How and when is it that the skyscrapers were born?

Steel spawned the skyscraper.

The use of cheap steel as a construction material was made possible by the inventions of the 1850s and 1860s, but much of the production was absorbed by the railways because the steel tracks lasted much longer than the iron ones; For other purposes, wrought iron was often preferred because it is more homogeneous and more ordinary. Until 1887, the British Board of Commerce did not authorize the use of steel in the construction of bridges; However, the procedures generated by the German Bessemer and Siemens allowed to have large ingots that could be rolled into the desired shape: the beam in double T, with a very resistant profile. Between 1882 and 1889, 50,000 tons of steel were used in the construction of the Forth Bridge, which firmly established the start of the manufacture and sale of rolled steel beams in England by Dorman Long and other firms.

Meanwhile, the United States had not only already taken the lead in the production of cheap steel, but developed its use for a new type of building, with which steel generated the skyscraper. The main incentive for this was the rapid increase in land value in the congested central areas of booming cities, such as New York and Chicago.

The way for the rise of the skyscrapers had been paved by the fashion of the house with elevator, emerged after EG Otis eliminated - in 1854 - the dangers involved in the hydraulic lift for people, by providing the cab with ratchets, the which were attached to springs with notches on the sides of the elevator shaft at the moment when the cable broke, thus preventing its abrupt collapse and, of course, the certain death of its occupants. Neither these first buildings, nor the even higher ones that would follow them, would have attracted a sufficient clientele of tireless stair climbers but for the elevator.

At the beginning, the new type of structure had wrought iron floors and facades of cast iron -whose different parts were prefabricated-, but they were loaded on masonry walls that required an increase in the thickness of the base, in proportion to the height. In this way they could rise up to fourteen stories, as in the case of the building built by Pulitzer for the New York World in 1890, whose ground floor - where space was most valued - had walls of almost three meters thick. In contrast, a completely steel structure had no such limitations: steel columns could be erected virtually to any height, seated on a secure base and without any size increase at the base. These columns, joined on each floor by steel beams, supported the entire weight of the building, so that the function of the walls was reduced to providing shelter and isolation.

Although steel beams were used on the upper floors of an iron-built office building built in Chicago in 1884, the first complete steel structure was erected in 1890, also in Chicago, followed by the Masonic temple of the same city-twenty-one stories, built in 1892 and described as the largest building in the world, one of its seven wonders, which marked the beginning of a new era.

The erection of the first skyscraper in New York in 1894 illustrated two major difficulties of this type of building: the foundations had to be excavated up to fifteen meters underground, using drawers that would then be filled with concrete, and the structure had to be braced with pieces of supplementary metal to withstand strong winds. By the end of the nineteenth century, New York had eclipsed Chicago with twenty-nine skyscrapers against sixteen and a maximum height of 118 meters versus the 91.5 meters of maximum height achieved in Chicago. Meanwhile, the cities of Europe did not have such silhouettes: during the 1890s, England applied steel only, and still scarcely, in industrial construction. A West Hartlepool warehouse, built in 1896, is the first English example of a complete steel structure, but it was more than another decade before the London Building Law recognized that the thickness of the exterior walls could be safely reduced. If possible, insert them in parts in a structure that supports the entire load.