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On April 7, 1930, a forest of 210 giant steel columns began to sprout. The columns rested on concrete bases, called piers, that were sunk deep into the bedrock. The first level of columns in the foundation hole were the most massive in the building. They had to be - they carried the full weight of the building. Each one stood nearly 16 feet tall and weighed 44 tons. When the building was finished, each column would support 5,000 tons of skyscraper! Hundreds of horizontal steel beams were attached to the columns, joining them together in a three-dimensional grid. The beams didn’t have to be as massive as the columns. They contributed to the strength of the framework, but they didn’t carry as much weight. Concrete was used for the floors because it made a strong, smooth surface. It also protected the beams from fire. This was very important in a skyscraper. Steel could not burn but, without fireproofing, heat from a fire could soften it enough to weaken the framework and endanger the entire building. |