Today we will break the glass. What could be interesting here? And the fact that this is the front glass of the tower of Lakhta Center, which we compared in one of the previous
posts with a stone wall. Intriguing? Then - I ask for me!
WHY GLASS COMPARED WITH STONE?
Let me remind you the background.
The role of the facade in the Lakhta Center tower is played by glass - cold-formed, multi-layered, heat-strengthened. Sheet thickness - 41 mm. The material can withstand a distributed load of 400 kgf / m2 - comparable to the regulatory loads on reinforced concrete floor slabs in the houses of some standard series.
One of the first double-glazed windows of the facade of the Lakhta Center tower arrived at the siteBut glass has a weak point: fragility. The fair question is how does it stand up to shock loads?
Anti-brittleness
Of course, when creating a glass formula for such specific purposes, such loads are taken into account, and then checked by field tests. So we decided to conduct our experiment - not very scientific, but indicative. Let's give a good fight to our glass!
Of course, no one will give attack items with installed objects on the tower on the tower, even for near-scientific purposes. Unincorporated it somehow.
Let's go to the manufacturer's factory - he has samples of glass sheets, completely identical to those that went to the facades of the tower. The blessing is not far: Gartner has localized production, having opened a plant in St. Petersburg.
ROUND FIRST. DISHONEST
All is ready. The glass on the stand you already know. In the opposite corner of the ring - our tester, armed with improvised economic tools and a support group. It's time to make a bet. Go! For a start - simple. We hit the glass with a run.
Something like that...In order not to put our tester out of action, his role will be played by a bag of sand weighing 70 kg - comparable to the average person.
Run
There is not enough data to calculate the impact force, but it is clear - an ordinary person can do the same: the glass cannot be broken.
BELIEVE ME, I AM ENGINEER
In the series "1000 ways to die" in one of the episodes told the real case.
TD Center. It was here ...In 1993, at the Canadian TD Center, lawyer Harry Howe showed students who came on a tour the strength of glass on the facade of a high-rise building — he beat up a run-up about him. Before becoming a lawyer, Hou received a degree in engineering. Moreover, he repeatedly conducted a similar demonstration earlier. But this time he was unlucky: he fell out of the window of the 24th floor. The authorities claim that the glass was not broken by Hou’s blow: it just flew out of the frame, possibly slack due to earlier demonstrations.
Glasses in skyscrapers - not only in Lakhta Center - are really very durable: a person cannot afford to break up his run, using only the mass of his body. But fate should not be tempted.
In Lakhta Center, obligatory quality control passes all components of facade elements — sealants, weld seams, fasteners and anchors, and embedded parts — like elements are selectively checked for “tearing”, “cut”, etc. Results are recorded in test reports. Sometimes the weak link may not be glass, but metal, even though you don’t expect from it.
The glass facade is not only glass but also many other components.
But back to the stand. The first round with the use of "doubler" - in favor of glass, which was predictable. We take the matter seriously.
ROUND 2. SPORTS
We try to break the glass with a wooden baseball bat.
Ten good strikes. The glass was damaged - a tiny chip, but knocked the tool out of the hands of an opponent.
"Damage"Take the "bat" more powerful ...
Go to the ram!
So far - 2: 0, but our fight - to victory.
ROUND 3. UNEXPECTED
An ax for a fire shield with a steel butt and a blade - in a couple of blows it will cut both a baseball bat and a battering ram from the previous test. Steel or glass?
A bent steel blade cost the subject a pair of scratches.
Still - Die HardAnticipating the issues, we emphasize that the fire departments of the hatchet are made according to other standards - with a non-combustible handle, a reinforced butt, a blade of high strength steel, which is facilitated by special additives. The tool that we had during the experiment is a simplified version that is used in emergency situations in order to quickly open doors, windows, etc. And yet - in the hands of our "bully" was quite a good ax, which could not stand the collision with the allegedly fragile material.
ROUND 4. INDICATIVE
The hammer ... no chance?
Here is the most significant moment.
It was not possible to break the glass even with the help of a hammer, although he got it thoroughly. The sheet is damaged and deformed, but it was not possible to achieve either a through hole or shedding.
The matter of technology is triplex - a special film between layers of glass keeps it from shedding. Due to the fact that the glass is hardened, small fragments are formed without sharp edges. In this form, the glass unit can stand up to its replacement by the installers serving the facade.
No, not so) If necessary, two installers will make a replacement: on a special platform moving along the rails in the edges of the tower, they will drive up to the required section already with a new glass package and do their job.
Such convenient platforms are part of the facade service system and we will tell about it.
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Fragility is one of the basic characteristics of glass, so far there are no components that could make it non-fragile without completely changing the material itself. But solutions were invented that make the facade reliable and safe even in case of damage - as we see in our example.
Probably, other, much more sophisticated technologies are just around the corner. Recently, Japanese scientists have created a glass that grows together with damage - small cracks - right before our eyes, in just a few minutes.
DISTRIBUTED LOAD
The end point of our experiments has been reached, but it is difficult to dwell on this. Here are a couple more experiments in conclusion - this time for a distributed load.
And - the final photo, the whole team of testers, on the glass:
VIDEO ON THEME
The plot with the test glass:
The plot about the facades of Lakhta Center:
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The glass for you was beaten by the staff of Josef Gartner GmbH
We thank the company for the help in the organization of tests!
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Every day there are many beautiful photos and key news about the project - in the telegraph Lakhta Center:
t.me/lakhtacenter