How one design flaw almost toppled a skyscraper - Alex Gendler

譯者: Lilian Chiu 審譯者: Amanda Zhu

In 1978, Diane Hartley was writing her undergraduate architecture thesis

1978 年，

戴安哈特利在撰寫 她的大學建築論文時，

when she made a shocking discovery.

有一個驚人的發現。

Her paper focused on the Citicorp Center, a skyscraper in midtown Manhattan.

她的論文是關於花旗集團中心大樓，

曼哈頓市中心區的一棟摩天大樓。

And after weeks poring over the building’s plans,

花了數週時間鑽研 該建築的計畫之後，

she’d stumbled on a potentially deadly mistake.

她偶然發現一個可能會致命的錯誤。

An oversight that threatened to topple the 59-story tower

這個疏失可能會造成 這棟 59 層的高塔

into one of New York City’s most densely populated districts.

倒塌在紐約市人口最密集的區域之一。

When it was built two years earlier,

兩年前，花旗集團中心建造完成時，

Citicorp Center was one of the world's tallest buildings.

它是世界上最高的大樓之一。

Its sloped roof was unique in the city skyline,

它的傾斜屋頂在天空中形成了 獨一無二的輪廓，

but its more distinctive feature lay at the base.

但它更特別的特色是在它的基底。

Since the construction site was already occupied by St. Peter's Lutheran Church,

因為建地已經被 聖彼得路德教堂給佔據，

the new skyscraper had to be built on columns supporting it, like stilts.

這棟新的摩天大樓 必須像踩高蹺般蓋在支撐柱上。

Using stilts on a building’s corners wasn’t unheard of,

在大樓下方的四個角落 使用支柱並非前所未見，

but because the church stood at the corner of the block,

但教堂佔據的是角落的位置，

these stilts had to be placed at the center of each side.

所以這些支柱必須要設置在 每一邊的中央。

While this novel design worried some of the building's backers,

雖然這種新穎的設計 讓該大樓的一些出資者感到擔憂，

chief structural engineer William LeMessurier

結構首席工程師威廉萊梅雪

took numerous precautions to ensure the building’s stability.

採取了許多預防措施 來確保該大樓的穩定度。

The outside would consist of v-shaped chevrons,

他在外部採用 V 字鋸齒形雕飾，

forming a strong exoskeleton to support the skyscraper.

形成堅固的外骨骼， 來支撐這棟摩天大樓。

This external structure also made the building much lighter,

這種外部結構也讓該大樓 變得更輕許多，

meaning there’d be less weight to support overall.

也就是說支撐的總體重量比較輕。

This design did leave the building vulnerable to strong winds.

這種設計的確會讓大樓 很容易受到強風影響。

But LeMessurier had another state-of-the-art solution—

但萊梅雪還有另一個 先進的解決方案——

a tuned mass damper.

調諧質量阻尼器。

This 400-ton counterweight was controlled by computerized sensors

這個 400 公噸的平衡秤錘

是透過電腦化的感測器來控制。

designed to counteract any swaying.

設計目的是要抵消任何晃動。

With these structures in place,

適當加上了這些結構，

calculations showed that each side of the building could withstand powerful winds.

計算結果顯示，大樓的每一側 都能承受強大的風力。

And with all safety issues resolved, the building opened for business in 1977.

隨著所有的安全問題獲得解決，

該大樓於 1977 年啟用。

But when Hartley was studying the tower a year later, she noticed something odd.

但一年後當哈特利在研究 這座高樓時，

卻覺得有點古怪。

It was true that each face of the building could endure powerful winds.

的確，大樓的每一面 都能夠承受強大的風力。

And since a building’s broad sides catch the most wind,

而且，因為大樓寬廣的面 要承受大部分的風力，

these would typically be the strongest winds a building encounters.

一般來說，這就是大樓 會遇到的最強風力。

However, the towers unique base meant that winds

然而，這高樓的獨特基底意味著

blowing on the building’s corners were actually the bigger threat.

大樓的角落所要承受的風吹 反而是更大的威脅。

And since traditional designs didn't warrant safety calculations

因為傳統設計並不需要 針對角落的風力做安全計算，

for corner winds,

it seemed to Hartley that the threat had gone unaccounted for.

哈特利認為，這項威脅 並沒有被考慮到。

When Hartley contacted LeMessurier’s firm about the issue

哈特利聯絡萊梅雪的公司， 反應這個議題，

they assured her the building was strong enough to handle these winds.

他們向她保證，這棟大樓夠堅固， 可以禁得起這些風力。

But checking the plans again, LeMessurier noticed an alarming detail.

但萊梅雪再次檢查設計圖之後， 注意到了一個令人擔憂的細節。

A change approved without his knowledge

在他不知情的情況下， 有一項變更被核准，

had replaced the exoskeleton’s welded joints

將外骨骼的焊接式接頭

with cheaper and weaker bolted joints.

被換成比較便宜、 不牢固的螺栓式接頭。

This alone wasn’t enough to topple the tower thanks to the mass damper.

幸好有質量阻尼器，光是這個問題 還不至於讓這棟高樓倒塌。

But if a storm knocked out the building's power,

但如果暴風雨造成大樓停電，

it would deactivate the counterweight’s sensors,

秤錘的感測器就會停止運作，

leaving the building vulnerable to winds of just 112 kilometers per hour.

導致大樓無法承受 時速僅 112 公里的風力。

Given available weather data,

根據可得的氣象資料，

a storm this strong had a one-in-sixteen chance

這麼強的暴風雨

of hitting New York City every single year.

每年會有六分之一的機會 襲擊紐約市。

LeMessurier never told Hartley what she’d uncovered.

萊梅雪始終沒有告訴 哈特利她促成了這項發現。

In fact, everything he did next was top secret.

事實上，他接下來 所做的一切都是最高機密。

After filling in the architects and executives at Citicorp,

萊梅雪讓建築師以及花旗集團的 主管了解狀況之後，

LeMessurier’s team worked with city officials to craft a confidential plan.

他的團隊便和該市府官員合作， 訂定了一個機密計畫。

Without warning the residents,

在住戶沒有得到警告的情況下，

construction crews began a string of night-time shifts

建設小組成員便展開一連串夜班，

to reinforce the bolted joints.

任務是強化螺栓式結構接點。

This delicate work began in mid-August 1978,

這個棘手的工作任務 始於 1978 年 8 月中，

and was only halfway complete when Hurricane Ella

九月，颶風埃拉接近紐約市時，

approached the city in September.

才完成了一半。

City officials and Citicorp executives planned an emergency evacuation

該市官員及花旗主管 規劃了緊急撤離計畫，

for a 10-block radius,

範圍半徑達十個街區，

but at the last minute, the hurricane veered out to sea.

但在最後一刻，颶風轉向進入大海。

These secret evacuation plans were never used,

這些秘密撤離計畫始終沒有執行，

and the reinforcements were completed just a month later.

一個月後，強化工作完成。

Typically, it would’ve been impossible for this covert construction to go unnoticed.

通常，這種暗地裡的建造工程 不可能不被注意到。

But the press was occupied with a newspaper strike

但報紙罷工讓媒體忙不過來，

spanning the length of the reinforcement project.

罷工的時間剛好涵蓋了 強化工作計畫的時間。

In fact, the public didn't learn how close they'd come to disaster until 1995,

事實上，直到 1995 年， 大眾一直不知道

他們曾經離災難這麼近，

when a New Yorker article revealed the story to the city, and to Diane Hartley.

《紐約客》的一篇文章向紐約市

以及戴安哈特利揭露了這件事。

Like LeMessurier, the article failed to give credit where it was due,

這篇文章也和萊梅雪一樣， 沒有把功勞歸給應得的人，

but at least Hartley knew that her homework had saved lives.

但至少，哈特利知道， 她的家庭作業拯救了人命。