Name: 摩天大樓屹立不搖的秘密 (The design tricks that keep skyscrapers from swaying)
Uploaded: 2019-03-21T21:01:20.000Z
Duration: 4 min 15 s

This is a hole on top of the Shanghai World Financial Center.

這是一個位在上海環球金融中心上方的洞。

This is a 660-ton steel ball hanging inside of Taipei 101.

這是一個垂吊在台北 101 中，重達 660 公噸的鋼鐵球。

And these are massive clockwise balconies on the Burj Khalifa, the tallest building ever made.

而這些是世界上最高的建築物，哈里發塔上順時針方向旋轉的巨型陽台。

These design choices might seem like gimmicks to give these skyscrapers their iconic looks.

這些設計上的選擇看來好像是為這些摩天大樓賦予代表性外觀的秘密裝置。

But behind each feature is a brilliant engineering trick designed to one thing: Confuse the wind.

但在每一個特色建築的背後隱藏著一個絕妙的工程技術，導引向一個共同目標：搗亂風。

Wind can cause a bunch of issues for buildings: broken windows, structural damage, and discomfort for the people inside.

風可以導致一連串不利於建築物的問題：破裂的窗戶、結構上的損壞和造成建築物中人們的不適。

And today's super-skinny skyscrapers have to deal with a particular wind-induced phenomenon called vortex shedding.

而今天超級細的摩天大樓必須面對一種特別由風引起的現象，叫做旋渦流。

This happens when wind flowing past a building creates vortices, strong swirls of air that magnify the damaging effects of wind.

旋渦流發生於風經過建築物時，產生一種放大風對建築物產生破壞效果的強烈氣流。

In low winds, these vortices cancel each other out.

在低層的風中，這些氣流互相抵消。

But in higher winds, they create alternating low pressure zones that make the building rock back and forth.

但在高層風中，他們創造出交替出現使建築物前後震盪的的低氣壓區。

As the wind speed increases, so does the intensity of the back and forth movement.

隨著風速增加，前後震盪的強度也隨之增加。

Every object also has its own natural sway frequency and when that matches with the frequency of vortex shedding, it creates a dramatic spike in the intensity of swaying.

每一個物體也有自己本身的搖擺頻率，而當這搖擺頻率和旋渦流的頻率一致時，它導致搖擺程度呈現劇烈高峰。

On the top floors of a high rise, that kind of swaying can be nauseating, plus it can damage the integrity of the building.

在一棟高聳建築物的地板上，那樣的擺動令人噁心，再加上它可能會損害建築物的完整性。

But architects have an arsenal of tricks to reduce movement.

但建築師們有許多減少震盪的技巧。

The higher up you build, the stronger the wind force gets.

So to reduce surface area where the wind is stronger, designers can simply make a building skinnier as it gets taller.

所以為了減少高空風速增強區的建築物表面積，設計師們可以純粹地將一棟建築物設計成越高越細的形狀。

They can do that with tapering, like The Shard in London or with periodic setbacks, like the Willis Tower in Chicago.

他們可以用這樣的方式減少風阻，像是倫敦的碎片大廈，或者像是芝加哥定期逐層收進外牆的威利斯大廈。

然後，設計師們可以柔化邊緣。

Hard edges aren't good on wind, so you'll often see skyscrapers with round corners.

堅硬的邊緣對風並不有利，所以你將常常看到摩天大樓有著圓滑的稜角。

But architects can achieve a similar effect with small cutouts from the edges.

然而建築師們也可以藉著削減邊緣稜角的方式達到相似的效果。

The building was originally designed with square corners, but when a scale model was tested in a wind tunnel, the designers saw a lot of swaying.

這棟建築原是設計成有方形的稜角，但當一個比例模型在風道中測試時，設計師們發現很多搖擺的情形。

Here are the results after designers added sawtooth corners.

這裡是設計師們增加鋸齒稜角後的結果。

他們降低了搖擺的程度達百分之二十五。

The next option is pretty simple. You can just open it up with holes.

下一個選項非常簡單。你可以把它穿洞就好。

Skyscrapers like Saudi Arabia's Kingdom Centre and Shanghai's World Financial Center do this with a single gap up top, allowing wind to pass right through where it's blowing the strongest.

摩天大樓如沙烏地阿拉伯的王國中心和上海的環球金融中心採用這樣的方式，在高處開了一個缺口，讓風可以在它吹拂最強烈的地方通過。

But 432 Park Avenue in New York achieves this effect with several double-floor cutouts that allow wind to pass through along the length of the entire tower.

但位在紐約的公園大道 432 號用幾個雙層樓內縮的方式達成讓風通過整棟建築物的效果。

This wind resistance technique makes for some of the most stunning skylines today.

這個阻擋風的技巧創造出一些至今最驚人的摩天大樓。

Dramatic spirals redirect the wind, guiding it upward and off of the building.

劇烈的螺旋狀重新導引風，將之導向上方並遠離建築物。

That's the same wind resistance trick used by some industrial chimneys and car antennas.

那和一些工業用煙囪及車子的天線運用的擋風技巧是一樣的。

Corkscrew shapes like this were impossible to build until fairly recently, thanks to advancements in software and material science.

幸虧有軟體及科技的進步，像這樣的螺旋狀建築物直到現在才有可能被建造。

And they're also promising from a sustainability perspective.

而它們從永續發展的角度來看也十分地有前景。

During the design process on the Shanghai Tower, for example, adding the iconic twist reduced the wind load by 24 percent, saving developers $58 million in structural material.

舉在設計上海中心大廈的過程為例，增加這具代表性的扭轉元素降低風量達百分之二十四，為開發者節省了五千八百萬的建築材料費。

Finally, there's the technique so good it's invisible: damping.

最後，是一個很棒的且隱形的技巧：阻尼。

Dampers are mechanisms designed to absorb the energy from a building's movement, counteracting the effect of the wind.

阻尼器是一種設計來吸收建築物震盪所產生的能量的機械裝置，以抵銷風的效應。

摩天大樓用兩種主要的方式達成這個目標。

First are slosh tanks: these are containers filled with several tons of water.

第一個是泥濘槽：這是充滿好幾噸重的水的容器。

The water sloshes back and forth, and its weight displacement helps keep the building from swaying.

裡面的水前後攪動，而它重量的移位幫忙維持建築物穩定而不會搖晃。

Second are tuned mass dampers: massive weights suspended in the middle of a building.

第二個是調整用的巨型阻尼器：懸吊在建築物中央的很重的重量。

These were traditionally hidden away in building design, placed on empty floors along with other technical equipment.

這些傳統上都隱藏在建築物的設計中，和其他的技術性儀器一起被置放在空樓層中。

But they don't have to be. Taipei 101's tuned mass damper has been a popular tourist attraction since it opened in 2004.

然而它們其實不需要如此。台北 101 的調節巨型阻尼器從它 2004 年開幕至今一直是個熱門的觀光景點。

They even have a mascot for it: Damper Baby.

他們甚至有自己的一個吉祥物：紅金寶。

These shapes, holes, and counterweights form a secret design language hidden inside of our skylines.

這些形狀、洞和秤錘形成一個藏在我們的天際線背後的祕密設計語言。

And as more people move out of rural areas and into urban ones, skyscrapers will keep getting taller and skinnier.

而隨著人們遷移出鄉下地區並遷入都市，摩天大樓將會越來越高，越來越細。

These technologies are what's making that future possible and letting us keep building into the sky.

這些科技正是讓我們實踐這樣的未來的立基，並讓我們繼續建造高聳入雲的建築物。

Thank you so much for watching, if you haven't already heard we've launched a membership program with YouTube called the Vox Video Lab.

非常謝謝你的收看，如果你還不知道我們和 YouTube 一起推動了一個叫 Vox Video Lab 的會員節目。

It's the best way to support our work and interact with us more, and get access to exclusive content.

這是支持我們、和我們有更多互動，並取得獨家內容最好的方式。

To become a member, head over to vox.com/join.

要成為一位會員，快去 vox.com/join。