在花旗中心于1970年启动之前，这片土地被维多利亚式的圣彼得福音教堂占据，该教会允许花旗集团在不影响现有建筑的情况下建造一座摩天大楼。这意味着整个建筑将需要在教堂上方盘旋，比街道高出9层，大概是把它放在码头上。更重要的是，保存教堂意味着没有任何支撑可以位于地段的角落，从而产生一个设计，将柱移动到每一个剖面的中间。尽管这座教堂在一年之内就被拆除了，但在它曾经矗立的地方，却建起了50层的办公空间，达到了915英尺的高空。花旗中心于1977年竣工，成为世界上第七高楼。

Before the Citigroup Center was started in 1970, the lot was occupied by the Victorian-style St. Peter’s Evangelical Church, which gave permission to Citigroup to build a skyscraper on the condition that it wouldn’t affect the existing structure. This meant that the entire building would need to hover above the church, nine stories above street level, presumably by placing it on piers. More importantly, preserving the church meant that none of the supports could be located at the corners of the lot, resulting in a design that moved the columns to the middle of each profile. Although the church was demolished within the year, fifty stories of office space were erected over the spot where it once stood, reaching a soaring height of 915 feet. Upon its completion in 1977, the Citigroup Center became the seventh tallest building in the world.

Before the Citigroup Center was started in 1970, the lot was occupied by the Victorian-style St. Peter’s Evangelical Church, which gave permission to Citigroup to build a skyscraper on the condition that it wouldn’t affect the existing structure. This meant that the entire building would need to hover above the church, nine stories above street level, presumably by placing it on piers. More importantly, preserving the church meant that none of the supports could be located at the corners of the lot, resulting in a design that moved the columns to the middle of each profile. Although the church was demolished within the year, fifty stories of office space were erected over the spot where it once stood, reaching a soaring height of 915 feet. Upon its completion in 1977, the Citigroup Center became the seventh tallest building in the world.

 © Flickr user Jeff Stvan

c Flickr用户Jeff Stvan

从街道的高度往上看，它靠在高跷上的方式有些令人不安的不稳定。就像一张有着糟糕的腿的桌子，它看起来不稳定，好像太用力地推在建筑物的一个角落会把整件东西打翻。然而，它有一个成功的界面与人行道，创造了一个迷人的悬垂与光滑，灰色的脸，吸引眼球。在悬臂下的细节被深思熟虑地表达，给了一个干净的，超有序的单板，一个罕见的下腹部看到巨大的摩天大楼。

Looking up at the building from street level, there is something unnervingly precarious about the way it rests on its stilts. Like a table with badly positioned legs, it appears unstable, as if pushing too hard on one corner of the building would send the whole thing toppling over. Yet, it has a successful interface with the sidewalk, creating a captivating overhang with a sleek, gridded face that draws the eye. The details under the cantilever are thoughtfully articulated, giving a clean and hyper-ordered veneer to the rarely seen underbelly of a mammoth skyscraper.

Looking up at the building from street level, there is something unnervingly precarious about the way it rests on its stilts. Like a table with badly positioned legs, it appears unstable, as if pushing too hard on one corner of the building would send the whole thing toppling over. Yet, it has a successful interface with the sidewalk, creating a captivating overhang with a sleek, gridded face that draws the eye. The details under the cantilever are thoughtfully articulated, giving a clean and hyper-ordered veneer to the rarely seen underbelly of a mammoth skyscraper.

 © Flickr user Timothy Vogel

Flickr用户TimothyVogel

从第10层开始，建筑呈现出更典型的20世纪70年代高层建筑的形式。幕墙系统将金属覆层和条形窗的条纹固定在一起，用水平条带包裹建筑物的透明壁，该水平条带在视觉上增厚其存在。将结构装置从FASTMade中拉出，留下干净的饰面，该饰面与建筑物的正式清晰度很好地工作。在北轮廓上，四个侧面最高和最有活力的是，冠以在夜间照明的FA1Eade中的压痕视觉上有区别，好像是为建筑信标的旧类型提供了新的拍摄。

Starting at the tenth floor, the building assumes a form much more typical of 1970s high-rise architecture. The curtain wall system affixes striations of metal cladding and strip windows, wrapping the sheer walls of the building with a horizontal banding that visually thickens its presence. Structural devices are pulled back from the façade, leaving a clean finish that works well with the formal clarity of the building. On the north profile, the tallest and least dynamic of the four sides, the crown is visually differentiated through an indentation in the façade that is illuminated at night, as if to offer a new take on the age-old typology of the architectural beacon.

Starting at the tenth floor, the building assumes a form much more typical of 1970s high-rise architecture. The curtain wall system affixes striations of metal cladding and strip windows, wrapping the sheer walls of the building with a horizontal banding that visually thickens its presence. Structural devices are pulled back from the façade, leaving a clean finish that works well with the formal clarity of the building. On the north profile, the tallest and least dynamic of the four sides, the crown is visually differentiated through an indentation in the façade that is illuminated at night, as if to offer a new take on the age-old typology of the architectural beacon.

 © Flickr user Reading Tom

3.Flickr用户阅读Tom

虽然建筑师HughStubins创造了这座建筑的标志性建筑，但项目的大部分信贷通常都交给了它的结构工程师威廉·勒梅苏里耶。在规模庞大、规模空前庞大的情况下，发明一个支撑这种不寻常的设计的结构体系的任务正好落在他的肩上。LeMesurier设计了一个V形支架，该系统跨越了八层单元中的建筑，导致五套倒置的人字形支撑。在教科书图解形式中，这些支柱将建筑物的向下作用力转向其中心，在该中心，承重墩将它们转移到地面，所有这些支柱对由风产生的水平力提供阻力。

While the architect Hugh Stubbins created the iconic form of the building, most of the credit for the project is generally given to its structural engineer, William Le Messurier. Working on an enormous scale with an unprecedented massing configuration, the task of inventing a structural system to support this unusual design fell squarely on his shoulders. Le Messurier devised a V-shaped system of braces that spanned the building in eight-story units, resulting in five sets of inverted chevron-like supports. In textbook diagrammatic form, these braces redirect the downward forces of the building toward its center where the load-bearing piers transfer them to the ground, all the while providing resistance to the horizontal forces generated by the wind.

While the architect Hugh Stubbins created the iconic form of the building, most of the credit for the project is generally given to its structural engineer, William Le Messurier. Working on an enormous scale with an unprecedented massing configuration, the task of inventing a structural system to support this unusual design fell squarely on his shoulders. Le Messurier devised a V-shaped system of braces that spanned the building in eight-story units, resulting in five sets of inverted chevron-like supports. In textbook diagrammatic form, these braces redirect the downward forces of the building toward its center where the load-bearing piers transfer them to the ground, all the while providing resistance to the horizontal forces generated by the wind.

 © Flickr user Timothy Vogel

Flickr用户TimothyVogel

为了保持高效率和低质量，完成的结构被建造到最小的安全系数，这个决定最终会困扰工程师们。因此，这座建筑不寻常的轻盈使得它在风中受到巨大晃动的影响。LeMessurier转向了相对新颖的调谐质量阻尼器的发明，以帮助弥补重量的不足，将400吨的混凝土块放置在建筑物的顶部，就在尖顶之下的尖角屋顶。为了减少建筑物的晃动，电动阻尼器被设计成与建筑物同步移动，同时减慢了它的运动速度。它是美国第一台调谐质量阻尼器，它工作得非常完美，抵消了塔的不寻常设计，让它的性能像它的传统配置的邻居。

To keep it hyper-efficient and low on mass, the finished structure was built to a minimal safety factor, a decision that would eventually come to haunt the engineers. As a result, the building's unusual lightness made it subject to large sways in the wind. Le Messurier turned to the relatively novel invention of the tuned mass damper to help compensate for the lack of weight, placing a four hundred-ton block of concrete in the pinnacle of the building just beneath the sharply angled roof. In order to reduce building sway, the electricity-powered damper was programmed to move in sync with the building while slowing down the speed of its movements. The first tuned mass damper of its kind in the United States, it has worked to perfection, offsetting the tower’s unusual design and allowing it to behave like its more conventionally configured neighbors.

To keep it hyper-efficient and low on mass, the finished structure was built to a minimal safety factor, a decision that would eventually come to haunt the engineers. As a result, the building's unusual lightness made it subject to large sways in the wind. Le Messurier turned to the relatively novel invention of the tuned mass damper to help compensate for the lack of weight, placing a four hundred-ton block of concrete in the pinnacle of the building just beneath the sharply angled roof. In order to reduce building sway, the electricity-powered damper was programmed to move in sync with the building while slowing down the speed of its movements. The first tuned mass damper of its kind in the United States, it has worked to perfection, offsetting the tower’s unusual design and allowing it to behave like its more conventionally configured neighbors.

 © Flickr user Axel Drainville

Flickr用户Axel Drainville

这座建筑的工程奇迹给它带来了广泛的恶名，最终成为它的救星。建筑完工后不久，普林斯顿大学建筑系本科生黛安·哈特利(DianeHartley)试图在数学上复制这栋建筑的性能数据。就像她之前的工程师们一样，当她计算出直接施加于塔侧的风力时，这个结构没有问题去抵消它。然而，她更进一步，计算了宿营风-即同时从两面袭击建筑物的风-的影响，发现在一定风速以上，建筑物的连接处将发生屈曲，灾难性的故障即将来临。她给LeMessurier的办公室打了电话，想知道这些数字是从哪里来的，得到了一位项目工程师的即时保证，而且近20年来一直没有听到任何关于这件事的消息。

The engineering marvels of the building brought it a widespread notoriety that ended up being its saving grace. Shortly after construction was finished, Diane Hartley, an undergraduate architecture student at Princeton, attempted to mathematically replicate the performance figures of the building. Just like the engineers before her, when she calculated the force of wind applied directly to the side of the tower, the structure had no problem offsetting it. However, she went a critical step further, calculating the effect of quartering winds—that is, winds that strike the building from two sides simultaneously—and found that above a certain windspeed, the joints of the building would buckle and catastrophic failure was imminent. She phoned Le Messurier’s office to find out where the figures had gone off, received the offhand assurances of a project engineer, and didn’t hear another word about it for nearly twenty years.

The engineering marvels of the building brought it a widespread notoriety that ended up being its saving grace. Shortly after construction was finished, Diane Hartley, an undergraduate architecture student at Princeton, attempted to mathematically replicate the performance figures of the building. Just like the engineers before her, when she calculated the force of wind applied directly to the side of the tower, the structure had no problem offsetting it. However, she went a critical step further, calculating the effect of quartering winds—that is, winds that strike the building from two sides simultaneously—and found that above a certain windspeed, the joints of the building would buckle and catastrophic failure was imminent. She phoned Le Messurier’s office to find out where the figures had gone off, received the offhand assurances of a project engineer, and didn’t hear another word about it for nearly twenty years.

 © Flickr user Steven Severing-Haus

.class=‘class 1’>用户Steven Spling-Haus

同时，作为一种令人钦佩的谦逊的反映，勒梅苏里尔决定调查学生的问题，并意识到哈特利的数字是正确的。一项后期的成本削减措施取代了螺栓连接的拼接对角线支撑中的完全焊接接头，导致强度不足以抵挡四分五裂的风，并且由于力的错误组合，建筑物最终可能会倒塌。LeMessurier很快将这些数据交给了几位气象专家，以确定纽约结构故障所需风速的频率。答案是令人作呕的：他们说，每隔54年，除非一场风暴切断调谐质量阻尼器的电源，否则潜在灾难性风暴的频率将减少到十六年。

Meanwhile, in a reflection of admirable humility, Le Messurier decided to look into the student’s questions and realized that Hartley’s figures were correct. A late-stage cost-cutting measure that substituted fully welded joints in the spliced diagonal braces for bolted joints resulted in insufficient strength to withstand the quartering winds, and given the wrong combination of forces, the building could eventually collapse. Le Messurier quickly handed the figures to several meteorological experts to determine how frequently the wind speeds necessary for structural failure occurred in New York. The answer was sickening: every fifty-four years, they said, unless a storm cut off power to the tuned mass damper, which would reduce the frequency of potentially catastrophic storms to a mere sixteen years.

Meanwhile, in a reflection of admirable humility, Le Messurier decided to look into the student’s questions and realized that Hartley’s figures were correct. A late-stage cost-cutting measure that substituted fully welded joints in the spliced diagonal braces for bolted joints resulted in insufficient strength to withstand the quartering winds, and given the wrong combination of forces, the building could eventually collapse. Le Messurier quickly handed the figures to several meteorological experts to determine how frequently the wind speeds necessary for structural failure occurred in New York. The answer was sickening: every fifty-four years, they said, unless a storm cut off power to the tuned mass damper, which would reduce the frequency of potentially catastrophic storms to a mere sixteen years.

勒梅斯索耶赶紧联系花旗集团的高管，让他们知道他们的全新的，1.175亿美元的图标很容易成为纽约历史上最大的灾难。他们一起画了一个计划，把全焊接的钢板叠加在支架上的弱关节上，并开始在时钟周围加强建筑，同时密切关注天气预报。与高层政府官员和美国红十字会一道，他们还为市中心地区准备了12块疏散计划，以防倒塌。但与整个行动完全保密的事实相比，所有这些都是不显著的。花旗集团大楼内的一名工人或其任何邻居都意识到了上述威胁，数百名官员、焊工和伪造者成功地将此事从媒体中赶走。令人难以置信的是，直到1995年，“第五十九条故事危机”终于出版在《纽约客》杂志上了。BBC随后在电视上播出了一个关于附近小姐的特别节目，除了一个不相信的黛安哈特利之外，还没有一个人观看。

Le Messurier hurriedly contacted the executives at Citigroup to let them know that their brand new, $175 million icon could easily become the greatest disaster in New York's history. Together, they hatched a plan to superimpose fully welded steel plates over the weak joints on the braces, and began fortifying the building around the clock while keeping a watchful eye on the weather forecast. In conjunction with high-up government officials and the American Red Cross, they also prepared a 12-block evacuation plan for the midtown area in case collapse became imminent. But all of this was unremarkable compared to the fact that the entire operation was conducted in total secrecy. Not a single worker in the Citigroup building or any of its neighbors was made aware of the threat looming above them, and the hundreds of officials, welders and forgers that were brought into the fold successfully kept the affair away from the media. Incredibly, the story remained buried until 1995, when “The Fifty-Nine Story Crisis” was finally published in The New Yorker Magazine. BBC subsequently televised a special program about the near miss, watched by none other than the fiancé of an incredulous Diane Hartley.

Le Messurier hurriedly contacted the executives at Citigroup to let them know that their brand new, $175 million icon could easily become the greatest disaster in New York's history. Together, they hatched a plan to superimpose fully welded steel plates over the weak joints on the braces, and began fortifying the building around the clock while keeping a watchful eye on the weather forecast. In conjunction with high-up government officials and the American Red Cross, they also prepared a 12-block evacuation plan for the midtown area in case collapse became imminent. But all of this was unremarkable compared to the fact that the entire operation was conducted in total secrecy. Not a single worker in the Citigroup building or any of its neighbors was made aware of the threat looming above them, and the hundreds of officials, welders and forgers that were brought into the fold successfully kept the affair away from the media. Incredibly, the story remained buried until 1995, when “The Fifty-Nine Story Crisis” was finally published in The New Yorker Magazine. BBC subsequently televised a special program about the near miss, watched by none other than the fiancé of an incredulous Diane Hartley.

 Typical Floor Plan. Image © viewthespace.com

典型的平面图。图片(viewespace.com)

对于建筑师来说，这个项目引发了一系列挑衅性的道德和专业问题，给勒梅苏里尔和他的团队的英勇努力投下了更为险恶的阴影。如果没有在维修过程中立即通知公众，让公众知道失败的建筑所构成的潜在灾难性威胁，这一义务就会被正当利益所抵消，即避免大规模恐慌，以及对企业和职业声誉的不那么合理的担忧。此外，虽然这当然并不意味着建筑师更积极的监督可以避免结构故障，但这个故事要求重新考虑如何协调复杂项目上的协作努力。如果需要一系列不幸的事件来实现结构安全利润率低、后期预算替代、没有考虑到必要的环境条件等一系列不幸事件，那么，那些对该项目持更为全面和全面观点的个人，可能会提出一系列同样不同的反修正方案。建筑师和工程师可以从花旗大厦的错误和成就中吸取无数的教训，这也许是他们长期被公众隐瞒的最大耻辱。

For architects, the project prompts a series of provocative ethical and professional questions that cast a more sinister shadow over the otherwise heroic efforts of Le Messurier and his team. The duty to inform the public of potentially catastrophic threats posed by failing architecture, if not during repairs then immediately after, is counteracted by legitimate interests in avoiding mass panic and less-legitimate concerns over corporate and professional reputation. Furthermore, while certainly not implying that more active oversight by the architect could have avoided the structural failures, this story begs a reconsideration of how collaborative efforts on complex projects are coordinated. If a series of unfortunate events were required to bring about the near miss—low structural safety margins, late-stage budgetary substitutions, the failure to account for necessary environmental conditions—an equally varied array of counter fixes could have been proposed by individuals with a more comprehensive and holistic perspective on the project. There are countless ways that architects and engineers can learn from the mistakes and achievements of the Citigroup Building, and it is perhaps the greatest shame of all that they were kept hidden from the public for so long. 

For architects, the project prompts a series of provocative ethical and professional questions that cast a more sinister shadow over the otherwise heroic efforts of Le Messurier and his team. The duty to inform the public of potentially catastrophic threats posed by failing architecture, if not during repairs then immediately after, is counteracted by legitimate interests in avoiding mass panic and less-legitimate concerns over corporate and professional reputation. Furthermore, while certainly not implying that more active oversight by the architect could have avoided the structural failures, this story begs a reconsideration of how collaborative efforts on complex projects are coordinated. If a series of unfortunate events were required to bring about the near miss—low structural safety margins, late-stage budgetary substitutions, the failure to account for necessary environmental conditions—an equally varied array of counter fixes could have been proposed by individuals with a more comprehensive and holistic perspective on the project. There are countless ways that architects and engineers can learn from the mistakes and achievements of the Citigroup Building, and it is perhaps the greatest shame of all that they were kept hidden from the public for so long. 

 © Flickr user tsaiproject

Flickr用户tsaiproject

[1]Werner，Joel。“几乎消灭了纽约摩天大楼的设计缺陷。”石板。2014年4月17日。2014年10月20日检索网址：http：/www.slate.com/blog/the_ye/2014/04/17/the_Citicorp_Tower_Design_缺陷_the_HAY_WORKUT_OUT_the_摩天大楼.

[1] Werner, Joel. “The Design Flaw that Almost Wiped Out an NYC Skyscraper.” Slate. 17 April 2014. Retrieved 20 October 2014 from http://www.slate.com/blogs/the_eye/2014/04/17/the_citicorp_tower_design_flaw_that_could_have_wiped_out_the_skyscraper.html.

[1] Werner, Joel. “The Design Flaw that Almost Wiped Out an NYC Skyscraper.” Slate. 17 April 2014. Retrieved 20 October 2014 from http://www.slate.com/blogs/the_eye/2014/04/17/the_citicorp_tower_design_flaw_that_could_have_wiped_out_the_skyscraper.html.

[2]“火星”，罗曼。“结构完整性”，99%不可见(Podcast)，2014年4月15日。

[2] Mars, Roman. “Structural Integrity.” 99% Invisible (Podcast), 15 April 2014.

[2] Mars, Roman. “Structural Integrity.” 99% Invisible (Podcast), 15 April 2014.

建筑师Hugh Stubbins，WilliamLe Messurier位置：列克星敦大道601号1300000.0英尺2工程年1977年Flickr用户Paulkhor，Flickr用户Steven Senging-Haus，Flickr用户Jeff Stvan，Flickr用户Axel Drainville，Flickr用户TimothVogel，Flickr用户Read Tom，Flickr用户Ttsaiproject，viewthacep.com

Architects Hugh Stubbins, William Le Messurier Location 601 Lexington Avenue Area 1300000.0 ft2 Project Year 1977 Photographs Flickr user paulkhor, Flickr user Steven Severing-Haus, Flickr user Jeff Stvan, Flickr user Axel Drainville, Flickr user Timothy Vogel, Flickr user Reading Tom, Flickr user tsaiproject, viewthespace.com Category Skyscrapers

Architects Hugh Stubbins, William Le Messurier Location 601 Lexington Avenue Area 1300000.0 ft2 Project Year 1977 Photographs Flickr user paulkhor, Flickr user Steven Severing-Haus, Flickr user Jeff Stvan, Flickr user Axel Drainville, Flickr user Timothy Vogel, Flickr user Reading Tom, Flickr user tsaiproject, viewthespace.com Category Skyscrapers