270 Park Avenue
JPMorgan Chase’s new headquarters rises 1,388 feet from one of the hardest sites in Manhattan: a full block with Grand Central’s train tracks under three quarters of it. Foster + Partners designed the tower, and Severud Associates engineered it to stand where ordinary foundations couldn’t go.
A headquarters over the tracks
The building that stood here
For six decades the block belonged to the Union Carbide Building, a 52-story glass tower completed in 1960 and designed at SOM by Gordon Bunshaft and Natalie de Blois, who is often credited as its principal designer. It was built for about 3,500 people. When JPMorgan announced it would come down, preservationists pressed for landmark status, but the Landmarks Preservation Commission declined.
Room to grow
What made a far larger tower possible was the city’s rezoning of East Midtown, and this was its first major project. The rules let a new building grow by buying the unused development rights, often called air rights, of nearby landmarks. JPMorgan bought about 680,000 square feet of them from Grand Central Terminal and 50,000 from St. Bartholomew’s Church. The building cost some $3 billion.
Inside
The result holds about 2.5 million square feet: eight trading floors, a triple-height dining and meeting hall called the Exchange, a wellness center and a client floor at the top. The art program includes works by Maya Lin, Gerhard Richter and Refik Anadol. JPMorgan expects 10,000 employees by the end of 2025; its engineers put the capacity at 14,000.
All-electric
It is also New York City’s largest all-electric skyscraper, running on renewable power from a New York State hydroelectric plant. Triple glazing and automatic shades admit about 30 percent more daylight, water reuse cuts consumption by more than 40 percent, and the ventilation brings in twice the usual fresh air.
The building at human scale
About 140 feet taller than the Empire State Building’s roof.
Wikipedia · Empire State BuildingAs heavy as about four fully loaded 747 jets, and 25 feet deep: taller than a two-story house.
STRUCTURE · 747-400Roughly half the weight of an aircraft carrier, resting on a patch about 8 feet square.
STRUCTURE · Nimitz classHow long one full sway takes, side to side and back. Big buildings move slowly.
Peer reviewHow far the top would move in a once-in-50-years storm. For a 1,388-foot tower, that’s tiny.
Peer reviewWeight and wind
Before following the build, it helps to know what a tower is up against. Gravity pulls it down; wind pushes it sideways. The diagram isolates the devices engineers use against each, including the one that defines 270 Park: the transfer structure, which carries columns around an obstacle.
A tower comes down, a tower goes up
Demolition and construction overlapped. From 2019 to 2021 the Union Carbide Building was taken apart from the top down inside a scaffold shroud, at the time the tallest building ever demolished on purpose. Beneath it, new foundations were already going in, and the first steel of the new tower rose in January 2021, before the old one was gone.
A braced core and five sets of outriggers
Out of the ground, the tower is a steel frame organized around a braced core. Outrigger trusses at levels 11, 18, 29, 38 and 53 lock the core to the perimeter columns, diamond braces stiffen the east and west faces, and a 280-ton pendulum damper near the top tempers the sway. All of it comes down onto a single structure at the base.
The Tabletop
That structure exists because there was no room for ordinary foundations: train tracks run under most of the block. The engineers’ answer is a two-story steel transfer structure they call the Tabletop. Concrete walls are threaded between the tracks, with forged steel nodes on top. Above them, sloping columns and two 25-foot-deep girders gather the whole tower onto a handful of points.
One node
Each of those points is a forged steel block set on a concrete wall up to four feet thick, with tracks on either side. Post-tensioned tendons run down through the wall to caissons in the rock, so the column cannot lift when wind loads the far side of the tower. The concrete, steel and tendon details come from the 2020 peer review.
A small glossary
- Load path
- The route a building's weight (and the wind's push) takes from where it starts, down through floors, beams and columns, into the ground.
- Column
- A vertical member that carries weight down. The lowest columns carry every floor above them.
- Beam, girder
- A horizontal member that carries weight sideways to columns. A girder is a big beam that other beams rest on.
- Plate girder
- A girder built up from steel plates welded together: two flanges (top and bottom) and a tall web between them. 270 Park's are 25 ft deep.
- Truss
- A frame of straight members in triangles. Triangles can't change shape, so a truss is stiff and light.
- Brace
- A diagonal member that stops a frame from leaning, like the diagonals in a bookshelf back.
- Core
- The stiff tube in the middle of a tower, around the lifts and stairs. At 270 Park it's a steel frame full of braces.
- Outrigger
- A very stiff arm, often a story-deep truss, that ties the core to the outer columns so the whole width of the building resists bending.
- Transfer structure
- A structure that catches columns that can't continue straight down and carries their load sideways to supports that can. 270 Park's Tabletop is one.
- Node
- A joint where several members meet. A forged node is shaped from a solid block of hot steel, not welded together from plates.
- Shear wall
- A concrete wall that resists sideways forces along its length; here the walls between the tracks also carry the tower's weight.
- Caisson, mini-caisson
- A foundation shaft drilled down to rock and filled with concrete or grout, usually with a steel casing. Mini-caissons are thin ones, useful where there's little room.
- Caisson cap
- A concrete block that joins the tops of several caissons so they work together.
- Post-tensioning
- Steel tendons threaded through ducts, pulled very tight with jacks and locked off. They squeeze concrete together or tie a structure down.
- Coupler
- A steel sleeve that joins two reinforcing bars end to end, used where there's no room to overlap them.
- Curtain wall
- The glass-and-metal skin hung on the outside of the frame. It keeps the weather out but carries no building load.
- Setback
- A step in where the upper part of a building is narrower than the part below.
- Tuned mass damper
- A heavy weight near the top, tuned to the building's own sway, that moves against the motion to reduce what people feel.
- psi
- Pounds per square inch: how much pressure concrete can take before crushing. Ordinary concrete is a few thousand psi; 270 Park's walls are 16,000.
- kip
- A thousand pounds. 100,000 kips is 100 million pounds, about 50,000 tons.
- Topping out
- The ceremony when the highest structural piece is set in place.