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Scientific Principles of Building Skyscrapers

Before modern building techniques, builders used stone blocks to hold up buildings, and beyond 10 stories or more this became too difficult to be practical. However, several technological innovations that occurred in the 19th and 20th centuries have allowed architects to build skyscrapers that tower over cityscapes.

I-Beam
- The innovations in the late 19th century that allowed manufacturers to cheaply mass produce steel led to the creation of I-beams, which are pillars of steel shaped like the letter I. I-beams make up the internal structure or superstructure of skyscrapers. Steel is much stronger and lighter than stone, and so steel I-beams can absorb substantially more force from above. This strength forms the backbone of large skyscrapers.
Grillage
- Grillage absorbs the force of the skyscraper and spreads it across a wide area. Grillage is a set of I-beams laid horizontally and stacked on top of one another. It looks similar to a pyramid and operates on similar building principles, with the multiple I-beams on the bottom supporting the higher I-beams. On the very top of the grillage rests a vertical I-beam that supports the building's superstructure. These grillage systems absorb the force of the tall skyscrapers and allow them to reach as high as they do.
Seismic Dampers
- Large skyscrapers would be very vulnerable to earthquakes because of their relatively thin, tall structures. To keep skyscrapers from collapsing in an earthquake, builders include many seismic dampers within the structure. Base isolation systems are a combination of springs, padding and ball bearings that separate the actual skyscraper from its foundation. This allows the buildings to sway freely in an earthquake. Some skyscrapers also include diagonal I-beams in their superstructure, which help absorb the horizontal forces of seismic activity and direct it upward into the strong, vertical structure of the building.
Curtain Wall
- The curtain wall is the outside wall of the skyscraper. Older buildings that don't contain skyscraper technology use the exterior wall as a load bearing agent, which means they must support the weight of the building. As a result, builders typically used stone, brick or a similarly strong material. Curtain walls on skyscrapers have no load-bearing purpose; instead, they cover the interior of the building like a window curtain. Because of the I-beam structure that supports the building, curtain walls can be made entirely of glass windows, decorative materials or anything the architect desires.

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