Ситикорп центр ошибка при строительстве

Фатальная ошибка в проектировании «левитирующего» небоскреба чуть не привела к грандиозной катастрофе (Сiticorp Center, Манхэттен).

Этот примечательный во всех отношениях небоскреб много лет удивляет и радует глаз не только необычной «короной», его «левитирующие» способности просто сражают наповал. Причем не только в прямом, но и переносном смысле слова. Хотя все начиналось очень даже эффектно. Один из самых узнаваемых небоскребов Нью–Йорка – Ситикорп центр (теперь Citigroup Center) был разработан еще в начале 70-х годов прошлого века архитектором Хью Стаббинсом и инженером Уильямом Ле Месерьером.

Чтобы поместить и церковь Святого Петра, и небоскреб, последний пришлось устанавливать на высокие опоры (Сiticorp Center, Манхэттен).

Их задача состояла в том, чтобы на небольшом клочке земли, 30 % которого занимала старинная церковь Святого Петра, рассчитать расположение не только религиозного объекта, но и 59-этажного небоскреба высотой 279 м. Чтобы выполнить эту сложнейшую задачу, инженер-строитель предложил взгромоздить высотку на 30-метровые опоры, под которыми и построили новую церковь. Причем эти гигантские колонны, которые никак не отвечали строительным нормам, применимым в отношении высотных башен, были расположены не по углам конструкции, а внутри ее основания, что вообще выходило за все рамки разумного расчета.

Религиозное сооружение легко поместилось под бетонными колоннами высотой в 30,5 м Сiticorp Center. (Манхэттен, США).

Но новаторский подход Ле Месерьера никого не насторожил, ведь подкупал оригинальный внешний вид, да и запас прочности конструкции согласно расчетам был вполне достаточным. Поэтому было дано добро на строительство столь изящного здания, многие годы считавшегося настоящим чудом. Еще бы, «парящий» небоскреб – это фантастическое зрелище, которое не имело аналогов в целом мире.

Особая конструкция стропил позволяет удерживать здание даже при внутреннем расположении опор, без задействования его углов (Сiticorp Center, Манхэттен).

Конечно же, автор конструкции разработал особенную систему несущих треугольных стропил-шевронов, которые принимали на себя основной вес строения. Именно они участвуют в распределении растягивающих боковых нагрузок (во время порывов ветра) к центру колонн. Все бы ничего, но при расчете выносливости конструкции при ураганных ветрах, скорость которых равна 110 м/с, учитывалось только давление на стены, но не на углы здания. Впридачу к этому просчету, подрядчик решил сэкономить на сварных работах в местах соединения балок. Вместо сварных швов элементы конструкции скрепили болтами.

В 1977 г. небоскреб был торжественно открыт (Сiticorp Center, Манхэттен).

После окончания строительных и отделочных работ «парящий» над землей Ситикорп центр был сдан в эксплуатацию. И если бы случайный интерес всего одного человека, то при первом же ураганном ветре, несущемся по диагонали, рухнул бы не только этот небоскреб, но и ряд зданий, находящихся рядом, вызвав при этом эффект домино. По скромным подсчетам, обрушение одного лишь небоскреба могло повлечь за собой разрушение целого делового квартала с многомиллионными убытками и человеческими жертвами (по оценкам, до 200 тыс. человек).

Диана Хартли, будучи еще студенткой университета, нашла ошибку в расчетах небоскреба Сiticorp Center.

Но этого не случилось благодаря студентке инженерно-строительного факультета Диане Хартли, которая писала работу об этом удивительном строении и нашла ошибку в расчетах. При встрече с самим Уильямом Ле Месерьером, она высказала это предположение, но именитый инженер лишь только посмеялся над этим, но все же сомнения закрались. Он решил перепроверить все сам и даже подключил крупных специалистов в этой отрасли. Результаты расчетов действительно оказались неутешительны. Положение усугублял тот факт, что углы стальной конструкции были не сварены, как планировались, а это в разы уменьшало прочность небоскреба.

После обнаружения ошибки в строительстве, был составлен проект реконструкции (Сiticorp Center, Манхэттен).

Интересный факт: После того, как Уильяму Ле Месерьеру стало известно о конструкторской ошибке, было рассчитано, что избежать падения здания при скорости диагонального ветра 112 км/ч не удастся. Главный разработчик понял, что его проект потерпел фиаско, поэтому он отправился в свое укромное убежище на озере Себейго. Инженер понимал, что ему грозит судебное разбирательство и позор, поэтому решил наложить на себя руки, но вовремя спохватился, ведь в его силах было спасти жизни сотен тысяч людей. Ему пришлось официально признать этот плачевный факт и честно все рассказать владельцам Сiticorp Center и архитектору, проектировавшему это здание. Ле Месерьер даже предложил владельцам компенсацию в 2 млн дол., хотя впоследствии они потратили восемь, но это мелочи, по сравнению с тем, во сколько бы вылилось падение небоскреба.

Сварные работы в небоскребе велись в строжайшей секретности (Сiticorp Center, Манхэттен).

В срочном порядке начались укрепительные мероприятия, которые проводились тайком, чтобы не поднялась паника. На этот раз рабочим пришлось потратить 3 месяца, чтобы исправить оплошность как инженера, так и строителей. Они заменили 200 болтовых соединений на сварные швы. Счастливому спасению небоскреба поспособствовала и сама природа, ведь на Нью-Йорк надвигался мощнейший ураган Элла, критическая скорость которого достигала 220 км/ч. Но он внезапно повернул и обошел Нью-Йорк стороной, не став испытанием на прочность.

На верхних этажах башни установили инерционный демпфер (Сiticorp Center, Манхэттен).

Чтобы еще больше укрепить высотное здание, Ле Месерьер рассчитал, где и как установить 410–тонный инерционный демпфер, способный преобразовать кинетическую энергию в силу трения. С тех пор гигантский бетонный блок, расположенный на верхних этажах небоскреба, стабилизирует конструкцию, уменьшая раскачивание сооружения во время сильных порывов ветра.

В 2002 г. одну из колонн усилили щитами из стали и меди для защиты здания от возможного теракта (Сiticorp Center, Манхэттен).

И самое интересное, информация о промахе была настолько засекречена, что даже вездесущие журналисты не узнали об этом, хотя к секретным работам привлекались не только сварщики и проектировщики, но 2 тыс. сотрудников Красного Креста. Эту организацию подключили в связи с угрозой приближения урагана, сразу же после разработки плана эвакуации в случае обрушения.

Казалось бы, строительство небоскребов поставлено на поток и ошибок быть не должно. Но не там то было, когда бизнесмены пытаются сэкономить как на дорогущем клочке земли, так и на материалах. Такая вопиющая безответственность чуть не стала причиной грандиозной катастрофы, в которой могло погибнуть минимум 200 тыс. жителей и гостей Манхэттена (Нью-Йорк).

А случился фатальный просчет при строительстве «левитирующего» небоскреба Ситикорп центр, под которым решили пристроить церковь.

Этот примечательный во всех отношениях небоскреб много лет удивляет и радует глаз не только необычной «короной», его «левитирующие» способности просто сражают наповал. Причем не только в прямом, но и переносном смысле слова. Хотя все начиналось очень даже эффектно. Один из самых узнаваемых небоскребов Нью–Йорка – Ситикорп центр (теперь Citigroup Center) был разработан еще в начале 70-х годов прошлого века архитектором Хью Стаббинсом и инженером Уильямом Ле Месерьером.

Их задача состояла в том, чтобы на небольшом клочке земли, 30 % которого занимала старинная церковь Святого Петра, рассчитать расположение не только религиозного объекта, но и 59-этажного небоскреба высотой 279 м. Чтобы выполнить эту сложнейшую задачу, инженер-строитель предложил взгромоздить высотку на 30-метровые опоры, под которыми и построили новую церковь. Причем эти гигантские колонны, которые никак не отвечали строительным нормам, применимым в отношении высотных башен, были расположены не по углам конструкции, а внутри ее основания, что вообще выходило за все рамки разумного расчета.

Но новаторский подход Ле Месерьера никого не насторожил, ведь подкупал оригинальный внешний вид, да и запас прочности конструкции согласно расчетам был вполне достаточным. Поэтому было дано добро на строительство столь изящного здания, многие годы считавшегося настоящим чудом. Еще бы, «парящий» небоскреб – это фантастическое зрелище, которое не имело аналогов в целом мире.

Конечно же, автор конструкции разработал особенную систему несущих треугольных стропил-шевронов, которые принимали на себя основной вес строения. Именно они участвуют в распределении растягивающих боковых нагрузок (во время порывов ветра) к центру колонн. Все бы ничего, но при расчете выносливости конструкции при ураганных ветрах, скорость которых равна 110 м/с, учитывалось только давление на стены, но не на углы здания. Впридачу к этому просчету, подрядчик решил сэкономить на сварных работах в местах соединения балок. Вместо сварных швов элементы конструкции скрепили болтами.

После окончания строительных и отделочных работ «парящий» над землей Ситикорп центр был сдан в эксплуатацию. И если бы случайный интерес всего одного человека, то при первом же ураганном ветре, несущемся по диагонали, рухнул бы не только этот небоскреб, но и ряд зданий, находящихся рядом, вызвав при этом эффект домино. По скромным подсчетам, обрушение одного лишь небоскреба могло повлечь за собой разрушение целого делового квартала с многомиллионными убытками и человеческими жертвами (по оценкам, до 200 тыс. человек).

Но этого не случилось благодаря студентке инженерно-строительного факультета Диане Хартли, которая писала работу об этом удивительном строении и нашла ошибку в расчетах. При встрече с самим Уильямом Ле Месерьером, она высказала это предположение, но именитый инженер лишь только посмеялся над этим, но все же сомнения закрались. Он решил перепроверить все сам и даже подключил крупных специалистов в этой отрасли. Результаты расчетов действительно оказались неутешительны. Положение усугублял тот факт, что углы стальной конструкции были не сварены, как планировались, а это в разы уменьшало прочность небоскреба.

После того, как Уильяму Ле Месерьеру стало известно о конструкторской ошибке, было рассчитано, что избежать падения здания при скорости диагонального ветра 112 км/ч не удастся. Главный разработчик понял, что его проект потерпел фиаско, поэтому он отправился в свое укромное убежище на озере Себейго. Инженер понимал, что ему грозит судебное разбирательство и позор, поэтому решил наложить на себя руки, но вовремя спохватился, ведь в его силах было спасти жизни сотен тысяч людей. Ему пришлось официально признать этот плачевный факт и честно все рассказать владельцам Сiticorp Center и архитектору, проектировавшему это здание. Ле Месерьер даже предложил владельцам компенсацию в 2 млн дол., хотя впоследствии они потратили восемь, но это мелочи, по сравнению с тем, во сколько бы вылилось падение небоскреба.

В срочном порядке начались укрепительные мероприятия, которые проводились тайком, чтобы не поднялась паника. На этот раз рабочим пришлось потратить 3 месяца, чтобы исправить оплошность как инженера, так и строителей. Они заменили 200 болтовых соединений на сварные швы. Счастливому спасению небоскреба поспособствовала и сама природа, ведь на Нью-Йорк надвигался мощнейший ураган Элла, критическая скорость которого достигала 220 км/ч. Но он внезапно повернул и обошел Нью-Йорк стороной, не став испытанием на прочность.

Чтобы еще больше укрепить высотное здание, Ле Месерьер рассчитал, где и как установить 410–тонный инерционный демпфер, способный преобразовать кинетическую энергию в силу трения. С тех пор гигантский бетонный блок, расположенный на верхних этажах небоскреба, стабилизирует конструкцию, уменьшая раскачивание сооружения во время сильных порывов ветра.

И самое интересное, информация о промахе была настолько засекречена, что даже вездесущие журналисты не узнали об этом, хотя к секретным работам привлекались не только сварщики и проектировщики, но 2 тыс. сотрудников Красного Креста. Эту организацию подключили в связи с угрозой приближения урагана, сразу же после разработки плана эвакуации в случае обрушения.

А вот еще есть такие небоскребы на ножках — Rainier Tower : дом на ножке или например вот дом на многоножках

Ситикорп–центр в Нью–Йорке

С его примечательной сорокапятиградусной диагональной «короной», здание Ситикорп–центра является одним из самых узнаваемых небоскрёбов в Нью–Йорке. Оно имеет пятьдесят девять этажей и стоит на третьем месте в списке самых высоких зданий Манхэттена. А на момент своего строительства Ситикорп–центр был седьмым по высоте зданием в мире. На первый взгляд кажется, что огромный небоскрёб парит над Лексингтон–авеню; однако на самом деле его удерживают четыре массивных столба высотой 35 метров, расположенные в центре каждой стороны, а не по углам. Такая необычная конструкция была вызвана необходимостью – здание должны были построить возле достопримечательности, церкви Святого Петра – однако при его проектировании была допущена серьёзная ошибка, которую никто не заметил во время строительства и первоначальной эксплуатации. Если бы эту ошибку случайно не обнаружили и тайно не исправили, то могучий небоскрёб могло бы неожиданно снести сильным порывом ветра.

Структурный каркас здания был разработан инженером по имени Уильям Ле Месерьер в начале 1970–х годов. Церковь Святого Петра представляла собой большую проблему, однако Ле Месерьер был очень способным и творческим инженером. Он решил построить здание на столбах высотой с девятиэтажный дом. Небоскрёб также имел одну, более узкую опору в самом центре: она скрывала шахты лифтов и обеспечивала дополнительную прочность конструкции. Такой дизайн не позволял зданию загораживать церковь, которая располагалась у его северо–западного угла, и создавал изящный «парящий эффект».

Концепция, предложенная Ле Месерьером, была вполне разумной: проект здания выглядел красиво и изящно. Его стальная надстройка весила всего 25 тысяч тонн и была удивительно лёгкой, по сравнению с другими небоскрёбами, такими как Эмпайр–стейт–билдинг (вес его каркаса составляет 60 тысяч тонн). Из–за столбов и небольшого веса конструкции Ситикорп–центра Ле Месерьер в свои планы также включил установку на верхних этажах здания инерционного демпфера, 410–тонного бетонного блока, управляемого автоматической системой. Это стабилизирующее оборудование внушительных размеров было предназначено для того, чтобы в два раза уменьшить раскачивание здания путём преобразования кинетической энергии в силу трения.

Ле Месерьер впервые обнаружил ошибку в проектировании Ситикорп–центра в 1978 году, примерно через год после завершения его строительства. Студентка инженерного факультета по имени Диана Хартли связалась с ним, чтобы задать несколько вопросов, связанных с дизайном здания. Ле Месерьер охотно согласился ответить на них. Профессор, который преподавал Хартли, выразил сомнения по поводу прочности небоскрёба на столбах, которые располагались не по углам. «Передайте своему преподавателю, что он несёт полную чушь, – сказал Ле Месерьер Диане Хартли, – поскольку он не знает о проблеме, которую нам довелось решать». Он продолжил говорить о том, что такая конструкция здания позволяет ему идеально вписываться в отведённое пространство и выдерживать сильные порывы ветра, даже под диагональным углом.

Однако этот разговор заставил его призадуматься, и он решил провести некоторые расчёты, связанные с определением силы диагонального ветра, которую способна выдержать конструкция. Он был особенно заинтересован в последствиях «оправданных» изменений в проектировании, сделанных во время строительства: многочисленные швы скреплялись при помощи болтов, а не сварки. Обычно такие изменения считались приемлемыми, однако дизайн Ситикорп–центра был необычайно чувствителен к диагональным ветрам, что не было учтено строителями. Результаты вычислений Ле Месерьера были тревожными.

Сила ветра, воздействующая на плоские поверхности любого здания, является невероятно огромной. Ветер оказывает немалое воздействие на основание высотного здания, однако гравитация посредством компрессии не позволяет зданию развалиться на части. Здание защищено от ветра до тех пор, пока швы остаются достаточно прочными для того, чтобы противостоять силе ветра. Ле Месерьер переживал, что болты, которые скрепляли швы Ситикорп–центра, были недостаточно прочными для выполнения этой задачи.

Он показал свои расчёты знакомому инженеру Алану Дэвенпорту, который был специалистом в сфере, связанной с поведением зданий в условиях сильного ветра. Дэвенпорт обнаружил, что скорости ветра, равной 112 километрам в час, будет достаточно для того, чтобы повредить болты, соединяющие швы, и привести к разрушению Ситикорп–центра. Таких сильных ветров в Нью–Йорке никогда не было, да и вообще: бури подобного масштаба случались примерно раз в шестнадцать лет. Однако стремительно приближался сезон ураганов, и Дэвенпорт и Ле Месерьер были единственными людьми в мире, кто знал о том, что обитатели нового небоскрёба «Ситикорп–центр» стоимостью 175 миллионов долларов могли стать жертвами его катастрофического разрушения.

Ситикорп–центр возвышается над церковью Святого Петра

Напуганный такой возможностью, Ле Месерьер бежал в свой укромный уголок на озере Себейго, где он хотел проанализировать полученные результаты и рассмотреть возможные варианты. Поскольку Ле Месерьер мог столкнуться с судебным разбирательством, банкротством и профессиональным позором, он начал подумывать о самоубийстве, однако потом его внезапно осенило, что он владел информацией, которую можно было бы применить для того, чтобы спасти тысячи жизней. На следующий день он начал делать телефонные звонки. После разговора с корпоративными юристами и консультации с Лесли Робертсоном, инженером, который помогал проектировать Всемирный торговый центр, Ле Месерьер отправился в Кембридж, чтобы проинформировать о ситуации Хью Стаббинса, архитектора, разработавшего проект здания Ситикорп–центра. Стаббинс вздрогнул, когда он услышал новости.

Вместе они вылетели в Нью–Йорк, чтобы сообщить о проблеме владельцам Ситикорп–центра. «У меня есть для Вас плохие новости, сэр», – сказал Ле Месерьер исполнительному вице–президенту «Ситикорп», Джону Риду. Двое мужчин обозначили недостаток конструкции и предложили своё решение: планомерно укрепить все 200+ болтовых соединений при помощи сварки.

К работе приступили немедленно; она завершилась спустя три месяца. Сварщики работали ночью, а плотники – днём. На случай неминуемой катастрофы был подготовлен план эвакуации, однако широкая общественность ничего не знала о ситуации… Работники прессы в то время бастовали, поэтому новости о ремонте не распространялись среди населения.

Примерно спустя полтора месяца после начала ремонтных работ возникла угроза в виде урагана Элла, который как раз держал курс на Манхэттен, однако, к счастью, он сменил направление, не став проверять на прочность наполовину отремонтированное задание. Работы по укреплению болтовых соединений были завершены в сентябре 1978 года. После этого здание было признано одним из самых прочных небоскрёбов в мире.

Данный инцидент скрывали от общественности на протяжении двадцати лет. Статья о нём появилась в «New Yorker» в 1995 году.

Диана Хартли

Студентка Диана Хартли, которая обнаружила ошибку и сообщила об этом Ле Месерьеру, спасла сотни жизней и помогла сэкономить миллионы долларов. Что касается Ле Месерьера, владельцы «Ситикорп» получили от него компенсацию в размере двух миллионов долларов, несмотря на то, что ремонт им обошёлся в восемь миллионов долларов. Говорят, что их настолько впечатлила прямолинейность Ле Месерьера, что они решили не выдвигать против него никаких обвинений. Некоторые люди высмеивают тот факт, что Ле Месерьер так легко отделался благодаря тому, что просто признал свою ошибку, однако реальность такова, что он был готов взять на себя ответственность за вещи, которые были вне его контроля, чтобы спасти город от неминуемой катастрофы.

источник

Не очень-то курьи ножки.

The Citigroup Center (formerly Citicorp Center and also known by its address, 601 Lexington Avenue) is an office skyscraper in the Midtown Manhattan neighborhood of New York City. Built in 1977 to house the headquarters of Citibank, it is 915 ft (279 m) tall and has 59 floors with 1.3×10⁶ sq ft (120,000 m²) of office space. The building was designed by architect Hugh Stubbins, associate architect Emery Roth & Sons, and structural engineer William LeMessurier.

601 Lexington Avenue takes up much of a city block bounded clockwise from west by Lexington Avenue, 54th Street, Third Avenue, and 53rd Street. The building has a 45° angled top with a base on four stilts, as well as a six-story office annex to the east. The tower overhangs St. Peter’s Evangelical Lutheran Church at Lexington Avenue and 54th Street, a standalone granite structure designed simultaneously by Stubbins. Also at the base is a sunken plaza, a shopping concourse, and entrances to the church and the New York City Subway’s Lexington Avenue/51st Street station. The tower stories are supported by stacked load-bearing braces in the form of inverted chevrons. Upon Citicorp Center’s completion, it received mixed reviews from architectural critics, but also several architectural accolades.

Land acquisition for what became Citicorp Center commenced in 1968 and took five years. St. Peter’s Church sold its plot on the condition that a new church building be constructed at the base of the tower. The design was announced in July 1973 and the structure was completed in October 1977. During the Citicorp Center engineering crisis less than a year after the building’s completion, emergency repairs were made after the tower was discovered to be vulnerable to collapse due to wind. The building was acquired by Boston Properties and Citicorp Center was renamed 601 Lexington Avenue in the 2000s. The New York City Landmarks Preservation Commission designated 601 Lexington Avenue as a city landmark in 2016. Over the years, the atrium, plaza, and other public spaces have been renovated.

Site[edit]

The building is in the Midtown Manhattan neighborhood of New York City. It takes up the majority of a city block bounded by Lexington Avenue to the west, 54th Street to the north, Third Avenue to the east, and 53rd Street to the south. The land lot covers 70,572 sq ft (6,556.4 m²) with a frontage of 200 ft (61 m) on Lexington Avenue and a depth of 325 ft (99 m).^[4] The only other building on the block is 880 Third Avenue, an 18-story structure at 53rd Street and Third Avenue.^[4][5] Other nearby buildings include 599 Lexington Avenue to the south, 100 East 53rd Street and the Seagram Building to the southwest, 399 Park Avenue to the west, the Central Synagogue to the northwest, and the Lipstick Building to the east.^[4] The New York City Subway’s Lexington Avenue/51st Street station (served by the 6, <6>​​, E, and ​M trains) is directly underneath 601 Lexington Avenue.^[6]

Custom street furniture including newsstands, flagpoles, and streetlight pylons was designed for the sidewalks around 601 Lexington Avenue and installed in 1978.^[7][8] New Jersey-based company Designetics designed pylons with a cruciform cross-section and street lamps at the top. Seven pylons are placed in the middle of the block. Three custom pylons, at the northwest, northeast, and southwest corners of the block,^[a] include pedestrian and vehicular traffic lights. The pylons were initially designed with a «glossy black finish» that contrasted with the tower’s aluminum facade;^[7][8][9] by 2016, they had been painted gray.^[7] The New Yorker described the pylons in 2017 as «sculptural towers worthy of Brancusi».^[10]

Thirty-one structures were acquired and demolished to make way for the development.^[5][11] Most of these were brownstone houses;^[12] some contained commercial spaces, ranging from small shops to the upscale Cafe Chauveron.^[12][13] The site also included the Medical Chambers on 54th Street, which was owned by forty doctors.^[12][14] The only remaining previous occupant of the site is St. Peter’s Evangelical Lutheran Church, whose sanctuary at Lexington Avenue and 54th Street, on the northwest corner of the block, was rebuilt when the Citigroup Center was developed.^[5][11]

Architecture[edit]

601 Lexington Avenue, also known as the Citigroup Center and Citicorp Center,^[3][15] was designed by architect Hugh Stubbins as the headquarters for First National City Bank (later Citibank), along with associate architect Emery Roth & Sons.^[15][16][17] Of the principals at Hugh A. Stubbins & Associates, architect Peter Woytuk was most involved in design, while project manager W. Easley Hammer oversaw construction.^[18][19] In addition, Edward Larrabee Barnes was the consulting architect,^[2][17][19] and LeMessurier Associates and James Ruderman were the structural engineers.^[16][20] The general contractor was HRH Construction Corporation^[18][20][21] and the steel contractor was Bethlehem Steel.^[20][22] Various other contractors were hired to supply material for the building.^[23]

Form and facade[edit]

The Citigroup Center is 59 stories high, with its roof about 915 ft (279 m) above ground level.^[2][3][b] Excluding unused floor numbers at the base, it contains 46 office stories.^[26][27] At the time of completion, Citicorp Center was the seventh-tallest building in the world.^[24][25] In addition to the primary 59-story tower, there is an annex at 159 East 53rd Street with six^[25][28] or seven stories.^[29] It extends east to Third Avenue and includes part of the building’s shopping concourse.^[25][28] The facades of the tower and its annex are designed similarly.^[30]

The facade is made of anodized aluminum and reflective glass panels.^[30][31][32] Each facade segment measures 12 by 9 ft (3.7 by 2.7 m) and consists of both glass panes and aluminum plates.^[33] As an energy-saving measure, the glass windows were manufactured as two panes, the inner pane of which was coated with chrome plating.^[7][31][32] The windows on each floor are separated by flush aluminum spandrels.^[34] The spandrels were manufactured by Flour City Architectural Metals, a firm based in Glen Cove, New York.^[30][35] The aluminum is silver-colored, like that on the Pepsi-Cola Building and One Chase Manhattan Plaza, because Stubbins thought a dark color would not allow observers to «see the shade and shadow».^[30] The metal panels were fitted with double the amount of insulation considered normal at the time of construction. The aluminum was polished to reflect heat from sunlight.^[7][31][32]

Roof[edit]

The triangular roof of 601 Lexington Avenue rises 160 ft (49 m) above the top story and faces south, sloping at a 45-degree angle.^{[25][28][36][c]} Before the official plans were announced in 1973, the architects had intended the roof to be terraces for apartments,^[38][39] which would have faced westward.^[30][39] There would have been about 100 apartments,^[40][41] but the New York City Department of City Planning would not approve a zoning change to permit that use.^[27][30][41] The architects then rotated the roof southward^[39][42] to accommodate flat-plate solar collectors that could produce hot water, which would be used to dehumidify air and reduce cooling energy.^[3][43] Starting in February 1975, engineers from the Massachusetts Institute of Technology conducted a twelve-month feasibility study for the installation of such a system.^[28][44][45] Afterward, the system was scrapped, either because of the low savings,^[46][47][48] refinement of mechanical systems,^[32] or disputes with the supplier.^[7]

Even after the solar-collector plans were scrapped, the design was kept; Stubbins wrote that the roof «relieves the uniformity of flat-topped towers proliferating in the center of the city».^[49][50] This made Citicorp Center the first postmodern skyscraper whose roof was designed solely for decorative purposes.^[36][51] The roof was also fitted with solar panels in 1983, when Consolidated Edison and Citibank sponsored a four-year solar panel test.^[7][52]

Exterior spaces[edit]

Plaza[edit]

A large plaza 12 ft (3.7 m) beneath street level was built along with Citicorp Center and designed by landscape architect Hideo Sasaki.^[53] The plaza was included under the 1961 Zoning Resolution,^[53] which allowed New York City developers a zoning «bonus» for including open space in front of their buildings.^[54] While many developers took advantage of the «bonus», the New York City Planning Commission found in 1975 that many of these plazas ranged from «bleak, forlorn places» to «forbidding and downright hostile».^[55][56] In response, the City Planning Commission’s Urban Design Group had been formed in 1967 to determine how to improve plaza designs,^[53][57] influencing the commission’s decision to modify the zoning laws in 1975.^[53][56] The design of 601 Lexington Avenue’s plaza was finalized in 1973 before these rule changes were enacted.^[53] However, the plaza included many of the same features that were proposed in the rule change, such as an outdoor plaza, a covered pedestrian area, and an arcade running through the city block.^[53][58]

The plaza has an area of 6,000 sq ft (560 m²).^[59] Its presence allowed the tower to be designed with a maximum floor area ratio of 18:1, higher than the 15:1 ratio specified for the area.^[27] The plaza is accessed by a set of stairs extending northeast from the corner of Lexington Avenue and 53rd Street.^[53][60] On the south side of the plaza is an entrance to the Lexington Avenue/51st Street subway station.^[61][62] This subway entrance replaces two staircases from the street, which were demolished to make way for Citicorp Center.^[53] The north side of the plaza contains the entrance to St. Peter’s Church and the east side contains an entrance to the lower lobby.^[63] During the plaza’s construction, the developers collaborated with the numerous public agencies with a stake in the project, including the Metropolitan Transportation Authority, which operated the subway station.^[34]

The plaza, interior shopping concourse, and sidewalks all initially contained brown brick floor pavers. There was also originally a fountain at the center of the plaza, which was designed to conceal noise from the environs, similar to the fountain at nearby Paley Park.^[63] 601 Lexington Avenue’s fountain was demolished in 2017.^[64]

St. Peter’s Lutheran Church[edit]

St. Peter’s Lutheran Church is on the northwest corner of the Citigroup Center site, at 619 Lexington Avenue and 54th Street.^[65] The exterior was designed by Stubbins and Hammer, while the interior was furnished by Vignelli Associates.^[8][66][67] The church occupies the same site as its old building. The congregation permitted Citicorp to erect the skyscraper only if a new church was built at the same location, structurally unconnected to the tower. Andrew Alpern and Seymour Durst characterized the agreement as «ecumenically joining God and mammon to the benefit of both».^[13][68] Additionally, at least 63 percent of the church had to contain «nothing built above it».^[67][69] According to Stubbins, the lack of structural connections would give the church a «breathing space» of its own.^[70]

The structure is within 601 Lexington Avenue’s sunken plaza, rising about 60 ft (18 m) above ground^[71] or 85 ft (26 m) in total.^[8][66][67] It contains a facade of brown Caledonia granite with ashlar.^{[66][67][71][29]} The roof is clad in copper coated with lead. The materials were meant to establish a distinct identity for the church while also associating it with 601 Lexington Avenue’s tower.^[8][67] At the top of the church, a skylight bisects the church building diagonally from southwest to northeast, allowing passersby to look into the church building.^[66][71][29] A window facing the corner of Lexington Avenue and 54th Street overlooks the pipe organ inside.^[67] Stubbins had intended the structure’s shape to resemble a pair of hands «held up in prayer with light coming between them».^[72] Arnaldo Pomodoro designed a bronze cross for the exterior, which was installed in 1982 and measures 8 ft (2.4 m) tall by 6 ft (1.8 m) wide.^[73]

The main sanctuary is adjacent to the lower plaza,^[63][74] about 5 ft (1.5 m) beneath the plaza.^[63] It has a capacity of 850 seats; the center set of pews is designed to be movable so the space could host events when needed.^[8] There was also a black-box theater, a library, kitchen, daycare center, clergy offices, dressing rooms, choir rooms, and lecture and community rooms.^[72] Upon the church’s completion, there was a two-manual, two-pedal organ with 2,175 pipes.^[75] Inside the church is the Nevelson Chapel (also known as the Chapel of the Good Shepherd), which was donated by parishioner Erol Beker^[76] and designed by sculptor Louise Nevelson.^[74][77] The 24-seat chapel^[78] measures 21 by 24 ft (6.4 by 7.3 m)^[76] and contains sculptural elements on the wall including reliefs, altarpieces, and columns.^[79][80][81] It was renovated in the 1980s,^[78] and it was restored from 2018 to 2019 by Kostow Greenwood Architects^[82][83] as part of a $5.75 million renovation partly funded by Nevelson’s Pace Gallery.^[83][84] The space was described by David W. Dunlap in 2004 as the city’s «most architecturally successful postwar sanctuary».^[85][86]

The church’s basement theater is used by the York Theatre.^[87][88] St. Peter’s Church also hosts a jazz ministry created by the Rev. John Garcia Gensel, who in 1965 became the Minister to the Jazz Community.^[89][90] The jazz ministry has sponsored several programs over the years,^[67] such as free jazz performances at the base of Citicorp Center.^[91] The church has hosted memorials or funerals for jazz musicians such as Miles Davis, Dizzy Gillespie, and Thelonious Monk.^[67] In 2021, the church was seriously damaged after a broken water main flooded its space.^[92][93]

Structural features[edit]

The tower stories are of «trussed tube» construction.^[94][95] Each of the tower stories measures 157 by 157 ft (48 by 48 m),^[20][96] or 24,600 sq ft (2,290 m²) total.^[97] Within the tower stories, the elevators and emergency stairs are embedded in a service core at the center of each story.^[98] The core is about 68 by 68 ft (21 by 21 m), while the floor space around the core is just less than 45 ft (14 m) wide.^[96] Overall, 601 Lexington Avenue contains 24,000 short tons (21,000 long tons; 22,000 t) of steel, forty percent the amount used in the Empire State Building.^[94][99]

Stilts[edit]

The tower is supported by four stilts measuring approximately 112 ft (34 m) high with a cross section of 24 by 24 ft (7.3 by 7.3 m).^{[16][28][60][d]} The stilts are underneath the centers of the tower’s outer edges, cantilevering 72 ft (22 m) outward from the core.^{[22][25][51][61]} According to Stanley Goldstein of LeMessurier’s New York City office, stilts at the center of each edge were able to withstand forces from «quartering winds» from the corners, compared to stilts that were placed at the corner. Additionally, the placement of the stilts allowed a smaller foundation than in a conventional building of similar size.^[96]

Each of the individual stilts is composed of four vertical beams, of which the outer pairs are much heavier than the inner pairs.^{[94][101][102]} This design makes each stilt similar to a vertical K-truss, which prevents the stilt from buckling.^[102] Although the stilts could have theoretically been thinner, they were enlarged to give the tower a more stable appearance. Inside the stilts are emergency stairs and mechanical ducts.^[94][101] In 2002, following the September 11 attacks the previous year, one of the stilts was reinforced with blast-resistant shields of steel and copper as well as steel bracing.^[103][104] There is also an octagonal elevator core in the middle of the building,^{[30][51][102]} which measures 63 by 72 ft (19 by 22 m)^[102] and carries the structural loads from gravity.^[101] Unlike on the upper stories, the elevator core contains only elevators, as the emergency staircases are within the stilts.^[102]

Chevrons[edit]

Above the stilts are stacked load-bearing braces in the form of inverted chevrons, which are designed to distribute tension loads from the upper stories that are created by wind.^[24][105] On each side, there are six chevrons, each of which absorb wind loads at intervals of eight stories.^{[22][51][106]} The wind loads from each eight-story tier are transferred into the center of the frame, where 60 in-wide (150 cm) «mast column transports» extend the full height of the tower.^[96][106] The mast columns are 30 in (760 mm) deep at the base, tapering to 18 ft (5.5 m) at the 40th floor. The diagonal beams that form each chevron are 14 in (360 mm) deep and connect to structural spandrels at the top of each eight-story tier, which are 36 in (910 mm) deep.^[96] The tops of each eight-story tier (where the diagonal beams meet the corner) do not contain vertical columns, thus preventing wind loads from accumulating at the tower’s corners.^[29]

The ninth story, the lowest level above the stilts, contains a trussed frame similar in design to a cantilever bridge, where the wind loads are transferred downward into the stilts.^[106][107] This story is used as a mechanical room.^[107]

The chevrons are not visible from the exterior but can be seen from the offices inside,^[24][108] in contrast to structures such as Chicago’s John Hancock Center.^[24][34][39] After Citicorp Center’s completion, W. Easley Hammer reflected that he thought it was a mistake to conceal the chevrons,^[24] while LeMessurier said that Stubbins had rejected his idea for exposed chevrons.^[22][94] The chevrons were bolted to each other with over two hundred joints; as built, these posed a serious structural danger, leading to the Citicorp Center engineering crisis.^[94][109] As a result, 2 in-thick (5.1 cm) welded steel plates were installed over each joint in 1978.^[94][110]

Interior[edit]

The tower contains approximately 1.3×10⁶ sq ft (120,000 m²) of rentable space. The office annex to the east contains about 270,000 sq ft (25,000 m²) of space.^[24] According to the Department of City Planning, the building has a gross floor area of 1,654,020 sq ft (153,663 m²),^[4] while according to The Skyscraper Center, the building has 1,578,883 sq ft (146,683.0 m²).

Base[edit]

601 Lexington Avenue’s main entrance lobby is at the middle of the Lexington Avenue frontage, across a footbridge that provides entrance to St. Peter’s Church. The main entrance consists of a double-height glass box with steel ribs, which is 70 ft (21 m) long. The lobby was constructed as part of a 2010 renovation.^[111]

There is a three-story shopping concourse at the base of the stilts, originally called the Market.^[48][112] The lowest level, corresponding to the lower lobby, includes a planted atrium measuring 85 ft (26 m) high, with a skylight measuring 90 by 100 ft (27 by 30 m).^[76][113] The corner of Third Avenue and 54th Street contained an entrance to the lowest level of the shopping concourse, while on 54th Street was an entrance to the second level.^[113] The storefronts were designed to blend in with the plaza and street, with similar floor surfaces and transparent exterior walls.^[114] Overall, the stores were intended as a commitment to the city, a corporate symbol, and a tourist attraction, according to one of Citicorp’s vice presidents, Arthur E. Driscoll.^[24][112] The bank presented a model train exhibition in the space each December from 1987 to 2009.^[115] The shopping concourse was renamed The Shops at Citicorp Center in 1995,^[116] and it is known as The Atrium as of 2016.^[117]

Mechanical features[edit]

In the office stories, the elevators and stairs are clustered in a central core.^[118] The building contains 20 double-deck elevators,^[119][120] which Otis Worldwide constructed for $7 million.^[119][121] Although each of the upper or lower decks serves only odd or even floors, visitors can travel between odd and even floors using escalators.^[38] Each of the double-deck elevators consists of two standard elevator cabs that operate simultaneously in one shaft.^[119][120] The double-deck elevators cost 25 percent more than standard elevators but allowed a 24 percent reduction in the floor area taken up by elevators;^[122] namely, twenty-six single-deck elevator shafts would have been required otherwise.^[97] 601 Lexington Avenue’s double-deck elevators were likely the first to be installed in New York City since 1932, when the Cities Service Building was completed.^[7][28] In total, 601 Lexington Avenue has 38 elevators.

Citicorp Center was also designed with other mechanical systems. At its completion, each tenant received mail from a «supermail» system. Incoming mail was sorted in the basement and transferred via lifts to each floor, where the mail was transported manually to fixed bins.^[123] The building also contained 2,500 sensors to monitor the mechanical systems, such as HVAC, lighting, electrical, sprinkler, life-safety, security, and elevator systems.^[120] The sloped roof includes mechanical equipment.^[32]

At the building’s completion, it was intended to be energy-efficient.^{[16][31][120]} The building’s water supply consisted of only cold water.^[32] Heat from the building’s mechanical systems was recirculated to warm the water supply and heat the office spaces. The office spaces were cooled with outside air wherever it was practical.^[31] The fluorescent light bars in the ceiling, manufactured by Joseph Loring & Associates, were fitted with glass shields to spread the artificial light more efficiently, thereby requiring fewer lighting fixtures.^[31][120] Even though the rooftop solar collectors were not installed, the other features allowed the building to use 42 percent less energy compared to a regular office building of the same size.^[100] However, during the summer, the building used a conventional air-conditioning system, which offset the savings from the heat-deflecting facade.^[97]

Citicorp Center was the city’s first skyscraper to feature a tuned mass damper (TMD).^{[24][29][108]} Located within the rooftop mechanical space, the TMD is designed to counteract swaying motions due to wind and reduces wind-related movement by up to fifty percent.^{[94][124][125]} The equipment weighs 400 short tons (360 long tons; 360 t) and includes a concrete block measuring 30 by 30 by 6 ft (9.1 by 9.1 by 1.8 m).^[20][24][39] The concrete block sits on a pool of oil within a steel plate and has two spring mechanisms, one each to counteract north-south and east-west movement. The equipment cost $1 million to install. By comparison, it would have cost $5 million to add mass to reduce the tower’s movement,^[108] namely 2,800 short tons (2,500 long tons; 2,500 t) of additional steel.^[126]

History[edit]

National City Bank was founded in 1812^[127] and, for over a century, had its headquarters in the Financial District of Lower Manhattan.^[5] The company was headquartered at 52 Wall Street^[128] until 1908, when it moved to 55 Wall Street.^[129][130] After National City Bank and the Farmers’ Loan and Trust Company merged in 1929,^[131] these companies expanded into a new structure at 20 Exchange Place, completed in 1931.^[132][133] City Bank Farmers Trust moved to 399 Park Avenue, one block west of the present Citigroup Center, in 1961.^[134]

On the northwestern corner of the Citigroup site was St. Peter’s Lutheran Church, which had been founded in 1862 as a German-speaking congregation.^[5][e] The church’s previous structure, a Gothic building designed by John G. Michel and P. Brandner,^[135] was completed in 1905.^[5][11][136] The congregation’s previous sanctuary at Lexington Avenue and 46th Street, which it had occupied since 1871, had been demolished in 1902 for the construction of Grand Central Terminal.^[5][11] The congregation, which at its peak had membership of over one thousand, had decreased to below 300 by the 1960s, prompting the congregation to consider relocating to near the United Nations headquarters.^[5][11][13]

Development[edit]

Site acquisition[edit]

The lots on the St. Peter’s block were acquired secretively in five and a half years starting around 1968.^[5][137] The acquisition was headed by brokers Donald Schnabel and Charles McArthur of Julien J. Studley Inc.^[13][138] The brokers believed that a large, continuous land lot would be worth more than the sum of each lot’s individual worth, though the firm had not yet secured a client for which it was purchasing the lots.^[138] Furthermore, St. Peter’s Church’s membership was once again increasing and they were loath to part with their property.^[11] Subsequently, a Studley broker formed a company called Lexman, which then approached First National City Bank to determine their interest in the St. Peter’s block, one block east of their headquarters at the time.^[5][139] Lexman gradually acquired the other lots on the block.^[137] Former Citicorp Chairman Walter B. Wriston reportedly decided to acquire several other low- and mid-rise buildings in the area, supposedly to buy out massage parlors and mom-and-pop stores in Midtown.^[140]

The firm again negotiated with St. Peter’s congregation in late 1969 after some lots had been acquired.^[18] John White, president of James D. Landauer Associates consultants, proposed that the new structure on the site be a condominium development; i.e. the church would have a partial ownership stake in the new development.^[141][142] In February 1970, the congregation signed a «letter of intent» to sell its building, as well as the air rights above the church,^[141][142] to First National City Bank.^[143][144] In exchange, the congregation received $9 million and was named as a condominium partner in the tower’s development. Subtracting the $5 million cost of the new church building, the congregation netted a $4 million profit.^{[141][143][145]}

By January 1971, Hugh Stubbins & Associates were hired to develop plans for a large building on the city block, and St. Peter’s Church had hired Edward Larrabee Barnes to represent its design interests.^[14] The Stubbins firm was then relatively inexperienced in designing high-rise buildings.^[13] The New York Times characterized the site as an «annex» to First National City Bank’s main building at 399 Park Avenue.^[14][141] The congregation of St. Peter’s Church voted in May 1971 to approve the sale and construct a new structure on the same site,^[146][147] and they relocated in early 1973 to a temporary location at the Central Presbyterian Church.^[148] By July 1973, land acquisition was virtually complete,^[149] although the last parcel was not acquired until November 1975, when the lot at 884 Third Avenue was purchased.^[141] The acquisition cost was $40 million, making the site the most expensive city block on earth.^[19][144] The only lot not acquired was 880 Third Avenue, which had been completed in 1965, and which the brokers considered too new to be demolished.^[13]

Construction[edit]

In addition to what became the final design, Stubbins and his associates studied at least six alternate proposals for the tower, with varying rooftop designs.^[28] Early plans also called for installing stilts underneath each corner.^[101] This plan was scrapped because the northwestern stilt would extend into St. Peter’s Lutheran Church, and the church wanted its sanctuary to be structurally separate.^[71][101] Plans for the tower were publicly disclosed on July 24, 1973.^[17][144] The plans called for a 910 ft (280 m)-tall tower called Citicorp Center, raised above the street level on 112 ft (34 m) stilts. The project would also include an eight-story office annex, three stories of retail, a landscaped public plaza, and a new church building.^[16][17][28] At the time, St. Peter’s old church building had been demolished,^[17] and First National City Bank had become known as Citibank, a subsidiary of Citicorp.^[143] St. Peter’s pastor Ralph E. Peterson described the project as «a very bold venture in an urban environment».^[150] Under Peterson’s insistence, the plans included a publicly accessible plaza with shopping.^[57][118] Early plans for the church also called for it to contain a cube design,^[66] though the church’s final design was announced in April 1974.^[72]

Groundbreaking ceremonies for the tower occurred during April 1974, though actual work did not commence for twelve months.^[18] The tower’s construction manager was supervised by Vivian Longo, who at the building’s completion in 1977 was twenty-five years old.^[48][151] Citicorp Center was one of the few large structures in Manhattan under construction during the mid-1970s.^[152] At the peak of construction, three thousand people were employed on the project, and 565 workers were on site simultaneously.^[18][39] The steelwork had been completed to the eighteenth floor by the end of 1975.^[18] The steel frame was topped out on October 7, 1976. At the time, officials predicted Citicorp Center would be the only major structure in New York City to be completed in 1977.^[24][153]

The cornerstone for the new St. Peter’s Church was laid on November 1, 1976, less than a month after the building had topped out.^[154] Citibank acquired two buildings at 148 and 152 East 53rd Street, immediately south of the new tower, the next month. The company did not intend to develop the sites of these buildings, but they contained topless bars, which Citibank officials perceived would decrease the value of the tower.^[155][156] The bank’s vice president for real estate management, Arthur E. Driscoll, had studied vacancy rates at fourteen nearby «prime office buildings» while Citicorp Center was being developed.^[157] The first tenants moved to the building in April 1977.^[40] By that August, the building was 96 percent rented.^[114] This high occupancy rate was in spite of the fact that space in the building was rented at a higher average rate than in other buildings in the neighborhood.^[39][40]

Early years[edit]

Opening[edit]

The building was dedicated on October 12, 1977.^[18][100] Stubbins gave an opening speech in which he described the building as a «skyscraper for the people».^[18][70] The project was the first to be completed under the purview of the Mayor’s Office of Midtown Planning since its establishment a decade prior.^[118] At the time of the building’s opening, the Market retail complex at the base was almost totally rented.^[146] Over three hundred retailers had submitted applications to operate within the space.^[114] The majority of the space was rented by household furnishings retailer Conran’s, which occupied 40,000 sq ft (3,700 m²),^[158] but some of the other retailers included restaurants serving cuisine of various countries.^[112] Citibank planned to occupy 600,000 sq ft (56,000 m²), or 26 stories, moving its offices to the building from five other addresses in Midtown.^[39][40] The remaining stories were occupied by a variety of firms, including those in law and accounting, as well as the Consulate-General of Japan and IBM.^[85]

At the time of Citicorp Center’s dedication, the final design features of St. Peter’s Church were being installed.^[159] St. Peter’s Church was dedicated on December 3, 1977,^[67][160] and the Nevelson Chapel was separately dedicated the same month.^[161] Initially, the tower’s slanted roof created an ice problem during winter, as snow and ice would slide down the roof onto the sidewalk.^[37] Furthermore, the shopping concourse was initially only lightly used and largely unknown to the public.^[162] The plaza on Lexington Avenue opened by July 1978.^[18] In the complex’s early years, St. Peter’s Church encountered fiscal deficits because of high utility costs, as well as inflation and lack of investment experience, even though the church earned money from renting out some of the other space it owned at Citicorp Center.^[163] By 1980, Citicorp counted 25,000 daily visitors to the shopping concourse, but some of the stores had already closed down because of a lack of patronage.^[117][164]

Engineering crisis of 1978[edit]

Due to material changes during construction, the building as initially completed was structurally unsound. LeMessurier’s original design for the chevron load braces used welded joints. To save money, Bethlehem Steel changed the plans in 1974 to use bolted joints, which was accepted by LeMessurier’s office but not known to the engineer himself.^[22] Furthermore, LeMessurier originally only needed to calculate wind loads from perpendicular winds under the building code; in typical buildings, loads from quartering winds at the corners would be less.^[22][165] In June 1978, after an inquiry from Princeton University engineering student Diane Hartley,^[166][167] LeMessurier recalculated the wind loads on the building with quartering winds.^[165] He found that quartering winds would significantly increase the load at the bolted joints.^[22] After conducting tests on the building’s structural safety,^[109] LeMessurier found that a wind capable of toppling Citicorp Center would occur every 55 years on average, or every 16 years with the tuned mass damper powered off.^[105]

LeMessurier proposed welding steel plates over the bolted joints, and Karl Koch Erecting was hired for the welding process.^[110] Starting in August 1978, construction crews installed the welded panels at night.^[94][110] Repairs were completed that October, after which LeMessurier claimed that a wind strong enough to topple the building would occur less often than every 700 years.^[94][168] The work was not publicized at the time, as it took place during the 1978 New York City newspaper strike and very few people were notified of the issue at the time.^[105][110] Since no structural failure occurred, the extent of the engineering crisis was only publicly revealed in a lengthy article in The New Yorker in 1995.^[94][169]

1980s and 1990s[edit]

As completed, Citicorp Center consisted of three separate ownership stakes in a condominium arrangement. One condominium was for the church while the other two were 61.55 and 32.85 percent ownership stakes in the office stories.^[170] In October 1987, Citicorp sold the 61.55 percent ownership stake (consisting of the 23rd through 59th floors), along with a one-third interest in its former 399 Park Avenue headquarters, to Dai-Ichi Mutual Life Insurance Company for $670 million. Citicorp used the profits from the sale to reduce its losses, which in the first half of 1987 totaled $2.32 billion and continued to own the remaining stories.^[171][172] At the time, Citicorp was also developing One Court Square across the East River in the Long Island City neighborhood of Queens.^[117][173] The new building in Queens was right above the Court Square–23rd Street subway station, one stop away from the Lexington Avenue–53rd Street station beneath Citicorp Center and 399 Park Avenue. The arrangement allowed Citicorp to split its offices between the buildings.^[173]

The Market shopping atrium fell into disrepair following Citicorp Center’s completion.^[174] In May 1995, Citicorp commenced a $15 million, eighteen-month renovation of the shopping concourse, designed by Gwathmey Siegel & Associates Architects.^[117][116] The brick pavers were replaced with terrazzo, new signs were installed outside each storefront, and circulation features such as the placement of escalators were rearranged.^{[117][174][175]} The shopping concourse was renamed the Shops at Citicorp Center and bookstore Barnes & Noble was named as the anchor tenant, taking 40,000 sq ft (3,700 m²).^[116]

21st century[edit]

By late 2000, Dai-Ichi’s broker Jones Lang LaSalle had placed the entire Citigroup Center for sale.^[176][177] Dai-Ichi arranged with Citigroup, its condominium partner, to jointly sell both condominium units.^[177] Richard and Eric D. Hadar, a father-and-son venture, bid $725 million for Dai-Ichi’s ownership stake in January 2001. For the purchase, Eric Hadar had arranged a $525 million first mortgage from Deutsche Bank and a $150 million mezzanine loan from the government of Singapore.^[176][178] The sale was delayed after Boston Properties offered to buy Dai-Ichi’s stake.^[179] Eric Hadar’s company, Allied Partners, along with Boston Properties, ultimately finalized their purchase of both condominium units that April.^[180][181] The building cost $755 million, including closing costs and taxes, and Citigroup relocated to 399 Park Avenue.^[117][182] One of the stilts was structurally reinforced following the September 11 attacks,^[103][104] and protective bollards were installed on the sidewalk.^[183]

Boston Properties bought Allied Partners’ stake in the Citigroup Center in 2006 for $100 million.^[184][185] The same year, Boston Properties began rebranding the building as «601 Lexington Avenue».^[186] A new Lexington Avenue lobby was constructed and the tower stories’ entrance was relocated from 53rd Street to Lexington Avenue.^[111][187] In addition, a ramp was installed on 53rd Street and a reception area was added to the northern entrance of St. Peter’s Church.^[117] The name change became effective in 2010.^{[117][188][189]} Boston Properties was also considering selling naming rights to the building.^[190] By 2013, Citigroup only occupied three stories at 601 Lexington Avenue.^[191] The next year, Boston Properties sold a 45 percent ownership stake in 601 Lexington Avenue, along with a proportional stake at the Atlantic Wharf Office Building and 100 Federal Street in Boston, to Norges Bank Investment Management for a combined $1.5 billion.^[192][193]

In mid-2016, the New York City Landmarks Preservation Commission (LPC) proposed protecting twelve buildings in East Midtown, including 601 Lexington Avenue, in advance of proposed changes to the area’s zoning.^[194] At the time, Boston Properties was contemplating renovations to the building; the company filed alteration plans for the plaza that July,^[59] and it was vacating the space in the office annex.^[195] On December 6, 2016, the LPC designated 601 Lexington Avenue as a city landmark.^{[3][196][197]} The designation made 601 Lexington Avenue the city’s youngest landmark at that time.^[196] The same month, Boston Properties announced plans to renovate the office annex, which would be rebranded 159 East 53rd Street.^[198][199] Shortly afterward, in March 2017, Gensler revealed its design for a refurbished entry plaza and a new atrium space.^[200][201] That June, work on the plaza commenced and the original fountain was demolished, despite being part of the landmark designation.^[64] All of the space at the 159 East 53rd Street annex was leased to NYU Langone Health in 2018.^[202][203] Following the completion of the renovation, in late 2019, Anna Castellani signed a lease to operate a 10,000 sq ft (930 m²) food hall at the base of 601 Lexington Avenue.^[204][205] In October 2019, London-based company etc.venues signed a lease to operate a 30,000 sq ft (2,800 m²) conference center on the 14th floor.^[206]

In December 2021, Boston Properties and Norges Bank Investment Management refinanced 601 Lexington Avenue with a $1 billion, 10-year fixed rate mortgage from a consortium of four banks.^[207][208] At the time, the building’s office space was 96.3 percent occupied, and the tenants largely included financial firms and law offices.^[209] With about 326,000 square feet (30,300 m²) of space, the Blackstone Group was one of the building’s largest tenants in 2022.^[210][211] Other large tenants included Citibank, Kirkland & Ellis, and Freshfields Bruckhaus Deringer.^[209]

Impact[edit]

Critical reception[edit]

During Citicorp Center’s construction, the building received large media attention, it had been one of three new office buildings in Manhattan whose plans were approved in 1974.^[85] After the design was announced, Ada Louise Huxtable criticized the design in The New York Times, saying the tower «has neither romanticism nor structural rationalism but, instead, appears to have been painstakingly invented with a tortured logic through a series of pragmatic and esthetic compromises».^[24][212] As the building was being completed, Huxtable took a less harsh tone to the building, saying that it contained a «clear desire for design quality» despite the drawbacks of the form and roof.^[85][213] A writer for the New York Daily News said: «Put this in Cleveland and it would be the eighth wonder of the world. In New York people hardly look up.»^[214] Suzanne Stephens wrote for New York magazine that the building was «little more than a modern Fifties high rise in drag»,^[24][97] considering the rooftop and base to be wasteful with space.^[97]

After the building’s completion, it received mixed reception. Paul Goldberger wrote for The New York Times that the roof «is a lot more fun to look at than almost any building top in years», with a reflective facade and a varied form, but the overall design «stops short of doing anything really radical».^[100] Jack Egan wrote similarly for The Washington Post, saying that the building had distinctive design features but did not appeal to either nostalgia or novel innovation.^[40] Huxtable regarded the plaza as an architectural success but observed in January 1978 that very few people used it.^[162] The interior space was described by August Heckscher II, a former New York City parks commissioner, as «an amenity in which we can all rejoice».^{[76][117][215]} Nevertheless, Heckscher believed the atrium’s silver cladding and light fixtures to be «cold» and suggestive of the indoors,^[76][215] and Stephens found the space to be «claustrophobic» and a «stratified success» whose benefits did not transcend class boundaries.^[76][216]

Other critics described Citicorp Center in a largely positive light. John Tauranac described the tower as the «most dramatic new skyscraper» in New York City since the completion of 30 Rockefeller Plaza several decades prior.^[85][217] Architectural writer Robert A. M. Stern wrote that Citicorp Center was the summation of a «unique architectural and urbanistic character that made Fifty-third Street at once an enclave within midtown and a microcosm of midtown itself».^[13] William H. Whyte particularly praised the structure as juxtaposing «a lot of elements at the right moment», particularly the exterior plaza and sidewalk.^[7] The building was also praised by publications outside the New York City area.^[85] The Baltimore Sun described the building as containing «simplicity […] that goes beyond sophistication»,^[26] while The Observer of London called it «a unique contribution to the East Side skyline».^[85]

Awards and use as icon[edit]

Upon Citicorp Center’s completion, it received several architectural awards. In 1978, the City Club of New York gave the building a Bard Award, which recognized «excellence in architecture and urban design».^[218] The same year, it received the American Institute of Steel Construction’s Architectural Award of Excellence.^[20][85] The American Institute of Architects gave the building an Honor Award in 1979.^{[2][219][220]} Furthermore, Hugh Stubbins and Associates received the AIA’s R.S. Reynolds Memorial Award in 1981 for its use of aluminum in the design of Citicorp Center.^{[220][221][222]}

The sloped roof of the building has been used for branding; for instance, it is included on the label of Chock full o’Nuts coffee.^[223] The roof was also depicted in the Manhattan Mini Storage logo, where the top left corner of the first letter «M» was sloped like the Citigroup Center.^[224] Additionally, since 2014, the New York Mets have sometimes used a logo that has included the Citigroup Center, as the bank also sponsors the Mets’ home stadium, Citi Field.^[225]

See also[edit]

• List of New York City Designated Landmarks in Manhattan from 14th to 59th Streets
• List of tallest buildings in New York City
• List of tallest buildings in the United States
• List of tallest freestanding steel structures

References[edit]

Notes[edit]

Citations[edit]

Sources[edit]

• «At the core of the Apple» (PDF). Progressive Architecture. Vol. 59, no. 12. December 1978.
• «At New York’s Citicorp Center, a structure of masterly invention underlies the urbane face of a skyscraper in the grand manner» (PDF). Architectural Record. Vol. 159, no. E3. August 1978. pp. 66–71.
• Hellman, Peter (February 24, 1974). «How They Assembled the Most Expensive Block in New York’s History». New York. Vol. 31. pp. 31–37.
• «Legs centered under each face carry diagonally braced tower» (PDF). Engineering News-Record. June 24, 1976. pp. 68–70.
• Morgenstern, Joseph (May 25, 1995). «The Fifty-Nine-Story Crisis». The New Yorker. pp. 45–53.
• Postal, Matthew A. (December 6, 2016). «Citicorp Center» (PDF). New York City Landmarks Preservation Commission.
• Schmertz, Mildred F. (June 1978). «Citicorp Center: If You Don’t Like the Crown Look At Its Base» (PDF). Architectural Record. Vol. 163, no. 7.
• Stern, Robert A. M.; Mellins, Thomas; Fishman, David (1995). New York 1960: Architecture and Urbanism Between the Second World War and the Bicentennial. New York: Monacelli Press. pp. 490–496. ISBN 1-885254-02-4. OCLC 32159240.

External links[edit]

• Official website

The Citigroup Center (formerly Citicorp Center and also known by its address, 601 Lexington Avenue) is an office skyscraper in the Midtown Manhattan neighborhood of New York City. Built in 1977 to house the headquarters of Citibank, it is 915 ft (279 m) tall and has 59 floors with 1.3×10⁶ sq ft (120,000 m²) of office space. The building was designed by architect Hugh Stubbins, associate architect Emery Roth & Sons, and structural engineer William LeMessurier.

601 Lexington Avenue takes up much of a city block bounded clockwise from west by Lexington Avenue, 54th Street, Third Avenue, and 53rd Street. The building has a 45° angled top with a base on four stilts, as well as a six-story office annex to the east. The tower overhangs St. Peter’s Evangelical Lutheran Church at Lexington Avenue and 54th Street, a standalone granite structure designed simultaneously by Stubbins. Also at the base is a sunken plaza, a shopping concourse, and entrances to the church and the New York City Subway’s Lexington Avenue/51st Street station. The tower stories are supported by stacked load-bearing braces in the form of inverted chevrons. Upon Citicorp Center’s completion, it received mixed reviews from architectural critics, but also several architectural accolades.

Land acquisition for what became Citicorp Center commenced in 1968 and took five years. St. Peter’s Church sold its plot on the condition that a new church building be constructed at the base of the tower. The design was announced in July 1973 and the structure was completed in October 1977. During the Citicorp Center engineering crisis less than a year after the building’s completion, emergency repairs were made after the tower was discovered to be vulnerable to collapse due to wind. The building was acquired by Boston Properties and Citicorp Center was renamed 601 Lexington Avenue in the 2000s. The New York City Landmarks Preservation Commission designated 601 Lexington Avenue as a city landmark in 2016. Over the years, the atrium, plaza, and other public spaces have been renovated.

Site[edit]

The building is in the Midtown Manhattan neighborhood of New York City. It takes up the majority of a city block bounded by Lexington Avenue to the west, 54th Street to the north, Third Avenue to the east, and 53rd Street to the south. The land lot covers 70,572 sq ft (6,556.4 m²) with a frontage of 200 ft (61 m) on Lexington Avenue and a depth of 325 ft (99 m).^[4] The only other building on the block is 880 Third Avenue, an 18-story structure at 53rd Street and Third Avenue.^[4][5] Other nearby buildings include 599 Lexington Avenue to the south, 100 East 53rd Street and the Seagram Building to the southwest, 399 Park Avenue to the west, the Central Synagogue to the northwest, and the Lipstick Building to the east.^[4] The New York City Subway’s Lexington Avenue/51st Street station (served by the 6, <6>​​, E, and ​M trains) is directly underneath 601 Lexington Avenue.^[6]

Custom street furniture including newsstands, flagpoles, and streetlight pylons was designed for the sidewalks around 601 Lexington Avenue and installed in 1978.^[7][8] New Jersey-based company Designetics designed pylons with a cruciform cross-section and street lamps at the top. Seven pylons are placed in the middle of the block. Three custom pylons, at the northwest, northeast, and southwest corners of the block,^[a] include pedestrian and vehicular traffic lights. The pylons were initially designed with a «glossy black finish» that contrasted with the tower’s aluminum facade;^[7][8][9] by 2016, they had been painted gray.^[7] The New Yorker described the pylons in 2017 as «sculptural towers worthy of Brancusi».^[10]

Thirty-one structures were acquired and demolished to make way for the development.^[5][11] Most of these were brownstone houses;^[12] some contained commercial spaces, ranging from small shops to the upscale Cafe Chauveron.^[12][13] The site also included the Medical Chambers on 54th Street, which was owned by forty doctors.^[12][14] The only remaining previous occupant of the site is St. Peter’s Evangelical Lutheran Church, whose sanctuary at Lexington Avenue and 54th Street, on the northwest corner of the block, was rebuilt when the Citigroup Center was developed.^[5][11]

Architecture[edit]

601 Lexington Avenue, also known as the Citigroup Center and Citicorp Center,^[3][15] was designed by architect Hugh Stubbins as the headquarters for First National City Bank (later Citibank), along with associate architect Emery Roth & Sons.^[15][16][17] Of the principals at Hugh A. Stubbins & Associates, architect Peter Woytuk was most involved in design, while project manager W. Easley Hammer oversaw construction.^[18][19] In addition, Edward Larrabee Barnes was the consulting architect,^[2][17][19] and LeMessurier Associates and James Ruderman were the structural engineers.^[16][20] The general contractor was HRH Construction Corporation^[18][20][21] and the steel contractor was Bethlehem Steel.^[20][22] Various other contractors were hired to supply material for the building.^[23]

Form and facade[edit]

The Citigroup Center is 59 stories high, with its roof about 915 ft (279 m) above ground level.^[2][3][b] Excluding unused floor numbers at the base, it contains 46 office stories.^[26][27] At the time of completion, Citicorp Center was the seventh-tallest building in the world.^[24][25] In addition to the primary 59-story tower, there is an annex at 159 East 53rd Street with six^[25][28] or seven stories.^[29] It extends east to Third Avenue and includes part of the building’s shopping concourse.^[25][28] The facades of the tower and its annex are designed similarly.^[30]

The facade is made of anodized aluminum and reflective glass panels.^[30][31][32] Each facade segment measures 12 by 9 ft (3.7 by 2.7 m) and consists of both glass panes and aluminum plates.^[33] As an energy-saving measure, the glass windows were manufactured as two panes, the inner pane of which was coated with chrome plating.^[7][31][32] The windows on each floor are separated by flush aluminum spandrels.^[34] The spandrels were manufactured by Flour City Architectural Metals, a firm based in Glen Cove, New York.^[30][35] The aluminum is silver-colored, like that on the Pepsi-Cola Building and One Chase Manhattan Plaza, because Stubbins thought a dark color would not allow observers to «see the shade and shadow».^[30] The metal panels were fitted with double the amount of insulation considered normal at the time of construction. The aluminum was polished to reflect heat from sunlight.^[7][31][32]

Roof[edit]

The triangular roof of 601 Lexington Avenue rises 160 ft (49 m) above the top story and faces south, sloping at a 45-degree angle.^{[25][28][36][c]} Before the official plans were announced in 1973, the architects had intended the roof to be terraces for apartments,^[38][39] which would have faced westward.^[30][39] There would have been about 100 apartments,^[40][41] but the New York City Department of City Planning would not approve a zoning change to permit that use.^[27][30][41] The architects then rotated the roof southward^[39][42] to accommodate flat-plate solar collectors that could produce hot water, which would be used to dehumidify air and reduce cooling energy.^[3][43] Starting in February 1975, engineers from the Massachusetts Institute of Technology conducted a twelve-month feasibility study for the installation of such a system.^[28][44][45] Afterward, the system was scrapped, either because of the low savings,^[46][47][48] refinement of mechanical systems,^[32] or disputes with the supplier.^[7]

Even after the solar-collector plans were scrapped, the design was kept; Stubbins wrote that the roof «relieves the uniformity of flat-topped towers proliferating in the center of the city».^[49][50] This made Citicorp Center the first postmodern skyscraper whose roof was designed solely for decorative purposes.^[36][51] The roof was also fitted with solar panels in 1983, when Consolidated Edison and Citibank sponsored a four-year solar panel test.^[7][52]

Exterior spaces[edit]

Plaza[edit]

A large plaza 12 ft (3.7 m) beneath street level was built along with Citicorp Center and designed by landscape architect Hideo Sasaki.^[53] The plaza was included under the 1961 Zoning Resolution,^[53] which allowed New York City developers a zoning «bonus» for including open space in front of their buildings.^[54] While many developers took advantage of the «bonus», the New York City Planning Commission found in 1975 that many of these plazas ranged from «bleak, forlorn places» to «forbidding and downright hostile».^[55][56] In response, the City Planning Commission’s Urban Design Group had been formed in 1967 to determine how to improve plaza designs,^[53][57] influencing the commission’s decision to modify the zoning laws in 1975.^[53][56] The design of 601 Lexington Avenue’s plaza was finalized in 1973 before these rule changes were enacted.^[53] However, the plaza included many of the same features that were proposed in the rule change, such as an outdoor plaza, a covered pedestrian area, and an arcade running through the city block.^[53][58]

The plaza has an area of 6,000 sq ft (560 m²).^[59] Its presence allowed the tower to be designed with a maximum floor area ratio of 18:1, higher than the 15:1 ratio specified for the area.^[27] The plaza is accessed by a set of stairs extending northeast from the corner of Lexington Avenue and 53rd Street.^[53][60] On the south side of the plaza is an entrance to the Lexington Avenue/51st Street subway station.^[61][62] This subway entrance replaces two staircases from the street, which were demolished to make way for Citicorp Center.^[53] The north side of the plaza contains the entrance to St. Peter’s Church and the east side contains an entrance to the lower lobby.^[63] During the plaza’s construction, the developers collaborated with the numerous public agencies with a stake in the project, including the Metropolitan Transportation Authority, which operated the subway station.^[34]

The plaza, interior shopping concourse, and sidewalks all initially contained brown brick floor pavers. There was also originally a fountain at the center of the plaza, which was designed to conceal noise from the environs, similar to the fountain at nearby Paley Park.^[63] 601 Lexington Avenue’s fountain was demolished in 2017.^[64]

St. Peter’s Lutheran Church[edit]

St. Peter’s Lutheran Church is on the northwest corner of the Citigroup Center site, at 619 Lexington Avenue and 54th Street.^[65] The exterior was designed by Stubbins and Hammer, while the interior was furnished by Vignelli Associates.^[8][66][67] The church occupies the same site as its old building. The congregation permitted Citicorp to erect the skyscraper only if a new church was built at the same location, structurally unconnected to the tower. Andrew Alpern and Seymour Durst characterized the agreement as «ecumenically joining God and mammon to the benefit of both».^[13][68] Additionally, at least 63 percent of the church had to contain «nothing built above it».^[67][69] According to Stubbins, the lack of structural connections would give the church a «breathing space» of its own.^[70]

The structure is within 601 Lexington Avenue’s sunken plaza, rising about 60 ft (18 m) above ground^[71] or 85 ft (26 m) in total.^[8][66][67] It contains a facade of brown Caledonia granite with ashlar.^{[66][67][71][29]} The roof is clad in copper coated with lead. The materials were meant to establish a distinct identity for the church while also associating it with 601 Lexington Avenue’s tower.^[8][67] At the top of the church, a skylight bisects the church building diagonally from southwest to northeast, allowing passersby to look into the church building.^[66][71][29] A window facing the corner of Lexington Avenue and 54th Street overlooks the pipe organ inside.^[67] Stubbins had intended the structure’s shape to resemble a pair of hands «held up in prayer with light coming between them».^[72] Arnaldo Pomodoro designed a bronze cross for the exterior, which was installed in 1982 and measures 8 ft (2.4 m) tall by 6 ft (1.8 m) wide.^[73]

The main sanctuary is adjacent to the lower plaza,^[63][74] about 5 ft (1.5 m) beneath the plaza.^[63] It has a capacity of 850 seats; the center set of pews is designed to be movable so the space could host events when needed.^[8] There was also a black-box theater, a library, kitchen, daycare center, clergy offices, dressing rooms, choir rooms, and lecture and community rooms.^[72] Upon the church’s completion, there was a two-manual, two-pedal organ with 2,175 pipes.^[75] Inside the church is the Nevelson Chapel (also known as the Chapel of the Good Shepherd), which was donated by parishioner Erol Beker^[76] and designed by sculptor Louise Nevelson.^[74][77] The 24-seat chapel^[78] measures 21 by 24 ft (6.4 by 7.3 m)^[76] and contains sculptural elements on the wall including reliefs, altarpieces, and columns.^[79][80][81] It was renovated in the 1980s,^[78] and it was restored from 2018 to 2019 by Kostow Greenwood Architects^[82][83] as part of a $5.75 million renovation partly funded by Nevelson’s Pace Gallery.^[83][84] The space was described by David W. Dunlap in 2004 as the city’s «most architecturally successful postwar sanctuary».^[85][86]

The church’s basement theater is used by the York Theatre.^[87][88] St. Peter’s Church also hosts a jazz ministry created by the Rev. John Garcia Gensel, who in 1965 became the Minister to the Jazz Community.^[89][90] The jazz ministry has sponsored several programs over the years,^[67] such as free jazz performances at the base of Citicorp Center.^[91] The church has hosted memorials or funerals for jazz musicians such as Miles Davis, Dizzy Gillespie, and Thelonious Monk.^[67] In 2021, the church was seriously damaged after a broken water main flooded its space.^[92][93]

Structural features[edit]

The tower stories are of «trussed tube» construction.^[94][95] Each of the tower stories measures 157 by 157 ft (48 by 48 m),^[20][96] or 24,600 sq ft (2,290 m²) total.^[97] Within the tower stories, the elevators and emergency stairs are embedded in a service core at the center of each story.^[98] The core is about 68 by 68 ft (21 by 21 m), while the floor space around the core is just less than 45 ft (14 m) wide.^[96] Overall, 601 Lexington Avenue contains 24,000 short tons (21,000 long tons; 22,000 t) of steel, forty percent the amount used in the Empire State Building.^[94][99]

Stilts[edit]

The tower is supported by four stilts measuring approximately 112 ft (34 m) high with a cross section of 24 by 24 ft (7.3 by 7.3 m).^{[16][28][60][d]} The stilts are underneath the centers of the tower’s outer edges, cantilevering 72 ft (22 m) outward from the core.^{[22][25][51][61]} According to Stanley Goldstein of LeMessurier’s New York City office, stilts at the center of each edge were able to withstand forces from «quartering winds» from the corners, compared to stilts that were placed at the corner. Additionally, the placement of the stilts allowed a smaller foundation than in a conventional building of similar size.^[96]

Each of the individual stilts is composed of four vertical beams, of which the outer pairs are much heavier than the inner pairs.^{[94][101][102]} This design makes each stilt similar to a vertical K-truss, which prevents the stilt from buckling.^[102] Although the stilts could have theoretically been thinner, they were enlarged to give the tower a more stable appearance. Inside the stilts are emergency stairs and mechanical ducts.^[94][101] In 2002, following the September 11 attacks the previous year, one of the stilts was reinforced with blast-resistant shields of steel and copper as well as steel bracing.^[103][104] There is also an octagonal elevator core in the middle of the building,^{[30][51][102]} which measures 63 by 72 ft (19 by 22 m)^[102] and carries the structural loads from gravity.^[101] Unlike on the upper stories, the elevator core contains only elevators, as the emergency staircases are within the stilts.^[102]

Chevrons[edit]

Above the stilts are stacked load-bearing braces in the form of inverted chevrons, which are designed to distribute tension loads from the upper stories that are created by wind.^[24][105] On each side, there are six chevrons, each of which absorb wind loads at intervals of eight stories.^{[22][51][106]} The wind loads from each eight-story tier are transferred into the center of the frame, where 60 in-wide (150 cm) «mast column transports» extend the full height of the tower.^[96][106] The mast columns are 30 in (760 mm) deep at the base, tapering to 18 ft (5.5 m) at the 40th floor. The diagonal beams that form each chevron are 14 in (360 mm) deep and connect to structural spandrels at the top of each eight-story tier, which are 36 in (910 mm) deep.^[96] The tops of each eight-story tier (where the diagonal beams meet the corner) do not contain vertical columns, thus preventing wind loads from accumulating at the tower’s corners.^[29]

The ninth story, the lowest level above the stilts, contains a trussed frame similar in design to a cantilever bridge, where the wind loads are transferred downward into the stilts.^[106][107] This story is used as a mechanical room.^[107]

The chevrons are not visible from the exterior but can be seen from the offices inside,^[24][108] in contrast to structures such as Chicago’s John Hancock Center.^[24][34][39] After Citicorp Center’s completion, W. Easley Hammer reflected that he thought it was a mistake to conceal the chevrons,^[24] while LeMessurier said that Stubbins had rejected his idea for exposed chevrons.^[22][94] The chevrons were bolted to each other with over two hundred joints; as built, these posed a serious structural danger, leading to the Citicorp Center engineering crisis.^[94][109] As a result, 2 in-thick (5.1 cm) welded steel plates were installed over each joint in 1978.^[94][110]

Interior[edit]

The tower contains approximately 1.3×10⁶ sq ft (120,000 m²) of rentable space. The office annex to the east contains about 270,000 sq ft (25,000 m²) of space.^[24] According to the Department of City Planning, the building has a gross floor area of 1,654,020 sq ft (153,663 m²),^[4] while according to The Skyscraper Center, the building has 1,578,883 sq ft (146,683.0 m²).

Base[edit]

601 Lexington Avenue’s main entrance lobby is at the middle of the Lexington Avenue frontage, across a footbridge that provides entrance to St. Peter’s Church. The main entrance consists of a double-height glass box with steel ribs, which is 70 ft (21 m) long. The lobby was constructed as part of a 2010 renovation.^[111]

There is a three-story shopping concourse at the base of the stilts, originally called the Market.^[48][112] The lowest level, corresponding to the lower lobby, includes a planted atrium measuring 85 ft (26 m) high, with a skylight measuring 90 by 100 ft (27 by 30 m).^[76][113] The corner of Third Avenue and 54th Street contained an entrance to the lowest level of the shopping concourse, while on 54th Street was an entrance to the second level.^[113] The storefronts were designed to blend in with the plaza and street, with similar floor surfaces and transparent exterior walls.^[114] Overall, the stores were intended as a commitment to the city, a corporate symbol, and a tourist attraction, according to one of Citicorp’s vice presidents, Arthur E. Driscoll.^[24][112] The bank presented a model train exhibition in the space each December from 1987 to 2009.^[115] The shopping concourse was renamed The Shops at Citicorp Center in 1995,^[116] and it is known as The Atrium as of 2016.^[117]

Mechanical features[edit]

In the office stories, the elevators and stairs are clustered in a central core.^[118] The building contains 20 double-deck elevators,^[119][120] which Otis Worldwide constructed for $7 million.^[119][121] Although each of the upper or lower decks serves only odd or even floors, visitors can travel between odd and even floors using escalators.^[38] Each of the double-deck elevators consists of two standard elevator cabs that operate simultaneously in one shaft.^[119][120] The double-deck elevators cost 25 percent more than standard elevators but allowed a 24 percent reduction in the floor area taken up by elevators;^[122] namely, twenty-six single-deck elevator shafts would have been required otherwise.^[97] 601 Lexington Avenue’s double-deck elevators were likely the first to be installed in New York City since 1932, when the Cities Service Building was completed.^[7][28] In total, 601 Lexington Avenue has 38 elevators.

Citicorp Center was also designed with other mechanical systems. At its completion, each tenant received mail from a «supermail» system. Incoming mail was sorted in the basement and transferred via lifts to each floor, where the mail was transported manually to fixed bins.^[123] The building also contained 2,500 sensors to monitor the mechanical systems, such as HVAC, lighting, electrical, sprinkler, life-safety, security, and elevator systems.^[120] The sloped roof includes mechanical equipment.^[32]

At the building’s completion, it was intended to be energy-efficient.^{[16][31][120]} The building’s water supply consisted of only cold water.^[32] Heat from the building’s mechanical systems was recirculated to warm the water supply and heat the office spaces. The office spaces were cooled with outside air wherever it was practical.^[31] The fluorescent light bars in the ceiling, manufactured by Joseph Loring & Associates, were fitted with glass shields to spread the artificial light more efficiently, thereby requiring fewer lighting fixtures.^[31][120] Even though the rooftop solar collectors were not installed, the other features allowed the building to use 42 percent less energy compared to a regular office building of the same size.^[100] However, during the summer, the building used a conventional air-conditioning system, which offset the savings from the heat-deflecting facade.^[97]

Citicorp Center was the city’s first skyscraper to feature a tuned mass damper (TMD).^{[24][29][108]} Located within the rooftop mechanical space, the TMD is designed to counteract swaying motions due to wind and reduces wind-related movement by up to fifty percent.^{[94][124][125]} The equipment weighs 400 short tons (360 long tons; 360 t) and includes a concrete block measuring 30 by 30 by 6 ft (9.1 by 9.1 by 1.8 m).^[20][24][39] The concrete block sits on a pool of oil within a steel plate and has two spring mechanisms, one each to counteract north-south and east-west movement. The equipment cost $1 million to install. By comparison, it would have cost $5 million to add mass to reduce the tower’s movement,^[108] namely 2,800 short tons (2,500 long tons; 2,500 t) of additional steel.^[126]

History[edit]

National City Bank was founded in 1812^[127] and, for over a century, had its headquarters in the Financial District of Lower Manhattan.^[5] The company was headquartered at 52 Wall Street^[128] until 1908, when it moved to 55 Wall Street.^[129][130] After National City Bank and the Farmers’ Loan and Trust Company merged in 1929,^[131] these companies expanded into a new structure at 20 Exchange Place, completed in 1931.^[132][133] City Bank Farmers Trust moved to 399 Park Avenue, one block west of the present Citigroup Center, in 1961.^[134]

On the northwestern corner of the Citigroup site was St. Peter’s Lutheran Church, which had been founded in 1862 as a German-speaking congregation.^[5][e] The church’s previous structure, a Gothic building designed by John G. Michel and P. Brandner,^[135] was completed in 1905.^[5][11][136] The congregation’s previous sanctuary at Lexington Avenue and 46th Street, which it had occupied since 1871, had been demolished in 1902 for the construction of Grand Central Terminal.^[5][11] The congregation, which at its peak had membership of over one thousand, had decreased to below 300 by the 1960s, prompting the congregation to consider relocating to near the United Nations headquarters.^[5][11][13]

Development[edit]

Site acquisition[edit]

The lots on the St. Peter’s block were acquired secretively in five and a half years starting around 1968.^[5][137] The acquisition was headed by brokers Donald Schnabel and Charles McArthur of Julien J. Studley Inc.^[13][138] The brokers believed that a large, continuous land lot would be worth more than the sum of each lot’s individual worth, though the firm had not yet secured a client for which it was purchasing the lots.^[138] Furthermore, St. Peter’s Church’s membership was once again increasing and they were loath to part with their property.^[11] Subsequently, a Studley broker formed a company called Lexman, which then approached First National City Bank to determine their interest in the St. Peter’s block, one block east of their headquarters at the time.^[5][139] Lexman gradually acquired the other lots on the block.^[137] Former Citicorp Chairman Walter B. Wriston reportedly decided to acquire several other low- and mid-rise buildings in the area, supposedly to buy out massage parlors and mom-and-pop stores in Midtown.^[140]

The firm again negotiated with St. Peter’s congregation in late 1969 after some lots had been acquired.^[18] John White, president of James D. Landauer Associates consultants, proposed that the new structure on the site be a condominium development; i.e. the church would have a partial ownership stake in the new development.^[141][142] In February 1970, the congregation signed a «letter of intent» to sell its building, as well as the air rights above the church,^[141][142] to First National City Bank.^[143][144] In exchange, the congregation received $9 million and was named as a condominium partner in the tower’s development. Subtracting the $5 million cost of the new church building, the congregation netted a $4 million profit.^{[141][143][145]}

By January 1971, Hugh Stubbins & Associates were hired to develop plans for a large building on the city block, and St. Peter’s Church had hired Edward Larrabee Barnes to represent its design interests.^[14] The Stubbins firm was then relatively inexperienced in designing high-rise buildings.^[13] The New York Times characterized the site as an «annex» to First National City Bank’s main building at 399 Park Avenue.^[14][141] The congregation of St. Peter’s Church voted in May 1971 to approve the sale and construct a new structure on the same site,^[146][147] and they relocated in early 1973 to a temporary location at the Central Presbyterian Church.^[148] By July 1973, land acquisition was virtually complete,^[149] although the last parcel was not acquired until November 1975, when the lot at 884 Third Avenue was purchased.^[141] The acquisition cost was $40 million, making the site the most expensive city block on earth.^[19][144] The only lot not acquired was 880 Third Avenue, which had been completed in 1965, and which the brokers considered too new to be demolished.^[13]

Construction[edit]

In addition to what became the final design, Stubbins and his associates studied at least six alternate proposals for the tower, with varying rooftop designs.^[28] Early plans also called for installing stilts underneath each corner.^[101] This plan was scrapped because the northwestern stilt would extend into St. Peter’s Lutheran Church, and the church wanted its sanctuary to be structurally separate.^[71][101] Plans for the tower were publicly disclosed on July 24, 1973.^[17][144] The plans called for a 910 ft (280 m)-tall tower called Citicorp Center, raised above the street level on 112 ft (34 m) stilts. The project would also include an eight-story office annex, three stories of retail, a landscaped public plaza, and a new church building.^[16][17][28] At the time, St. Peter’s old church building had been demolished,^[17] and First National City Bank had become known as Citibank, a subsidiary of Citicorp.^[143] St. Peter’s pastor Ralph E. Peterson described the project as «a very bold venture in an urban environment».^[150] Under Peterson’s insistence, the plans included a publicly accessible plaza with shopping.^[57][118] Early plans for the church also called for it to contain a cube design,^[66] though the church’s final design was announced in April 1974.^[72]

Groundbreaking ceremonies for the tower occurred during April 1974, though actual work did not commence for twelve months.^[18] The tower’s construction manager was supervised by Vivian Longo, who at the building’s completion in 1977 was twenty-five years old.^[48][151] Citicorp Center was one of the few large structures in Manhattan under construction during the mid-1970s.^[152] At the peak of construction, three thousand people were employed on the project, and 565 workers were on site simultaneously.^[18][39] The steelwork had been completed to the eighteenth floor by the end of 1975.^[18] The steel frame was topped out on October 7, 1976. At the time, officials predicted Citicorp Center would be the only major structure in New York City to be completed in 1977.^[24][153]

The cornerstone for the new St. Peter’s Church was laid on November 1, 1976, less than a month after the building had topped out.^[154] Citibank acquired two buildings at 148 and 152 East 53rd Street, immediately south of the new tower, the next month. The company did not intend to develop the sites of these buildings, but they contained topless bars, which Citibank officials perceived would decrease the value of the tower.^[155][156] The bank’s vice president for real estate management, Arthur E. Driscoll, had studied vacancy rates at fourteen nearby «prime office buildings» while Citicorp Center was being developed.^[157] The first tenants moved to the building in April 1977.^[40] By that August, the building was 96 percent rented.^[114] This high occupancy rate was in spite of the fact that space in the building was rented at a higher average rate than in other buildings in the neighborhood.^[39][40]

Early years[edit]

Opening[edit]

The building was dedicated on October 12, 1977.^[18][100] Stubbins gave an opening speech in which he described the building as a «skyscraper for the people».^[18][70] The project was the first to be completed under the purview of the Mayor’s Office of Midtown Planning since its establishment a decade prior.^[118] At the time of the building’s opening, the Market retail complex at the base was almost totally rented.^[146] Over three hundred retailers had submitted applications to operate within the space.^[114] The majority of the space was rented by household furnishings retailer Conran’s, which occupied 40,000 sq ft (3,700 m²),^[158] but some of the other retailers included restaurants serving cuisine of various countries.^[112] Citibank planned to occupy 600,000 sq ft (56,000 m²), or 26 stories, moving its offices to the building from five other addresses in Midtown.^[39][40] The remaining stories were occupied by a variety of firms, including those in law and accounting, as well as the Consulate-General of Japan and IBM.^[85]

At the time of Citicorp Center’s dedication, the final design features of St. Peter’s Church were being installed.^[159] St. Peter’s Church was dedicated on December 3, 1977,^[67][160] and the Nevelson Chapel was separately dedicated the same month.^[161] Initially, the tower’s slanted roof created an ice problem during winter, as snow and ice would slide down the roof onto the sidewalk.^[37] Furthermore, the shopping concourse was initially only lightly used and largely unknown to the public.^[162] The plaza on Lexington Avenue opened by July 1978.^[18] In the complex’s early years, St. Peter’s Church encountered fiscal deficits because of high utility costs, as well as inflation and lack of investment experience, even though the church earned money from renting out some of the other space it owned at Citicorp Center.^[163] By 1980, Citicorp counted 25,000 daily visitors to the shopping concourse, but some of the stores had already closed down because of a lack of patronage.^[117][164]

Engineering crisis of 1978[edit]

Due to material changes during construction, the building as initially completed was structurally unsound. LeMessurier’s original design for the chevron load braces used welded joints. To save money, Bethlehem Steel changed the plans in 1974 to use bolted joints, which was accepted by LeMessurier’s office but not known to the engineer himself.^[22] Furthermore, LeMessurier originally only needed to calculate wind loads from perpendicular winds under the building code; in typical buildings, loads from quartering winds at the corners would be less.^[22][165] In June 1978, after an inquiry from Princeton University engineering student Diane Hartley,^[166][167] LeMessurier recalculated the wind loads on the building with quartering winds.^[165] He found that quartering winds would significantly increase the load at the bolted joints.^[22] After conducting tests on the building’s structural safety,^[109] LeMessurier found that a wind capable of toppling Citicorp Center would occur every 55 years on average, or every 16 years with the tuned mass damper powered off.^[105]

LeMessurier proposed welding steel plates over the bolted joints, and Karl Koch Erecting was hired for the welding process.^[110] Starting in August 1978, construction crews installed the welded panels at night.^[94][110] Repairs were completed that October, after which LeMessurier claimed that a wind strong enough to topple the building would occur less often than every 700 years.^[94][168] The work was not publicized at the time, as it took place during the 1978 New York City newspaper strike and very few people were notified of the issue at the time.^[105][110] Since no structural failure occurred, the extent of the engineering crisis was only publicly revealed in a lengthy article in The New Yorker in 1995.^[94][169]

1980s and 1990s[edit]

As completed, Citicorp Center consisted of three separate ownership stakes in a condominium arrangement. One condominium was for the church while the other two were 61.55 and 32.85 percent ownership stakes in the office stories.^[170] In October 1987, Citicorp sold the 61.55 percent ownership stake (consisting of the 23rd through 59th floors), along with a one-third interest in its former 399 Park Avenue headquarters, to Dai-Ichi Mutual Life Insurance Company for $670 million. Citicorp used the profits from the sale to reduce its losses, which in the first half of 1987 totaled $2.32 billion and continued to own the remaining stories.^[171][172] At the time, Citicorp was also developing One Court Square across the East River in the Long Island City neighborhood of Queens.^[117][173] The new building in Queens was right above the Court Square–23rd Street subway station, one stop away from the Lexington Avenue–53rd Street station beneath Citicorp Center and 399 Park Avenue. The arrangement allowed Citicorp to split its offices between the buildings.^[173]

The Market shopping atrium fell into disrepair following Citicorp Center’s completion.^[174] In May 1995, Citicorp commenced a $15 million, eighteen-month renovation of the shopping concourse, designed by Gwathmey Siegel & Associates Architects.^[117][116] The brick pavers were replaced with terrazzo, new signs were installed outside each storefront, and circulation features such as the placement of escalators were rearranged.^{[117][174][175]} The shopping concourse was renamed the Shops at Citicorp Center and bookstore Barnes & Noble was named as the anchor tenant, taking 40,000 sq ft (3,700 m²).^[116]

21st century[edit]

By late 2000, Dai-Ichi’s broker Jones Lang LaSalle had placed the entire Citigroup Center for sale.^[176][177] Dai-Ichi arranged with Citigroup, its condominium partner, to jointly sell both condominium units.^[177] Richard and Eric D. Hadar, a father-and-son venture, bid $725 million for Dai-Ichi’s ownership stake in January 2001. For the purchase, Eric Hadar had arranged a $525 million first mortgage from Deutsche Bank and a $150 million mezzanine loan from the government of Singapore.^[176][178] The sale was delayed after Boston Properties offered to buy Dai-Ichi’s stake.^[179] Eric Hadar’s company, Allied Partners, along with Boston Properties, ultimately finalized their purchase of both condominium units that April.^[180][181] The building cost $755 million, including closing costs and taxes, and Citigroup relocated to 399 Park Avenue.^[117][182] One of the stilts was structurally reinforced following the September 11 attacks,^[103][104] and protective bollards were installed on the sidewalk.^[183]

Boston Properties bought Allied Partners’ stake in the Citigroup Center in 2006 for $100 million.^[184][185] The same year, Boston Properties began rebranding the building as «601 Lexington Avenue».^[186] A new Lexington Avenue lobby was constructed and the tower stories’ entrance was relocated from 53rd Street to Lexington Avenue.^[111][187] In addition, a ramp was installed on 53rd Street and a reception area was added to the northern entrance of St. Peter’s Church.^[117] The name change became effective in 2010.^{[117][188][189]} Boston Properties was also considering selling naming rights to the building.^[190] By 2013, Citigroup only occupied three stories at 601 Lexington Avenue.^[191] The next year, Boston Properties sold a 45 percent ownership stake in 601 Lexington Avenue, along with a proportional stake at the Atlantic Wharf Office Building and 100 Federal Street in Boston, to Norges Bank Investment Management for a combined $1.5 billion.^[192][193]

In mid-2016, the New York City Landmarks Preservation Commission (LPC) proposed protecting twelve buildings in East Midtown, including 601 Lexington Avenue, in advance of proposed changes to the area’s zoning.^[194] At the time, Boston Properties was contemplating renovations to the building; the company filed alteration plans for the plaza that July,^[59] and it was vacating the space in the office annex.^[195] On December 6, 2016, the LPC designated 601 Lexington Avenue as a city landmark.^{[3][196][197]} The designation made 601 Lexington Avenue the city’s youngest landmark at that time.^[196] The same month, Boston Properties announced plans to renovate the office annex, which would be rebranded 159 East 53rd Street.^[198][199] Shortly afterward, in March 2017, Gensler revealed its design for a refurbished entry plaza and a new atrium space.^[200][201] That June, work on the plaza commenced and the original fountain was demolished, despite being part of the landmark designation.^[64] All of the space at the 159 East 53rd Street annex was leased to NYU Langone Health in 2018.^[202][203] Following the completion of the renovation, in late 2019, Anna Castellani signed a lease to operate a 10,000 sq ft (930 m²) food hall at the base of 601 Lexington Avenue.^[204][205] In October 2019, London-based company etc.venues signed a lease to operate a 30,000 sq ft (2,800 m²) conference center on the 14th floor.^[206]

In December 2021, Boston Properties and Norges Bank Investment Management refinanced 601 Lexington Avenue with a $1 billion, 10-year fixed rate mortgage from a consortium of four banks.^[207][208] At the time, the building’s office space was 96.3 percent occupied, and the tenants largely included financial firms and law offices.^[209] With about 326,000 square feet (30,300 m²) of space, the Blackstone Group was one of the building’s largest tenants in 2022.^[210][211] Other large tenants included Citibank, Kirkland & Ellis, and Freshfields Bruckhaus Deringer.^[209]

Impact[edit]

Critical reception[edit]

During Citicorp Center’s construction, the building received large media attention, it had been one of three new office buildings in Manhattan whose plans were approved in 1974.^[85] After the design was announced, Ada Louise Huxtable criticized the design in The New York Times, saying the tower «has neither romanticism nor structural rationalism but, instead, appears to have been painstakingly invented with a tortured logic through a series of pragmatic and esthetic compromises».^[24][212] As the building was being completed, Huxtable took a less harsh tone to the building, saying that it contained a «clear desire for design quality» despite the drawbacks of the form and roof.^[85][213] A writer for the New York Daily News said: «Put this in Cleveland and it would be the eighth wonder of the world. In New York people hardly look up.»^[214] Suzanne Stephens wrote for New York magazine that the building was «little more than a modern Fifties high rise in drag»,^[24][97] considering the rooftop and base to be wasteful with space.^[97]

After the building’s completion, it received mixed reception. Paul Goldberger wrote for The New York Times that the roof «is a lot more fun to look at than almost any building top in years», with a reflective facade and a varied form, but the overall design «stops short of doing anything really radical».^[100] Jack Egan wrote similarly for The Washington Post, saying that the building had distinctive design features but did not appeal to either nostalgia or novel innovation.^[40] Huxtable regarded the plaza as an architectural success but observed in January 1978 that very few people used it.^[162] The interior space was described by August Heckscher II, a former New York City parks commissioner, as «an amenity in which we can all rejoice».^{[76][117][215]} Nevertheless, Heckscher believed the atrium’s silver cladding and light fixtures to be «cold» and suggestive of the indoors,^[76][215] and Stephens found the space to be «claustrophobic» and a «stratified success» whose benefits did not transcend class boundaries.^[76][216]

Other critics described Citicorp Center in a largely positive light. John Tauranac described the tower as the «most dramatic new skyscraper» in New York City since the completion of 30 Rockefeller Plaza several decades prior.^[85][217] Architectural writer Robert A. M. Stern wrote that Citicorp Center was the summation of a «unique architectural and urbanistic character that made Fifty-third Street at once an enclave within midtown and a microcosm of midtown itself».^[13] William H. Whyte particularly praised the structure as juxtaposing «a lot of elements at the right moment», particularly the exterior plaza and sidewalk.^[7] The building was also praised by publications outside the New York City area.^[85] The Baltimore Sun described the building as containing «simplicity […] that goes beyond sophistication»,^[26] while The Observer of London called it «a unique contribution to the East Side skyline».^[85]

Awards and use as icon[edit]

Upon Citicorp Center’s completion, it received several architectural awards. In 1978, the City Club of New York gave the building a Bard Award, which recognized «excellence in architecture and urban design».^[218] The same year, it received the American Institute of Steel Construction’s Architectural Award of Excellence.^[20][85] The American Institute of Architects gave the building an Honor Award in 1979.^{[2][219][220]} Furthermore, Hugh Stubbins and Associates received the AIA’s R.S. Reynolds Memorial Award in 1981 for its use of aluminum in the design of Citicorp Center.^{[220][221][222]}

The sloped roof of the building has been used for branding; for instance, it is included on the label of Chock full o’Nuts coffee.^[223] The roof was also depicted in the Manhattan Mini Storage logo, where the top left corner of the first letter «M» was sloped like the Citigroup Center.^[224] Additionally, since 2014, the New York Mets have sometimes used a logo that has included the Citigroup Center, as the bank also sponsors the Mets’ home stadium, Citi Field.^[225]

See also[edit]

• List of New York City Designated Landmarks in Manhattan from 14th to 59th Streets
• List of tallest buildings in New York City
• List of tallest buildings in the United States
• List of tallest freestanding steel structures

References[edit]

Notes[edit]

Citations[edit]

Sources[edit]

• «At the core of the Apple» (PDF). Progressive Architecture. Vol. 59, no. 12. December 1978.
• «At New York’s Citicorp Center, a structure of masterly invention underlies the urbane face of a skyscraper in the grand manner» (PDF). Architectural Record. Vol. 159, no. E3. August 1978. pp. 66–71.
• Hellman, Peter (February 24, 1974). «How They Assembled the Most Expensive Block in New York’s History». New York. Vol. 31. pp. 31–37.
• «Legs centered under each face carry diagonally braced tower» (PDF). Engineering News-Record. June 24, 1976. pp. 68–70.
• Morgenstern, Joseph (May 25, 1995). «The Fifty-Nine-Story Crisis». The New Yorker. pp. 45–53.
• Postal, Matthew A. (December 6, 2016). «Citicorp Center» (PDF). New York City Landmarks Preservation Commission.
• Schmertz, Mildred F. (June 1978). «Citicorp Center: If You Don’t Like the Crown Look At Its Base» (PDF). Architectural Record. Vol. 163, no. 7.
• Stern, Robert A. M.; Mellins, Thomas; Fishman, David (1995). New York 1960: Architecture and Urbanism Between the Second World War and the Bicentennial. New York: Monacelli Press. pp. 490–496. ISBN 1-885254-02-4. OCLC 32159240.

External links[edit]

• Official website

From Wikipedia, the free encyclopedia

The Citicorp Center engineering crisis was the discovery, in 1978, of a significant structural flaw in Citicorp Center, then a recently completed skyscraper in New York City, and the subsequent effort to quietly make repairs over the next few months. The building, now known as Citigroup Center, occupied an entire block and was to be the headquarters of Citibank. Its structure, designed by William LeMessurier, had several unusual design features, including a raised base supported by four offset stilts, and diagonal bracing which absorbed wind loads from upper stories.

In the original design, potential wind loads for the building were calculated incorrectly. The flaw was discovered by Diane Hartley, an undergraduate student at Princeton University who was writing a thesis on the building which was communicated to the firm responsible for the structural design. However, LeMessurier asserted that he spoke with a young male student of architecture whose questioning prompted him to recalculate the wind loads^[1] — now identified as Lee DeCarolis.^[2] Concerned about the quartering wind loads should the power to the mass dampers be lost, he investigated the structural integrity of the building. Worried that a high wind could cause the building collapse, reinforcements were made stealthily at night while the offices were open for regular operation during the day. Estimates at the time suggested that the building could be toppled by a 70-mile-per-hour (110 km/h) wind, with possibly many people killed as a result. The crisis was kept secret until 1995 and Hartley had no knowledge of the significance of her work until after that time.

The triggering event (according to LeMessurier and Hartley) was known to be high winds and NYC had plans to evacuate Citicorp and the surrounding buildings if high winds did occur.^[3] A hurricane did threaten NYC during the retrofitting, but it diverted before arriving.

A NIST re-assessment using modern technology has determined that the quartering wind loads were not the threat that LeMessurier and Hartley had thought. They recommend a reevaluation of the original building design to determine if the retrofitting was warranted.^[4]

Background[edit]

The Citigroup Center, originally known as Citicorp Center, is a 59-story skyscraper at 601 Lexington Avenue in the Midtown Manhattan neighborhood of New York City.^[6][7] It was designed by architect Hugh Stubbins as the headquarters for First National City Bank (later Citibank), along with associate architect Emery Roth & Sons.^[8][9][10] LeMessurier Associates and James Ruderman were the structural engineers, and Bethlehem Steel was the steel contractor.^[9][11] The building was dedicated on October 12, 1977.^[12][13]

As part of Citicorp Center’s construction, a new building for St. Peter’s Lutheran Church was erected at the northwest corner of the site; by agreement, it was supposed to be separate from the main tower.^[14][15] To avoid the church, the tower is supported by four stilts^[9][16] positioned underneath the centers of each of the tower’s edges.^[17] (Early plans called for the supports to be placed under the tower’s corners, but the agreement with the church prevented that.^[18]) To allow this design to work, Bill LeMessurier specified that load-bearing braces in the form of inverted chevrons be stacked above the stilts inside each face of the building. These braces are designed to distribute tension loads that are created by wind from the upper stories down to the stilts.^[19][20]

The long, multi-story diagonal braces had to be fabricated in sections and assembled on site, requiring five joints in each brace. LeMessurier’s original design for the chevron load braces used welded joints. To save money, Bethlehem Steel proposed changing the construction plans to use bolted joints, a design modification that was accepted by LeMessurier’s office but not known to the engineer himself until later.^[17]

For his original design, LeMessurier calculated wind load on the building when wind blew perpendicularly against the side of the building, as these were the only calculations required by New York City building code. Such winds are normally the worst case, and a structural system capable of handling them can easily cope with wind from any other angle. Thus, the engineer did not specifically calculate the effects of diagonally-oriented «quartering winds».^[17][21]

Discovery[edit]

In June 1978, Princeton University engineering student Diane Hartley was writing her senior thesis about Citicorp Center’s design at the suggestion of her professor, David Billington.^[22][23] As part of that work she analyzed the structural design and calculated stresses from quartering winds, finding them higher than the maximum expected stress values provided to her by LeMessurier’s firm. Billington, in his feedback on Hartley’s thesis, also questioned the figures provided by the firm. Hartley asked her contact there about the discrepancy and was assured the building could handle the forces, so she dropped the issue. Hartley’s concerns and the response she received are documented in her thesis.^[22] LeMessurier was separately designing a similar building with wind braces in Pittsburgh, and a potential contractor questioned the expense of using welded rather than bolted joints. LeMessurier asked his office how the welds went at the Citicorp construction and was then told bolts had been substituted.^[22]

In June 1978, LeMessurier was answering questions via phone with a young architectural student^[24] now identified as Lee DeCarolis.^[2] That phone call convinced him to recalculate the wind loads, including the diagonal wind loads.

On July 24, 1978, LeMessurier went to his office and conducted calculations on Citicorp Center’s design.^[22][21] He found that, for four of the eight tiers of chevrons, such winds would create a 40 percent increase in wind loads and a 160 percent increase in load at the bolted joints.^[17] Citicorp Center’s use of bolted joints and the increased loads from quartering winds would not have caused concern if these issues had been isolated from each other. However, the combination of the two findings prompted LeMessurier to run tests on the structural safety.^[25] The original welded-joint design could withstand the load from straight-on and quartering winds, but a 70-mile-per-hour (110 km/h) near-hurricane force quartering wind would exceed the strength of the bolted-joint chevrons.^[20][22] LeMessurier also discovered that his firm had used New York City’s truss safety factor of 1:1 instead of the column safety factor of 1:2.^[20]

On July 26, LeMessurier visited wind-tunnel expert Alan Garnett Davenport at the University of Western Ontario. Davenport’s team conducted calculations on the building and found not only that LeMessurier’s modeling was correct, but also that, in a real-world situation, member stresses could increase by more than the 40 percent LeMessurier had calculated.^[22][26] LeMessurier then went to his Maine summer home on July 28 to analyze the issue.^[22][26] With the tuned mass damper active, LeMessurier estimated that a wind capable of toppling the building would occur on average once every 55 years.^[27][22] If the tuned mass damper could not function due to a power outage, a wind strong enough to cause the building’s collapse would occur once every 16 years on average.^[27]

Repairs[edit]

LeMessurier agonized over how to deal with the problem. If the issues were made known to the public, he risked ruining his professional reputation as well as causing panic in the immediate area surrounding the building, as well as to occupants.^[28] LeMessurier considered never bringing the issue up, and he also briefly contemplated killing himself before anyone else found out about the defect.^[29][30] LeMessurier ultimately contacted Stubbins’s lawyer and his insurance carrier. LeMessurier then contacted Citicorp’s lawyers, the latter of which hired Leslie E. Robertson as an expert adviser.^[28] Citicorp accepted LeMessurier’s proposal to weld steel plates over the bolted joints, and Karl Koch Erecting was hired for the welding process.^[31] Very few people were made aware of the issue, besides Citicorp leadership, mayor Ed Koch, acting buildings commissioner Irving E. Minkin, and the head of the welder’s union.^[20][31]

Construction crews started installing the welded panels at night in August 1978. Officials made no public mention of any possible structural issues, and the city’s three major newspapers had gone on strike.^[32][31] Officials barely acknowledged the issue, instead describing the work as a routine procedure. Henry DeFord III of Citicorp claimed the Citicorp Center could already withstand a 100-year wind^[33] and that there were no «noticeable problems in the building at all».^[34] As precautions, emergency generators were installed for the mass damper, strain gauges were placed on critical beams and weather forecasters were engaged.^[22] Citicorp and local officials created emergency evacuation plans for the immediate neighborhood.^[20][35] However, these evacuation plans were not publicized at the time. This was in spite of the fact that thousands of people could have been killed in a potential collapse.^[29] Six weeks into the work, a major storm (Hurricane Ella) was off Cape Hatteras and heading for New York. With New York City hours away from emergency evacuation, the reinforcement was only half-finished. Ella eventually turned eastward and veered out to sea.^[20][35]

Repairs were completed in October 1978, before the media resumed publishing. LeMessurier claimed a wind strong enough to topple the repaired building would only occur once every 700 years.^[32][36] Stubbins and LeMessurier covered all of the repair costs, which were estimated to be several million dollars.^[36]

Publication[edit]

Since no structural failure occurred, the work was only publicized in a lengthy article in The New Yorker in 1995.^[32][37] The 1995 story in The New Yorker described the student as a «young man, whose name has been lost in the swirl of subsequent events» who called LeMessurier saying «that his professor had assigned him to write a paper on the Citicorp tower».^[37][21] However, the student apparently never contacted LeMessurier directly.^[21][24] According to the website Online Ethics, when one of LeMessurier’s colleagues asked whether the student was female, «LeMessurier responded that he didn’t know because he had not actually spoken with the student.»^[24] LeMessurier had died in 2007 without specifying how much of the exchange between the student and the engineer had been brought to his attention.^[22]

Hartley identified herself as the engineering student in 2011, years after the New Yorker article was published.^[21] Hartley said she had spoken with Joel S. Weinstein at LeMessurier’s office.^[21]

The student that LeMessurier spoke to by phone who prompted his recalculation of the wind loads^[1] has identified himself in an article posted to OnLineEthics.com.^[2] His name is Lee DeCarolis. He learned in 2011 how he played a part in the Citicorp Building history from Einstein’s Refrigerator by Steve Silverman. By that time, LeMessurier had died. While he mentioned his part to acquaintances, and even wrote a play about it, he revealed himself to the public at large only after a NIST reassessment had determined that the wind loads weren’t the threat that Hartley and LeMessurier had determined,^[4] stating that he could therefore not be accused of seeking or stealing glory.

Ethical questions[edit]

According to the American Institute of Architecture Trust case study,^[22] «many have viewed the actions of LeMessurier as nearly heroic, and many engineering schools and ethics educators now use LeMessurier’s story as an example of how to act ethically.» However, others have criticized LeMessurier for his lack of oversight that led to the issues, as well as his lack of honesty toward neighborhood residents, architects, engineers, and other members of the public when the issues were discovered. Architect Eugene Kremer discussed the ethical questions raised in this case.^[29] Kremer mentioned six key points:^[38]

1. Analysis of wind loads. In his initial plans, LeMessurier relied only on calculations required by building codes, rather than checking all calculations.^[17][29]
2. Design changes. The builders had made a quick decision to use bolted joints without consulting LeMessurier.^[17][29]
3. Professional responsibility. Before LeMessurier decided to make Citicorp aware of the design defects, he briefly considered concealing the issues instead.^[29][30]
4. Public statements. In press interviews and releases at the time, officials either omitted or lied about details of the defects.^[29][39]
5. Public safety. When Hurricane Ella threatened the city in August and September 1978, evacuation plans for the surrounding area were made in secret.^[35]
6. Advancement of professional knowledge. Concealing this problem for almost 20 years prevented ethical and engineering learning that could have taken place.^[29]

References[edit]

Sources[edit]

• Morgenstern, Joseph (May 25, 1995). «The Fifty-Nine-Story Crisis». The New Yorker: 45–53.
• Postal, Matthew A. (December 6, 2016). «Citicorp Center» (PDF). New York City Landmarks Preservation Commission.
• Stern, Robert A. M.; Mellins, Thomas; Fishman, David (1995). New York 1960: Architecture and Urbanism Between the Second World War and the Bicentennial. New York: Monacelli Press. ISBN 1-885254-02-4. OCLC 32159240.