G4 – The Hidden Secret to Skyscrapers On grade -02
New York City is known for its magnificent skyline, the outline of land and buildings we can see from a distance. Few cities in the world can compete with its splendor and proportions. While some cities may have a single building as tall as one of the taller buildings in New York City, they don’t come close to the sheer quantity of tall buildings per square mile.
What makes New York special is this very number of super-tall buildings. Land in New York is highly sought after, making it extremely expensive. To make up for the astronomical prices of a small parcel of land, owners look skyward. When you buy land, you also own the area above it. Therefore, in New York City, it makes sense to build as tall a building as possible. This solution works to a certain point. The problem with constructing a towering building is that they are extremely expensive. With every foot of height, the expense of construction increases dramatically. Fortunately, New York City is the financial capital of the world. If there was ever an ideal place to build super-tall buildings, it would be New York.
Building a super-tall building, or skyscraper as they are known, is an engineering challenge. The buildings themselves are extremely heavy. Tall buildings must be built in an area that is able to support their tremendous weight. Imagine what might happen if you put too much weight in a boat. Of course, the boat would sink. So how is this example related to tall buildings you might wonder? As it turns out, it has everything to do with it. The geology, or types of rocks and soil, in an area is critical knowledge that is needed before a skyscraper can be built.
History has taught us that buildings built on soft soils will subside or sink. Perhaps the best example of subsidence is Italy’s Leaning Tower of Pisa. During construction, the builders noticed that one side of the structure was subsiding. This motion caused the tower to lean to one side. The builders made adjustments as they continued to build upwards hoping to adjust for the displacement. Unfortunately, as the tower gained in height, the tower leaned even more. It was learned many years later that half of the tower was built on marshy, or squishy, soil. If the builders had known this, they could have adjusted their construction techniques. Perhaps an even better idea would have been to build structure in a different location.
As far as modern structures go, the Leaning Tower of Pisa is no competition for today’s giant megaliths or large structures. Engineers would not dare take a chance of building on such a soft soil. Instead, the tallest of buildings are built on bedrock. Bedrock is the first layer of rock strata or layer of continuous rock. Bedrock is located just below the soil. Even then, not all rocks in bedrock are created equal.
