The history of engineering revolutions Part 4
No doubt steel is a material very good. But it has several drawbacks. First, the steel rusts; secondly melted. If the frame from the action of temperature begins to soften, and it is at this moment pushing a huge load of overlying floors, it is, of course, a direct path to the accident. There is a third drawback of steel is quite expensive.
So we move on to the next revolution: it is related to the appearance of the material, which saves the steel from all its drawbacks flick of the wrist. This material is reinforced concrete, which combines the best properties of steel and stone (concrete is still artificial stone). So it works out. The lower layers of any horizontal beam is always stretched, the upper compressed. Remember that tensile steel is working well, so we put a big piece of rebar in bottom of beam.
And the stone works well in compression. So, based on the top of the section of the beam we place more concrete. The metal is protected from corrosion and from fire, and its consumption is relatively small.
The first house of high grade reinforced concrete appeared in 1853 in France. Built it, Francois Koine. But it is not patented and did not develop the technology. So many people associate the advent of reinforced concrete in construction with the name of the gardener Joseph Monier. He sold plants in pots, which are often fought. And he figured out how to solve this problem.
He made a pot of steel mesh and plastered it with cement sand mortar. In 1867 the technology he patented. And then he patented and everything else that you can do from reinforced concrete: bridges, floors, staircases and the like. Later, all the patents he had bought the Germans. They laid the foundations of the science of concrete and contributed to its spread throughout the world.
The Germans brought the concrete. We have a history of Gum. Graceful bridges of Gum, the balcony is all made of reinforced concrete.
Finally, one last revolution connected with the advent of new designs in which the concrete was taught to take all sorts of forms, exactly following, firstly, the architect that gave him great tools, and secondly, the intention of the engineer because of concrete because of its pliability might take exactly the forms that was the most rational from the point of view of distribution of loads in this design. Such structures are called surfaces shells. The trendsetter here was the Italian engineer pier Luigi Nervi, who built a lot of shells worldwide.
Sheath is a coating of very small thickness that can be well illustrated by the eggs. The ratio of shell thickness to the diameter of the balls is 1:133. If you mentally increase the egg to the size of the Pantheon, the shell of this egg is 12 times thinner than the dome of the Pantheon, despite the rational design of this building.
That is, in the second century, when the Pantheon was built, nature, significantly ahead of engineering. And now look at built by Nervi in 1958 in the Paris showroom. Just imagine: when the width of the span of 220 meters (commensurate with a football stadium), it is covered with a shell thickness of only 12 inches. And the egg of the same size would have a shell thickness of two meters!
In the 60-70 ies of XX century by the architects once again beginning to turn to steel, and German Frei Otto, one of the first creates a mesh coating of steel and glass. It seems to me that any professional at a certain stage of its growth begins to ask questions like: "Who are we? How and where are we going?" And, apparently, Frei Otto thought, "well, I was the first who came up with similar steel and metal and glass shell?" He began to look for those who have ever dealt with, and I came across the work.
About all forgotten for many years. A little known as the author of hyperboloid towers, but no one remembered his unique mesh cover. And it was the first who in 1894 had the idea to use steel in tension not only in bridges but also in the coating of buildings.
One of latest trends in engineering and designing of coatings of steel shell membrane, the use of which is now firmly entrenched in the jurisprudence of the European, North American and Japanese architecture. Membranes are referred to as coatings, which simultaneously perform the load bearing and enclosing functions. That is, it holds its own weight, and at the same time protects from snow and rain. It's very thin shells that are usually made of synthetic fabric is fairly thick compared to normal tissue, but thin compared to concrete shells.
Membrane also invented, and that is their charm. In a mesh coating carrier has a mesh part and enclosing the part of the roofing iron or glass. Thought, and whether immediately out of roofing iron to make a coating that could withstand the load? As a result, for the same exhibition he built the pavilion rotunda with suspended membrane with a diameter of 25 meters, which was made from corrugated iron and could really carry the load.
The Millennium dome in London, built by Richard Rogerson, created with application of technology of the shell membrane.
What will be the next revolution, I don't know. But it seems to me that a fruitful way, as we saw in the previous revolution, is a way of addressing the past. Study the past and you'll be one step ahead!