© John W. Cahill/CTBUH
© John W. Cahill/CTBUH
Other names the building has commonly been known as, including former names, common informal names, local names, etc.
New York Telephone Building, AT&T Long Distance Building
CTBUH collects data on two major types of tall structures: 'Buildings' and 'Telecommunications / Observation Towers.' A 'Building' is a structure where at least 50% of the height is occupied by usable floor area. A 'Telecommunications / Observation Tower' is a structure where less than 50% of the structure's height is occupied by usable floor area. Only 'Buildings' are eligible for the CTBUH 'Tallest Buildings' lists.
The CTBUH follows the United Nations's definition of Country, and thus uses the lists and codes established by that organization.
The CTBUH follows the United Nations's definition of City, and thus uses the lists and codes established by that organization.
A single-function tall building is defined as one where 85% or more of its usable floor area is dedicated to a single usage. Thus a building with 90% office floor area would be said to be an "office" building, irrespective of other minor functions it may also contain.
A mixed-use tall building contains two or more functions (or uses), where each of the functions occupy a significant proportion of the tower's total space. Support areas such as car parks and mechanical plant space do not constitute mixed-use functions. Functions are denoted on CTBUH "Tallest Building" lists in descending order, e.g., "hotel/office" indicates hotel function above office function.
All-Steel
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from steel. Note that a building of steel construction with a floor system of concrete planks or concrete slab on top of steel beams is still considered an “all-steel” structure as the concrete elements are not acting as the primary structure.
All-Concrete
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from concrete which has been cast in place and utilizes steel reinforcement bars and/or steel reinforced concrete which has been precast as individual components and assembled together on-site.
All-Timber
Both the main vertical/lateral structural elements and the floor spanning systems are constructed from timber. An all-timber structure may include the use of localized non-timber connections between timber elements. Note that a building of timber construction with a floor system of concrete planks or concrete slab on top of timber beams is still considered an “all-timber” structure as the concrete elements are not acting as the primary structure.
Mixed-Structure
Utilizes distinct systems (e.g. all-steel, all-concrete, all-timber), one on top of the other. For example, a Steel Over Concrete indicates an all-steel structural system located on top of an all-concrete structural system, with the opposite true of Concrete Over Steel.
Composite
A combination of materials (e.g. steel, concrete, timber) are used together in the main structural elements. Examples include buildings which utilize: steel columns with a floor system of reinforced concrete beams; a steel frame system with a concrete core; concrete-encased steel columns; concrete-filled steel tubes; etc. Where known, the CTBUH database breaks out the materials used within a composite building’s primary structural elements.
