Famous NYC skyscraper was almost toppled by winds

The Citicorp Tower has been a Manhattan skyline icon for nearly a half-century with a glimmering silhouette and unique, prism-topped roof. 

The 54-story skyscraper was dedicated on Oct 12, 1977, by Gov. Hugh Carey and Mayor Abe Beame. Less than a year later, chief engineer William LeMessurier found it had a 1 in 16 chance of toppling over in hurricane winds.

The Citicorp Tower has been a beacon of the Manhattan skyline for nearly five decades. Bloomberg via Getty Images

The discovery set off a frantic effort to save it without letting the public know — with the summer hurricane season fast approaching.

It was “one of the greatest engineering crises in history,” Michael M. Greenburg, the author of “The Great Miscalculation: The Race to Save New York City’s Citicorp Tower” (NYU Press/Washington Mews; out Tuesday), told The Post.

“I was immediately drawn to LeMessurier’s story — the moral aspect of it, the dichotomy between heroism and cover-up.”

LeMessurier, who was busy on many other projects, knew he hadn’t paid enough attention to Citicorp after he turned it over to a team of engineers. He had to decide between alerting Stubbins and Citibank chairman Walter Wriston to his mistakes — thus jeopardizing his reputation and career — or remaining silent and praying the worst wouldn’t happen.

 Although LeMessurier ultimately came to the rescue in time, his legacy is tainted, Greenburg writes, by his “failure to provide adequate direction and oversight …  in the development of the Citicorp Center engineering drawings, calculations and revisions.”

Greenburg weaves a compelling, thriller-like narrative. The 1977 blackout plunged the metropolis into darkness and rioting. The city had barely averted bankruptcy and corporations were fleeing for the suburbs.

The exception was Citibank. Wriston wanted to create a signature skyscraper on Manhattan’s East Side. He secretly assembled a large site between Lexington and Third Avenue, between East 53rd and 54th.

One challenge remained: St. Peter’s Lutheran Church, at the corner of Lexington Avenue and East 54th Street, which was also a cultural center and jazz mecca.

A new book delves into a little known chapter in the tower’s history.

The church agreed to sell its land to Citibank for $9 million under strict conditions: The bank would build a new church structure “physically separate” from the office tower. Moreover, the “air space above approximately two-thirds of the footprint of the new church would remain open” and “no element of the tower would encroach on or interfere with the church building below.”

To design the tower around the church, Stubbins and LeMessurier envisioned a “skyscraper on stilts.” Rather than position support columns at its four corners, they would stand under each of the building’s middle faces with the tower cantilevered above a public plaza.

That posed an engineering challenge. To stabilize the structure, LeMessurier devised a network of triangular, V-shaped internal braces that were to be welded together to stabilize the building.

 But soon after the tower opened in October 1977, the engineer realized he had inadequately accounted for the potential effect of strong winds. Although the tower would withstand 100-mph blasts on any of its faces, a “quartering wind” — one that struck at an angle, thus impacting two faces at the same time — was much more dangerous.

Chief engineer William LeMessurier discovered a major flaw in the building’s design less than a year after it was completed. Courtesy of William Thoen

When LeMessurier reviewed the stabilizing techniques his team had used, he learned — much to his dismay — that the braces had been cheaply bolted together, not welded as called for in the original plan.

He shared the grim news with Stubbins, bankers and city officials. The Red Cross was tapped to secretly prepare an evacuation plan in the event the tower was close to toppling.

As one tropical storm after another seemed set to bear down on New York, all hands agreed that only a crash project to weld the braces on all 54 floors could save the tower — filled with thousands of employees unaware of the peril — from possible catastrophe.

The tower’s unique design made it vulnerable to high winds. Tdorante10/ Wikipedia/ CC

The night manager of the nearby Waldorf-Astoria Hotel, a cousin of one of LeMessurier’s employees, set up a “war room” for LeMessurier’s team in Frank Sinatra’s private suite where they devised a total retrofitting of Citicorp’s structural bracing.

Greenburg writes that, every night for two months, “a slew of over twenty face-armored union welders” loaded equipment through loading docks and “ascended service elevators sans the probing gaze of New York’s major newspapers,” which were conveniently on strike.

The work was finished by the end of October. At last, LeMessurier “could breathe again,” the author notes.

The tower was ultimately saved, but LeMessurier’s reputation was tarnished. Getty Images

Still, Greenburg, who never met the engineer, notes that he remained haunted until his death in 2007.

The Citicorp Tower, he writes, “born of courage and design brilliance, forever bears the mark of an audacious  and all-too-human engineer and his willingness to risk all.”