Concrete High-rise Buildings  A major advantage of concrete construction for high-rise buildings is the material's inherent properties of heaviness and mass, which create lateral stiffness, or resistance to horizontal movement. Occupants of concrete towers are less able to perceive building motion than occupants of comparable tall buildings with non-concrete structural systems. As a result, concrete has become the material of choice for many tall, slim towers, including many squeezed into narrow building lots in New York City in recent years. Engineers deemed concrete to be the only viable structural option for the structures—including City Spire on West 56th Street, with its slenderness ratio of 10 to 1—to withstand anticipated wind loading.
Continued improvement in concrete strength in the past decade has been a major factor in the development of taller buildings in the United States and throughout the world. New structural systems—including high-strength concrete—created either from concrete alone or with a composite system that includes both concrete and structural steel are partly responsible. These systems enable skyscrapers to resist the enormous wind and earthquake loads imposed along their height and allow these structures to support the vertical loads created by gravity, the weight of the building, and its occupants.
In the last few years the public has been quick to appreciate the concept and advantages of quality, high-rise residential buildings in the inner city. For many designers and contractors, pre-cast concrete is the obvious choice for cladding; it has solidity and strength, factors that recall traditional residential enclosure, yet it has all the advantages of a modern prefabricated product.
Pre-cast cladding panels can be shaped to form mullions and spandrels or storey-height panels and windows. Other components can also be pre-fitted at the pre-cast factory.
What gives pre-cast the edge over other cladding materials for high-rise buildings is its buildability. Some of its advantages are as follows:
- Prefabrication accelerates the construction program and provides an early weather tight enclosure
- On-site 'wet trades' virtually eliminated
- Site installation by a single team of skilled workers, no scaffolding required
- Glazing, fixings, thermal insulation and vapor control incorporated in the factory
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