It is predicted that the "fireworks" will make landfall (typhoon level or strong typhoon level, 12-14 level, 33-42 m/ s) in the coastal area from Zhoushan to Sanmen in Zhejiang Province from the afternoon to the night of the 25th, and after landfall, it may continue to go deep into the inland, and may also be pulled back to the sea again.
At present, the "fireworks" are on the southern surface of the East China Sea, about 310 kilometers southeast of Xiangshan County, Zhejiang Province, with an intensity rating of strong typhoon level, the maximum wind near the center is 13 (40 m / s), and it is expected to move in a north-westerly direction at a speed of about 15 kilometers per hour, and gradually approach China.
As we all know, the eastern coastal area is China's economically developed area, the population density is also the largest, there are many high-rise buildings here, especially Shanghai. Shanghai's Lujiazui is home to a multitude of high-rise buildings, and if a typhoon hits Shanghai, how can these high-rise buildings resist the wind?
<h1 class="pgc-h-arrow-right" data-track="4" > Shanghai Tower</h1>
Among the many high-rise buildings in Lujiazui, Shanghai, Shanghai Tower is the tallest, and it is also currently the tallest building in China, with a height of 632 meters, which is the second tallest building in the world, second only to the Burj Khalifa (828 meters) in Dubai, United Arab Emirates. Let's take the Shanghai Center as an example.
Unlike ordinary buildings, high-rise buildings with a height of more than 500 meters are subjected to greater wind speeds, generally 2 to 3 steps larger than the ground. If the wind is fast enough, it is possible to make the whole building shake, which cannot be avoided. Therefore, it is necessary to have a strong wind resistance.
Between June and September of each year, the eastern coastal areas of our country have a certain probability of being hit by typhoons, and Shanghai is located in the entire region. Therefore, Shanghai has a certain probability of being hit by typhoons every year, which puts forward high requirements for the wind resistance of Shanghai buildings.
Not only that, Shanghai is an alluvial plain, to put it bluntly, due to the sediment deposition that the Yangtze River continues to carry into the sea, the western part of Shanghai was gradually formed about 7,000 years ago, while the eastern region began to form slowly before 2,000 years ago. As a result, Shanghai's soil layer is softer than inland. If not handled properly, there is a risk of repeating the mistakes of the Leaning Tower of Pisa.
Engineers first have to build a solid enough foundation, the main method is to put tens of meters long pile directly into the soil layer, and then pour a layer of bottom plate above the pile, and then put a raft on the bottom plate, so that the problem of unstable foundation can be solved.
In order to improve the wind resistance of the Shanghai Tower, when designing the shape, the façade used by the designers was a rounded triangle, which could reduce the wind load by 24%. Not only that, when designing the main mechanism, a huge frame plus a core tube and an outstretched truss are used, which can maximize the wind resistance of shanghai center. At the same time, it adopts the outer curtain wall of the suspension structure, radial strut and horizontal diagonal bracing support system, and at the same time with retractable supports, which can greatly reduce the deformation difference between the main structure of Shanghai Tower and the curtain wall structure, and these designs can effectively reduce the impact of wind on Shanghai Tower.
<h1 class="pgc-h-arrow-right" data-track="11" > damper</h1>
Even if these designs are used, when the wind is very strong, the Shanghai Tower still shakes, and the shaking can even reach a very exaggerated degree, even more than 1 meter lateral swing. It is said that in the case of a typhoon, this lateral swing can reach 1.4 meters. If you just let it go, people in the building will be dizzy. In order to eliminate shaking, a damper is required.
On the 125th floor of the Shanghai Tower, a pendulum eddy-current tuned mass damper was installed, weighing 1,000 tons. This damper is mainly composed of a main structure protection system, a damping system, a sling, and a mass block. Dampers cannot be used directly to block wind, and its principle is to use resonance to eliminate shaking. Specifically, create a reverse swing to hedge against the building's own lateral swing.
If the Shanghai Tower suffers from a typhoon, the damper will begin to work, using mass blocks and slings to create a giant swing, this giant swing will provide the Shanghai Tower with a reverse swing to hedge the lateral swing of the Shanghai Tower itself, in order to enhance the wind resistance of the Shanghai Tower, which makes the Shanghai Tower flat under the strong wind.
<h1 class="pgc-h-arrow-right" data-track="15" > summary</h1>
The reason why the Shanghai Tower can resist typhoons is mainly to optimize the structural design and minimize the wind load, and also use dampers, which can effectively resist typhoons by hedging lateral swings through the reverse swing of the resistance.