Tube (structure) in the context of Structural load

The Chicago School refers to two architectural styles derived from the architecture of Chicago. In the history of architecture, the first Chicago School was a school of architects active in Chicago in the late 19th, and at the turn of the 20th century. They were among the first to promote the new technologies of steel-frame construction in commercial buildings, and developed a spatial esthetic which co-evolved with, and then came to influence, parallel developments in European Modernism. Much of its early work is also known as Commercial Style.

A "Second Chicago School" with a modernist esthetic emerged in the 1940s through 1970s, which pioneered new building technologies and structural systems, such as the tube-frame structure.

A skyscraper is a tall building with many habitable floors. Most modern sources define skyscrapers as being at least 100 metres (330 ft) or 150 metres (490 ft) in height, though there is no universally accepted definition, other than being very tall high-rise buildings. Skyscrapers may host offices, hotels, residential spaces, and retail spaces. Skyscrapers are a common feature of large cities, often due to a high demand for space and limited availability of land.

One common feature of skyscrapers is having a steel frame that supports curtain walls. These curtain walls either bear on the framework below or are suspended from the framework above, rather than resting on load-bearing walls of conventional construction. Some early skyscrapers have a steel frame that enables the construction of load-bearing walls taller than those made of reinforced concrete. Modern skyscraper walls are not load-bearing, and most skyscrapers are characterized by large surface areas of windows made possible by steel frames and curtain walls. However, skyscrapers can have curtain walls that mimic conventional walls with a small surface area of windows. Modern skyscrapers often have a tubular structure, and are designed to act like a hollow cylinder to resist wind, seismic, and other lateral loads. To appear more slender, allow less wind exposure and transmit more daylight to the ground, many skyscrapers have a design with setbacks, which in some cases is also structurally required.

Contemporary architecture is the architecture of the 21st century. No single style is dominant. Contemporary architects work in several different styles, from postmodernism, high-tech architecture and new references and interpretations of traditional architecture like New Classical architecture to highly conceptual forms and designs, resembling sculpture on an enormous scale. Some of these styles and approaches make use of very advanced technology and modern building materials, such as tube structures which allow construction of buildings that are taller, lighter and stronger than those in the 20th century, while others prioritize the use of natural and ecological materials like stone, wood and lime. One technology that is common to all forms of contemporary architecture is the use of new techniques of computer-aided design, which allow buildings to be designed and modeled on computers in three dimensions, and constructed with more precision and speed.

Contemporary buildings and styles vary greatly. Some feature concrete structures wrapped in glass or aluminium screens, very asymmetric facades, and cantilevered sections which hang over the street. Skyscrapers twist, or break into crystal-like facets. Facades are designed to shimmer or change color at different times of day.

The Willis Tower, formerly and still commonly referred to as the Sears Tower, is a 110-story, 1,451-foot (442.3 m) skyscraper in the Loop community area of Chicago in Illinois, United States. Designed by architect Bruce Graham and engineer Fazlur Rahman Khan of Skidmore, Owings & Merrill (SOM), it opened in 1973 as the world's tallest building, a title that it held for nearly 25 years. It is the third-tallest building in the Western Hemisphere, as well as the 23rd-tallest in the world. Each year, more than 1.7 million people visit the Skydeck, the highest observation deck in the United States, making it one of Chicago's most popular tourist destinations. Due to its height and location, the tower is visible from a great distance. The building has appeared in numerous films and television shows set in Chicago.

The building occupies a site bound by Franklin Street, Jackson Boulevard, Wacker Drive, and Adams Street. Graham and Khan designed the building as nine square "tubes", clustered in a 3×3 matrix; seven of the tubes set back at upper floors. The tower has 108 stories as counted by standard methods, though the building's owners count the main roof as 109 and the mechanical penthouse roof as 110. The facade is made of anodized aluminum and black glass. The base of the building contains a retail complex known as the Catalog. The lower half of the tower was originally occupied by retail company Sears, which had its headquarters there until 1994, while the upper stories were rented out.

Fazlur Rahman Khan (Bengali: ফজলুর রহমান খান, Fazlur Rôhman Khan; 3 April 1929 – 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of tubular designs" for high-rises, Khan was also a pioneer in computer-aided design (CAD). He was the designer of the Sears Tower, since renamed Willis Tower, the tallest building in the world from 1973 until 1998, and the 100-story John Hancock Center.

A partner in the firm Skidmore, Owings & Merrill in Chicago, Khan, more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the 20th century. He has been called the "Einstein of structural engineering" and the "Greatest Structural Engineer of the 20th Century" for his innovative use of structural systems that remain fundamental to modern skyscraper design and construction. In his honor, the Council on Tall Buildings and Urban Habitat established the Fazlur Khan Lifetime Achievement Medal, as one of their CTBUH Skyscraper Awards.

The Plaza on DeWitt is a 407 unit condominium property at 260 E. Chestnut Street in the Streeterville neighborhood of Chicago.

It was the first building in the world to implement the tubular construction, later used for the World Trade Center. Originally called the DeWitt-Chestnut Apartment Building, it was designed by Bangladeshi-American engineer Fazlur Rahman Khan while he was working for Skidmore, Owings & Merrill. It was completed in 1966 as a residential apartment building, and was converted to condominiums in 1975. The 43-story tower accommodates 407 residences and is clad in travertine marble. On the ground floor, French bistro Le Petit Paris serves traditional French cuisine.