapers. At a certain height, depending on the

building proportions and the density of frame layout, the rigid frame becomes too mushy and may be

uneconomical so that it must be stiffened.

- Visual study of braced frame structure - Housing, Isle of Dogs, London, Docklands, UK, 1989, Campbell etc. - Office Building, Central Beheer, Apeldorn, Holland, 1987, Herman Herzberger - Visual study of shear wall/ core frame interaction systems in plan: typical structures are shown, in

some cases the core is the stiffest element and resists nearly all the lateral loads, in other building the

resistance to lateral force action is shared.

- Example of core frame structure - NTV Tower, Shiodome, 2003, Richard Rogers - Visual study of floor framing systems - Daley Center Building, Chicago, long-span perimeter girders - First National Bank Building (844 ft, 60 stories). Chicago, 1969, C. F. Murphy - Transamerica Pyramid, San Francisco, 1972, William L. Pereira - Example of shear wall resistance for residential construction - The difference in stiffness between frame and braced frame - Shear wall - frame interaction - Steel plate shear walls - Staggered wall-beam buildings: story-high wall beams span the full width of the building on alternate

floors of a given bay and are supported by columns along the exterior walls; there are no interior

columns. One can visualize the apartment units to be contained between the wall-beams and to be

vertically stacked to resemble masonry bond patterns.

- Staggered truss examples - Visual study of faade trussing: lateral bracing of buildings need not to be restricted to internal cores,

shear walls, etc, it may also be expressed on the faade, serving aesthetic as well structural functions

- Century Tower, Tokyo, 1991, Norman Foster - Central Plaza, Kuala Lumpur, Malaysia, 1996, Ken Yeang - Capital Centre, Sydney, Australia, 1989, Harry Seidler - Visual study of faade trussing, introduction to tubular behavior - Turmhaus am Kant-Dreieck mit Wetterfahne aus Blech, Berlin, 1994, Josef Paul Kleinhues - Poly International Plaza (36 stories, 165 m), Guangzhou, China, 2007, SOM - Museum of Modern Art (proposal ?), NY, R. 2004, Rogers - NY Times 15/10/2007:A new 75-story tower designed by the architect Jean Nouvel for a site next to

the Museum of Modern Art in Midtown promises to be the most exhilarating addition to the skyline in

a generation. Its faceted exterior, tapering to a series of crystalline peaks, suggests an atavistic

preoccupation with celestial heights. The irregular structural pattern is intended to bear the strains of

the towers contortions. Mr. Nouvel echoes the pattern of crisscrossing beams on the buildings facade, giving the skin a taut, muscular look. A secondary system of mullions housing the ventilation system

adds richness to the facade.

- High Line (HL) 23, New York, 2009, Neil M. Denari Arch, Desimone Consulting Engineers - Prada Boutique Aoyama Tokyo, Tokyo, Japan,2003, Herzog & de Meuron - Tods Omotesanto Building, Tokyo, Japan, 1997, Toyo Ito, network of concrete trees - Looped Hybrid Housing, Beijing, 2008, Steven Holl Architects - Analysis of frames - Concrete Frame-Shear Wall Interaction: self-weight case - Rigid Frame Shear Wall interaction - Example hinged steel frame braced by concrete shear wall (3 slides) - Bracing systems for tall buildings

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- Hinged frame + core/ outrigger building construction: the stiffness of the structure can be greatly improved by using story-high or deeper outrigger arms that cantilever from the core or shear wall at

one or several levels and tie the perimeter structure to the core by either connecting directly to

individual columns or to a belt truss. This makes the structure act as a spatial structure similar to a

cantilever tube-in-tube.

- Allied Bank tower (71 stories), Houston, 1983, SOM - Trump tower(68 stories), New York, 1982, Swanke Hayden Connel - Visual study of composite building structures

TUBULAR STRUCTURES

As the building increases in height in excess of circa 60 stories, the slender interior core and the planar

frames are no longer sufficient to effectively resist lateral forces. Now the perimeter structure of the

building must be activated to provide the task by behaving as a huge cantilever tube. Much credit for

the development of the system must given to the eminent structural engineer Fazlur Khan of SOM.

Various types of wall perforations and wall framing for tubes are shown in the next figure:

Perforated shell tube (j): concrete wall tube, stressed skin steel tube, composite steel-concrete tube

Framed tube or Vierendeel tube (H) Deep spandrel tube (I) Framed tube with belt trusses (L) Trussed or braced tube (M) Latticed truss tube (N) Reticulated cylindrical tube (O) Combination (K)

Further organization of tubes according to behavior (cross section):

Pure tubular concept: Single-perimeter tubes, tube-in-tube, bundled tubes (modular tubes) Modified tubes: interior braced tubes, partial tubes, hybrid tubes

The Early Tubular Structures

- The behavior of the cantilever tube - Tubular Structures: various types of tubular systems are shown: perforated shell tube (stressed skin

steel tube, concrete wall tube, composite steel-concrete tube), framed or Vierendeel tube, deep spandrel

tube, framed tube with belt trusses, trussed or braced tube, latticed truss tube, any combinations. The

organization according to the cantilever cross-section is: single perimeter tubes, tube-in-tube, bundled

or modular tubes, and modified tubes (interior braced tubes, partial tubes, hybrid tubes)

- Cook County Administration Building (Brunswick Building), Chicago, 1964, Myron Goldsmith (SOM), perimeter tube + interior core

- One Shell Plaza, Houston, 1971, SOM - 780 Third Avenue Office Building (50 stories), New York, 1985, SOM - Alcoa Building (6 stories), San Francisco, 1967, SOM - John Hancock Center (100 stories, 344 m), Chicago, 1968, Bruce Graham/ Fazlur Kahn of SOM - Sears Tower (110 stories), Chicago, 1974, SOM

The Next Generation of Tubular Structures

- Fountain Place (219 m), Dallas, 1986, I.M. Pei, is of elaborate formal geometry where the perimeter trussed steel frame for the lower 40-story portion is the primary support structure

- Bank of America Center (238 m, 56 stories), Houston, 1984, P. Johnson, the tower has the appearance of three adjoining towers, where the tallest tower consist of a perimeter tube closed on the inside with a

Vierendeel hat truss following the gabled roof line that ties the braced frame of the interior core to the

exterior tube; the intermediate tower consists of a channel-shaped partial tube and the low-rise tower

has a planar welded frame along the end face.

- JP Morgan Chase Tower (75 stories, 305 m), Houston, 1982, I.M. Pei, mixed construction - Messeturm (256 m), Frankfurt/M, 1991, Jahn/Murphy, tube-in-tube in concrete, 50% of wind moments

is carried by the perimeter tube

- Petronas Towers (88 stories, 452 m), Kuala Lumpur, Malaysia, 1996, mixed construction, core-outrigger: the towers are each framed by a 152-ft (46 m) diameter concrete perimeter tube connected

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by floor diaphragms to a high-strength reinforced concrete core nearly 75 ft (23 m) square. The core

columns are connected at the corners to the perimeter tube by four reinforced concrete Vierendeel

trusses at the 38th floor above ground. The slenderness of tower is 8.6!

- Jin Mao Building (88 stories, 1380 ft), Shanghai, China, 1999, SOM, recalling the ancient pagoda forms, gently stepping back to create a rhythmic pattern as it rises upward. The tower is organized into

8 segments (considered a lucky number) where each one is reduced in height by 1/8 of the base height. The composite structure comprises a concrete core, 8 concrete mega columns, eight steel columns, and

steel floor framing.

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MEGASTRUCTURES AND HYBRID STRUCTURES

The term megastructure refers not to the visionary concepts of the 1960s expressing the

comprehensive planning of a community, but solely the support structure of a building. However, the

megastructure is still formulated on the basic concept of a primary structure that supports and services

secondary structures or smaller individual building blocks. In the early 1970s, Fazlur Khan proposed

to replace the multicolumn concept by four massive corner column supporting superframe. The principle can be traced back to the John Hanckock Center in Chicago.

Study of new generation of structures (hybrid structures): the current trend away from pure building forms

towards hybrid solutions as expressed in geometry, material, structure layout, and building use, is apparent.

In the search for more efficient solutions for unique conditions, a new generation of structural systems has

developed with the aid of computers which, in turn, have an exciting potential of architectural expression.

Mathematical modeling with computers has made mixed construction possible, which may vary with

building height, thus allowing nearly endless possibilities that one could have not imagined only a few

years ago:

- Hotel de las Artes (154 m, 44 floors), , Barcelona, Spain, 1992, SOM/Iyengar, diagonally braced tube in the form of mega portal frames

- Overseas Union Bank Center (280 m, 63 floors), Singapore, 1986, 280m, Kenzo Tange, hybrid system of steel frames with concrete walls to increase rigidity (the core consists of hybrid steel frame with

concrete wall zones) allowing for column-free floor space.

- Proposal for the new World Trade Center in New York (2002), Rafael Vinoly - Visual study of mega-structures - Examples of mega-structures: the Bank of Southwest Tower (82 storries), Houston, proposal,

Murphy/Jahn + LeMessurier, 1982, similar to Greek cross in plan; Medical Mutual Building,

Cleveland, Stubbins + LeMessurier, 1983

- Citicorp Center (59 stories), New York,1977, Stubbins + William LeMessurier - The Bank of Southwest Tower (82 stories, proposal), Houston, 1982, Murphy/Jahn, LeMessurier - Bank of China Tower (369 m, 70 stories), Hong Kong, 1989, I. M. Pei + L. E. Robertson; space-frame

braced tube organized in 13-story truss modules, where the 170-ft (52 m) square plan at the bottom of the building is divided by diagonals into four triangular quadrants. The mixed construction of the

primary structure consists of the separate steel columns at the corners (to which the diagonals are

connected), which are encased and bonded together by the massive concrete columns. The giant

diagonal truss members are steel box columns filled with concrete.

- Commerzbank (259 m, 60 stories), Frankfurt, Germany, 1997, Norman Foster + Arup, the triangular steel tower has a central atrium where the corner core columns support the Vierendeel trusses which, in

turn, carry the floors and skygarden while allowing column-free interior spaces.

- Visual study of hybrid structures hybrid structures

A NEW GENERATION OF BUILDING TYPES

- Hongkong Bank (180 m), Honkong, 1985, Foster + Arup, steel mast joined by suspension trusses

acting in portal frame action

- Duesseldorf City Gate (67 m, 19 stories), Duesseldorf, Germany, H. Petzinka + Fink Arch (and Ove

Arup for preliminary design of structure), is presented as an introduction to the new generation of

high-rise structures. The 56 m high interior open space atrium is a typical characteristic of this new

generation of urban buildings. The twisted composition of the rhombus-like arched building (circa 51 x

66 m in plan) is laterally supported by two triangular trussed framed core towers or mega-columns

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which are connected to form three portal frames that is a Z-like bracing system in plan view. The steel

pipes of the trussed frames are filled with concrete.

- Shinjuku, Tokyo, Kenzo Tange, 2009

- Messe-Torhaus (116 m, 30 floors), Frankfurt, 1985, O.M. Ungers

- Seoul Broadcasting Center, Seoul, proposal 1996, Richard Rogers Arch. and Buro Happold Struct.

Eng.: the 37-story tower is approximately 90 m long, 18 m wide, and 180 m high from foundation level. The ladder-like macro frame structure with infill framing is laterally braced in the narrow

direction by outrigger buttresses. The mega-trusses support the infill framing from above in

compression and from below in tension. The supper-structure is concrete encased steel, the secondary

structure is steel, and the slabs consist of steel deck and concrete.

- Samsung Life Insurance Jong-Re Building, Seoul, 1999, Rafael Vinoly Arch, Structural Design

Group Co. Ltd, Tokyo, Japan: the 33-story building is about 157 m high from foundation level, 35 m

wide, and 75 m long. It consists of a mega-structure, that is three cylindrical steel cores at the corners

of a triangular plan, which are tied together at the top by a space frame head truss to form a portal

frame, which encloses infill framing in between. The innovative glass curtain (one of the largest in the

world) is suspended on vertical stainless steel rods supported by cantilevered steel brackets at the 11th

floor and uses glass beams (or blades) for support. The 45 m hanging glass and steel curtain comprises

panels 1 m tall and 2.2 m wide. The horizontal glass beams are formed of 5 pieces of tempered glass and span 11 m between columns.

UNCONVENTIONAL BUILDING STRUCTURES

In this study structure types were investigated which were experimental in nature and not derived from the

structure systems idea. They often demonstrate fascinating new structural concepts possibly motivated by

more encompassing design philosophies quite often taken from nature and other visionary schemes:

Paoli Soleri, Pompidou Center, Manfredi Nicolettis helicoidal skyscraper, Carlo Morettis residential tower, etc.

Eric Mendelsohn modeled the Einstein Tower in Potsdam (1930) in the spirit of German Expressionism.

The building form seems to symbolize an optical instrument by using the plastic character of concrete as

the media although brick was used as a substitute material. Naturally, there are no limits to the formal

expression as demonstrated by the LAX Control Tower, Los Angeles, 1995, by Katherine Diamond. This

78 m high tower reflects a high-tech tree-house using structural elements imaginatively but in a somewhat

decorative, fragmented fashion.

- Visual study of unconventional building structures of the 1960s and 1970s

SOME OF THE CURRENT BUILDINGS

- Sony Center am Potsdammer Platz, Berlin, Helmut Jahn, 2000 - Simmons Dorm, MIT, Steven Holl , 1999, Holl focused on a vision of "porous building morphology,"

which called for a row of "permeable" rather than barrier buildings designed with the "sponge" concept

in mind. Taking a conceptually open attitude, the building was envisioned to be open to light and air,

open to undergraduate and graduate students, and open to faculty and artists-in-residence who will live,

work, eat, study, and be entertained within its dynamic spaces. The building stands 10 stories (100 ft;

30 m) high, 385 ft (117 m) long and 53 ft (16 m) deep. It is wrapped almost entirely in a matrix of 5,538 two-ft-sq (0.4 sq m) windows. Though not part of Holl's initial concept, the exoskeleton of the

building is formed by a gridded shell, composed of precast concrete wall panels called Perfcon,

developed specifically for this project. This precast concrete wall panel system serves as part of the

gravity and lateral load resisting system, and essentially provides a bearing wall that accepts a

regular pattern of holes while allowing for major structural variables such as large openings and

cantilevers.

- 178 Mirador, Madrid, Spain, 2004, MVRDV - Lujiazui Financial Center, Shanghai, Gensler Architects - Hearst Tower, New York, 2005, Foster Associates Architects

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- Norddeutsche Landesbank (84 m, 18 floors), Hannover, 2002, Behnisch; The 23-story multiuse tower's stepped-glass profile and giant cantilevers pierce the skyline of the city's Friedrichswall district. In

addition to an intriguing appearance, the building features an environmentally innovative design. A

soil-heat exchanger in the foundation distributes cool air to upper levels, and a daylight-redirection

system is integrated into a glare-eliminating sunshade.

- Swiss Reinsurance Headquarters (180 m), London, 2004, Norman Foster + Arup; Arup have provided an elegant structural engineering response to the building's radical form by creating the 'diagrid' system

of intersecting steel elements around the tower's perimeter. This structure combines vertical support to

the floors and resistance to wind forces, whilst following the curved shape and allowing the lighwells

to spiral up through the building.

- Burj Al Arab (Tower of the Arabs 321 m, 56 stories),, Dubai, United Arab Emirates, 1998, W. S. Atkins; the hotel is constructed on a man-made island approximately 300 m offshore

- HIGH-RISE APARTEMENT TOWER, Malm, Sweden, 2003, Calatrava, based in form on the sculpture Turning Torso

- Phare Tower, La Dfense, Paris. 2006, Thom Maynes (Morphosis, LA) - Skyscrapers. Dubai, United Arab Emirates Thompson, Ventulett, Stainback Arch, Arup Eng., The four

towers: Ranging from 54 to 97 floors designed to represent the movement of candlelight. Over 6

million sq ft of office, hotel, and residential space Base podium of the business district can hold 35,000 automobiles. Each floor plate is unique to itself

- Computer generated image of the Up Town Project in Bahrain - Manama, Bahrain Financial Harbor - Turbine building, Bahrain Financial Harbour - Nakheel Tower (1000m), Dubai - CCTV Headquarters and TVCC Building, Beijing, 2008, Rem Koolhaas and Ole Scheeren