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This problem falls under the category of aeroelastic vibration. When the bridge deck is blown by a certain flow rate, it will produce self-excited vibration. This is how the Tacama Bridge in the United States was blown over.
Another reason is that a certain bridge pier is loosened due to the vortex vibration of the fluid, and the periodic vibration of the bridge pier causes the bridge deck to produce low-frequency oscillation. The probability of axle coupling vibrations is small because the excitation frequency of the vehicle is much higher.
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The first consideration is that the bridge is not a rigid body and has natural vibration, when the vehicle passes through the bridge, there is pressure on the bridge, the pressure is the deformation of the bridge, if this force coincides with the vibration of the bridge itself, it will resonate, this problem should be controlled in a safe range to avoid damage to the bridge.
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It's not a serpentine resonance at all, it's the bridge that keeps shaking and trembling, causing the picture and people's vision to be distorted.
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It should be a boring play for Chinese cultivators.
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The phenomenon of resonance occasionally occurs in our daily work and life, and once it is formed, it is very powerful. In fact, when we make investments, if the ** or trading varieties we choose resonate, it will also have great power.
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The first consideration is that the bridge is not a rigid body and has natural vibration, when the vehicle passes through the bridge, there is pressure on the bridge, the pressure is the deformation of the bridge, if this force coincides with the vibration of the bridge itself, it will resonate, this problem should be controlled in a safe range to avoid damage to the bridge.
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Stop talking about resonance, it's not resonance at all! It cannot be explained by what we know now.
Even though the bridge is made of steel, have you ever seen that the steel can be deformed to that extent and then returned to its original shape?
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The results of the study showed that it was the structural slabs in the vertical direction of the bridge that caused the vibration of the bridge. It resists the wind so much that when the wind is blocked, a large amount of air passes over the structural slabs and presses against the bridge deck. As the velocity of the blowing air increases due to the constant inflection of the airflow, the pressure decreases above and below the vertical structural plate (Bernoulli's law).
It doesn't matter if the wind is always blowing directly in front of the board, because the pressure drop above and below cancels each other out. However, if the direction of the wind is constantly changing, the pressure will change constantly. This pressure difference acts on the entire deck and is reinforced by the eddy currents generated behind the vertical structural slabs that block the wind, as a result of which the bridge begins to vibrate.
In a similar situation, the ** line will produce a whistling sound under the action of pressure difference and eddy currents.
In the 60s of the 20th century, after calculations and experiments, it was proved that the fraction of the von 6 1 Carmen was correct. The wind damage accident of the Tacoma Bridge was caused by the creation of the Carmen vortex when a certain velocity of fluid flowed through the side wall; The alternating release of the Karman vortex street rear vortex will produce alternating lateral forces perpendicular to the flow direction on the object, forcing the bridge to vibrate, and when the emission frequency is coupled with the natural frequency of the bridge structure, resonance will occur, causing damage.
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The first consideration is that the bridge is not a rigid body and has natural vibration, when the vehicle passes through the bridge, there is pressure on the bridge, the pressure is the deformation of the bridge, if this force coincides with the vibration of the bridge itself, it will resonate, this problem should be controlled in a safe range to avoid damage to the bridge.
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Regarding the incident, Anatoly, a well-known Russian bridge expert, said: The bridge resonance phenomenon may occur due to wind fluctuations and load resonance, and there was a strong wind in Volgograd that day. Since the bridge is made entirely of long-plate metal, the metal structure has not been deformed.
In addition, some relevant industry insiders believe that the reason why the bridge has this phenomenon may be affected by **, or the supporting structure of the bridge is washed out by the flood under the bridge, but the real reason remains to be further investigated.
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Once researched, you can build Transformers. Lossless building changes shape.
And whether it could be a problem with the camera. This one is best explained.
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Due to the deformation of the metal inside the bridge body in case of bad weather and storms. Because the temperature in Russia is minus 75-100 degrees Celsius in winter. Steel will soften and melt at very high temperatures, and when the temperature is too low, it will deform and may crack and break.
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The steel plates on both sides of the bridge are like wooden piles in the flow of water, when the wind detaches from the two passes of the bridge in the form of a high-speed vortex, it will produce an alternating lateral force on the bridge body, and it also has a certain frequency, and when the frequency of the bridge itself is close to it, it will resonate, so that the bridge will produce violent shaking.
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Physically, there is a fixed frequency of the bridge, and when the wind blows across the bridge deck, the air on both sides will produce a vortex, and the amplitude will increase to reach the fixed frequency of the bridge, causing the resonance phenomenon.
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The reason why the bridge shakes abnormally is because there is no support in the middle of the bridge, and when the wind blows across the bridge deck, the air on both sides will appear in the middle of the bridge, and the amplitude will become larger, causing violent vibrations.
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In terms of physical principles, there is an inherent frequency in any physical structure. If the frequency of the forced vibration is close to the natural frequency of the physical structure, it will cause resonance, and at the same time, the bridge blown by strong winds will also cause the bridge to shake, and it may cause violent resonance.
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This is due to the influence of the air flow, and it may be that there is something on the bridge blocking the passage of air flow, causing the bridge to lose its balance. It could be that a water barrier, a fence or something like that changed the bridge deck.
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The abnormal jitter of the bridge is due to the air flow, because any physical structure has a fixed frequency, and if the external frequency is reached, it will cause the structure to resonate.
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According to China News Service, many cheerleaders will dance wave dances on the sidelines during sports competitions, and there is a bridge in Volgograd City, south of Moscow, the capital of Russia, which has the ability to do this, and the whole bridge is like a wave that keeps rising and falling, which looks very scary. Russia recently released a video: On the night of the 19th of this month, the bridge deck of the Volgograd River Bridge suddenly rolled in waves, and dozens of vehicles driving on the bridge were in danger, and the bridge and water traffic were quickly closed.
At the time of the incident, the pavement of the bridge suddenly began to squirm, resembling a wavy shape and emitting a deafening sound, and the vehicles that were moving on the bridge were jumping in the roll. From the side, the bridge is rocking one after another, up and down. **After receiving the alarm, quickly close the traffic on both sides of the bridge and close the water access road at the same time.
Experts also rushed to the scene, and bridge experts doubted the stability and safety structure of the bridge. After the vibration of the bridge stopped, experts inspected the roads and fences throughout the bridge and found that the bridge was free of cracks and damage. After an initial inspection, engineers believe that this phenomenon may be affected by **, or the support structure is washed out by flooding, but the real cause remains to be investigated.
Anatoly, a well-known Russian bridge expert, said that this phenomenon can occur due to wind fluctuations and resonance of loads. The bridge on the lower Volga River was completed and opened to traffic on October 10, 2009, and took 12 years to build. The closure of the bridge is now causing considerable inconvenience to local residents, who have to take a ferry instead of having to detour 100 kilometres to another bridge to cross the river.
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Underground creeping, also known as surface creeping. The underground creeps, shaking the foundation of the bridge pier, the bridge pier will shake, driving the bridge deck to shake. The surface creep is smaller than **, the range is small, and the surface layer of vibration is also shallow.
Generally, there is surface creep before **. We often see the phenomenon of creeping in the ground, and sandy soil is more pronounced.
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That's so exaggerated, it feels like a convex lens dangling back and forth, and the cement is not plasticine, how can it be compressed so much at once.
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The most important thing is that there are no cracks later.
Resonance is a condition in which a physical system vibrates at a greater amplitude than other frequencies at a specific frequency. The reason why it is fatal is because there is a process of energy accumulation and release, and each vibration will accumulate positive work, and finally release a huge energy force.
Because these bridges have been scientifically calculated, built with solid materials, and have a very thick foundation, they generally do not collapse.
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