Not all damage to a supporting structure to fall immediately into the eye. How are civil engineers so that a bridge or a large hall is safe? Many of the clues result in a image.
Damage be found, temporarily, the structural brackets increase – until the bridge is re-built
Concrete structures such as bridges or large halls must be able to withstand all kinds: Always truck heavier thunder across the roads, factories have to carry huge machines. The floors of dance it must rooms able to withstand, if there are hundreds or even thousands of people bounce at the same time rhythmic. And also the weather added to the buildings.
Steel concrete or prestressed concrete is actually quite stable and can bear large loads. But there are certain influences that inform this stability.
Water, acid, rust and loads
In particular, water, if it penetrates into the building structure and the steel reinforcement to rust, which give the concrete its strength. It is even worse if road salt or other aggressive chemicals. Then the reinforcement due to rust much faster.
Acids not only attack the metal, but also of the concrete itself. The lime-containing Compounds of the cement to loosen the concrete wears down and becomes brittle. Even rain water can already cause such a thing, especially if the concrete is rough and the surface is zerklüftetet, which favors the Penetration of water.
Also extreme physical stress, the microstructure of the concrete, crumble, are a great danger. This can be vibrations, a large mass acting on the structure are caused by snow loads on roofs – or recurrent vibrations as you venture through trucks on bridges.
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The visual inspection alone is not enough
In the case of a test engineers look at the building first, from the outside, thoroughly: there Are obvious water stains? Formed under the building drip stones? This would mean that over a long time water has penetrated the concrete and lime has been flushed out. There is spalling of the concrete? The reinforcement parts are visible that are rusted? Covered the surface with algae and mosses?
Then, the engineers need to figure out where the reinforcements are. The old blueprints are – where available – useful. Next, come the magnetic inductive measuring devices are used, similar to the metal detectors, the do-it-yourselfers use to look in the wall for cables and pipes, or even treasure hunters to find coins. The devices can detect metals about ten inches deep in the concrete. Lower steel reinforcement can be localized. There are about radars, which can detect water accumulation.
Samples from the structure
Where the reinforcements are, need to know the engineers, before conducting such a core hole. Because of the hole, the engineers do not want to take the steels. The cores can be in the lab on their break and compressive strength is checked.
The corrosion state of steel reinforcement in a structure can first be used to non-destructively estimate. For this purpose it uses the method of potential field measurement. It is based on the fact that the reinforcing steel behaves similarly to a battery, if it is corroded for example by the ingress of salt water.
One end of the reinforcement iron will of self to the Anode, and the other to the cathode. If the engineers a measuring device on the concrete floor and this surface depart, you can measure a potential field – that is, the voltage emanating from the reinforcement. Where there is a strong anodic Potential is evident, corroded, probably deep in the concrete and the reinforcement. These Bodies have to examine the engineers and then in more detail.
To do this, you can also place reinforcing steels on a trial basis-free and examine or remove it. But this is only if a structural engineer has ensured that the stability of the building is not compromised by the removal. This is about 35 centimeters long pieces come to the lab. There it is determined how much traction yet able to withstand before breaking. So it is possible to determine whether the metal cracks due to small hair is already unstable.
Are the wires ripped already?
Especially in the case of prestressed concrete structures, the reinforcement play a particularly important role. The tension wires to ensure that such a long bridge parts remain at all stable.
To find out whether those wires are broken, use the engineers to a similar procedure, involving the use of, any wire, such as a rod-puller and measure its magnetic field probes, which will lead you to the car through the building. Where a magnetic field ends and a new, different Type is definitely a fraction in the steel.
With the Hammer against the wall
Not only the reinforcement, the concrete is first checked without damaging it. The most common is the measurement of the compressive strength of the concrete using a rebound is a hammer.
It is a with a spring driven bolt, which hits with defined velocity on the surface of the concrete. Then he bounces back, more or less. By the strength of the rebound, how much the energy of the blow of the concrete. That conclusions on the strength of the concrete. The Hammer bounces back very strongly, is the concrete hard and strong. He bounces back is weak, the concrete is porous and may be unstable.
Of the concrete to protect the reinforcement against water and air. This is only possible if he is firm and its surface is fine.
Litmus test: What is the pH of the concrete?
In addition to his physical strength, a good concrete must also be chemically stable so that he protects the hidden reinforcing steel. Concrete comes in contact with water, reacts with the carbon dioxide from the air. It comes to a so-called Carbonization of the concrete.
For the concrete itself, it would be no Problem, because of this even stronger than before. But the rebar suffer: they rust faster. How strong is this Carbonization is progressed, the engineers, by spraying an indicator solution of Phenolphthalein, similar to the litmus pH test strips from the chemistry class. The can do the building controller also, of course, to drill cores in the laboratory.
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Preserve or Demolish: Brutalist architecture around the worldManifest from raw concrete
Brutalist architecture, this means above all: a Lot of raw concrete. Exposed concrete, a French “béton brut”, was the klotzigen architectural style its name. A pioneer of this modernist design by the famous architect Le Corbusier, built the “Cité Radieuse” in Marseille. Here is the basement. Many of the buildings of the gradual decay or demolition threatens today.
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Preserve or Demolish: Brutalist architecture around the worldCentral Documentation Site
The National and University library of Kosovo, by Andrija Mutnjakovic designed, was inaugurated in 1982 in Pristina. You should collect “the documentary and intellectual heritage of Kosovo, preserve and promote”. The building itself is supposed to represent a style, “the Byzantine and Islamic architectural forms together,” says the architect. The photo is part of the exhibition.
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Preserve or Demolish: Brutalist architecture around the worldStrong Contrasts
This 1971-built monument by Miodrag Zivkovic is located in the Sutjeska national Park in Bosnia and Herzegovina. It was built to commemorate the roughly 20,000 partisans, fought in may and June of 1943, against the advancing German troops. The work will be shown in the exhibition “Toward a Concrete Utopia: Architecture in Yugoslavia, 1948-1980,” in the New York MoMA.
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Preserve or Demolish: Brutalist architecture around the worldBrutalism around the globe
In the 1950s to 1970s brutalism flourished around the World, the monumental concrete colossi emerged, and the world was a fight to you. In India, it was Le Corbusier who suggested in 1951 with two distinctive buildings in Chandigarh and Ahmedabad new architectural currents on the subcontinent, and many architects are so inspired.
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Preserve or Demolish: Brutalist architecture around the worldA lot to discover: brutalism in Eastern Europe
In recent years, many complex image volumes have been published to the variety of brutal ballistic architecture in Eastern Europe. For the preservation of the “Thermal Hotel” in the Czech Republic since the 1960s, the “International film festival Karlovy Vary” takes place, the family of the architects of a campaign under the name of “respect mA’am”.
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Preserve or Demolish: Brutalist architecture around the worldHot debates in America and England
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Preserve or Demolish: Brutalist architecture around the worldBrutalist classic, to be demolished
For the preservation of the residential complex “Robin Hood Gardens” in East London, built by the architects Alison and Peter Smithson, was fought over for years. The campaign also joined the 2016 late star architect Zaha Hadid. It was no use. In the late summer of 2017, the excavators moved in and began the demolition.
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Preserve or Demolish: Brutalist architecture around the worldStage wins at the monument protection
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Preserve or Demolish: Brutalist architecture around the worldGerman brutalism in danger
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Preserve or Demolish: Brutalist architecture around the worldSuccessful Conversion
If the money for maintenance and rehabilitation is lacking is fast, the whole construction in danger. The brutalist St. Agnes Church in Berlin was a case in point. In 2011, it was leased by the Berlin gallerist Johann König and rehabilitated. It is preserved in its original architecture and now seat of the gallery of king.
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Preserve or Demolish: Brutalist architecture around the world“El Helicoide” in Caracas
The “Helicoide de la Roca Tarpeya” in Caracas, Venezuela, should be a huge Shopping Center. Due to under-funding and the political conflicts of the construction, in 1960, was stopped. In the 1970s, the building was illegally occupied, later, by the secret service as a service seat. Today it is partly used as a prison for political prisoners. The building is surrounded by Slums.
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Preserve or Demolish: Brutalist architecture around the worldThe brutalism new encounter
The Habitat 67 in Montreal, Canada, belongs to buildings to the most brutally ballistic. Architect Moshe Safdie had designed it for the Expo in 1967, and actually, as a reaction against the brutalism understood. Since 2009, it is under monument protection and is now considered “architecture”.