Summer School URBAN STEEL STRUCTURES July 11 – 15, 2005 Gdańsk, Poland TALL BUILDINGS – PAST, PRESENT AND FUTURE DEVELOPMENTS R. KOWALCZYK University of Beira Interior, Covilha, Portugal 1. Introduction Tall building, as an element of urban environment is rapidly gaining the importance. It is more and more the dominant element of the city skyline and often becomes even the symbol of the city. Also the impact of the tall building on the city is enormous. It influences the environment of the whole neighbourhood in many aspects from problems connected with transport till such small aspects as shadows. Therefore planning and design of tall building in city environment is an interdisciplinary problem, which has to be dealt with be a teams of specialists from various specializations. 2. Council on Tall Buildings and Urban Habitat Mission: • The Council on Tall Buildings and Urban Habitat, is an international non-profit organisation, which task is to facilitate professional exchanges among those involved in all aspects of the planning, design, construction and operation of tall buildings and the urban habitat. • The Council's primary goal is to promote better urban environments by maximising the international interaction of professionals, and by making the latest knowledge available to its members and to the public at large in useful form. • The Council has a major concern with the role of tall buildings in the urban environment and their impact thereon. Providing adequate space for life and work involves not only technological factors, but social and cultural aspects as well. • While not an advocate for tall buildings per se, in those situations in which they are appropriate, the Council seeks to encourage the use of the latest knowledge in their implementation. 2.1. Council Authorities: The Steering Group is the "Board" of the Council. An Executive Committee carries out the policy of the Steering Group. Council Headquarters is located at: Illinois Institute of Technology. S.R. Crown Hall, 3360 S. State Street. Chicago, Illinois 60616 USA, www.ctbuh.org, [email protected]. Correspondence: Geri Kerry, Council on Tall Buildings and Urban Habitat, PO Box 4363Bethlehem, PA. USA 18018 email [email protected]. –7– Chairman Ron Klemencic, Skilling Ward Magnusson Barkshire, Seatle, USA. Executive Director Director Emeritus David M. Maola Lynn S. Beedle Vice Chairmen: • Africa: Syd Parsons • Australia: Henry J. Cowan Ph.D • Europa: Ryszard Kowalczyk, Ph.D • Middle East: Sabah Al Rayes Ph.D • North America: Joseph P. Colaco, Ph.D • Northern Asia: Prof. Fu-Dong Dai • South America: Edison Musa • Southern Asia: Kenneth Yeang, Ph.D • Vice Chairman at Large: M. Ridzuan Salleh Ph.D 2.2. Need: • the growing world population, generally urban, creating increase • demand for tall buildings in areas experiencing urban growth • the consequent requirement for economy in construction • the frequent neglected of human factors in urban design at the • expense of livability and the quality of life • the need to revitalize urban areas experiencing decline through • poverty or crime • the new research required in the field and the necessity of • establishing priorities 2.3. Activities: • Publications • Conferences and Congresses • Database and Information Resources • Identification and Implementation of needed research 3. Tall building - definition Perhaps the first question, which should be answered, is the definition, what is considered to be a tall building. Council on Tall Buildings and Urban Habitat dives following definition of tall building: “A tall building is not defined by its height or number of stories. The important criterion is whether or not some aspects of “tallness” influence the design. It is a building in which tallness strongly influences planning, design, construction and use. It is a building, whose height creates conditions different from those that exist in “common” buildings of a certain region and period. Lest me explain this in a manner Dr Beedle, the founder of the Council and my friend has explained this. If the fire brigade comes to extinguish a fire in a building and its equipment is not sufficient to reach some floors it means that for the fire brigade this –8– building is considered tall. If in a town where there are only buildings let say two three floors high suddenly a building is built with twelve stories and it looks tall therefore it is considered as a tall. The definition is therefore relative, and depends from the aspects taken into consideration. Talking about Civil Engineering aspects the building can be considered as tall when the structural systems depend on tallness, that commonly means that horizontal forces decide on structural system of the building. • Tallness makes that many problems, which can be disregarded in “common buildings” in tall buildings appear as very important ones which must be solved to achieve a proper solution. • Thornton [ “How Tall” Engineering News Record 1983]: “I think everybody has the question do we really want 200-story buildings? I’m not sure we do. I’m sure that engineers and architects could produce one and the construction industry in the US could produce it with no problem. But the interesting thing about working on 200-story building or long span structures is that you learn a lot about exaggerated magnitudes of behavior. When you are working on 20, 30 or 40-story building, there have been 100 of these built before. When you start talking about 200, 400, 500 - story buildings, everything gets exaggerated - differential column shortening, drift, acceleration, dynamic behavior and as we study them in a tall building, we wonder, why we didn’t think about them on a shorter building”. • Present tall building is a result of close co-operation of a team of specialists of various areas and only, if this co-operation is close from the very beginning a successful solution is possible. • Structural system and vertical transportation were usually the main factors limiting the height of a building • Taking into account present developments in technology, these two factors constitute no real limitation to the height nowadays. Fig. 1. One Mile Dream 4. Tall building and its role and function –9– Although tall buildings are generally considered to be a product of the modern industrialized world, inherent human desire to build skyward is nearly as old as human civilization. It is recorded in the Bible in the story of the Tower of Babel “and they said: go to, let us built a city and a tower whose top may reach onto heaven”. The builders thought, that they could reach heaven with their construction and their audacity was punished by God. This tale expresses clearly one of human aspirations: to reach heaven by the extreme height of the structures, to reach sky and go far above our earthly realm to a place that is higher, purer, with not obstructed view around. The Egyptians started to built pyramids some 5000 years ago, and ziggurats in Mesopotamia are almost as old. Also Mayan pyramids, Egyptians obelisks, Chinese pagodas and Moslem minarets thought are not as tall but they create an vertical element so much taller than anything around, a vertical marker against the horizon. Steeples of churches in the Christian tradition, campaniles have played a similar role. This is another attribute of very tall structures that they are place markers. Very tall structures do not only mark a place, but they often become the symbol of a place as for instance Eiffel Tower in Paris. In the 20th century office buildings have become the dominant, tall objects in our cities, representing often private wealthy corporations or individuals. Perhaps it is difficult to accept the fact that those buildings have replaced traditional sacred or civic structures as the symbols for new cities. The earliest skyscrapers were received by public with great enthusiasm. Now in several places they have become too many, often some of them being insensitive to their cities and environment or less than beautiful and they provoked a well justified negative reaction. But in many places they continue to be built with great enthusiasm, most notably in eastern Asia. They continue to be a great architectural and structural undertaking which appears simple at the surface, but is surprisingly difficult to be solved well. The Council book “Architectural Design of Tall Buildings” [1] says following: “Tall building should respond to the two primary criteria: first to the smaller circle of its affected users and second to the larger urban environment. In regard to the first criterion, the building itself must be ganged relative to its purpose, how its lives up to its expectations. The second criterion must be evaluated in its functions an element in the immediate urban setting. The degree to which tall buildings add or detract from the quality of their surroundings is dramatic, affecting not only the immediate users but, because of their size and scale the context of the entire city now and in the future”. Ceasar Pelli the famous architect and designer of several tall buildings in his paper “Cosmic Pillars” [2] makes following important comment: “A new skyscraper is a member of an important class of buildings with well defined characteristics. It belongs also to the place where it is built. It needs to respond in a creative and responsible manner to the climate, surrounding buildings, architectural tradition and to the character, history and ideas of the city and its people. Only than it will be noble and worthy of respect and affection”. These are general principles which have to be taken into consideration whenever a tall building is planned for the city. Unfortunately not always was so. 5. Large Cities Around the World and Tall Buildings –10– Stating that the tall building is a significant element of the urban environment lets us look at the different parts of the world and evaluate the tendencies for tall buildings.