PROJECT OVERVIEW

Google’s new headquarters for thousands of employees in New York, N.Y., at St. John’s Terminal was constructed with innovation as a key component of the building’s interior and exterior design. The massive St. John’s Terminal, which spans two city blocks in lower Manhattan, consists of the building’s original three stories topped with nine new levels. This expansion to 12 stories, along with the need for two high-rise elevator cores, necessitated a unique design that would ensure that the existing structure could support the added load of steel framework and cast-in-place concrete floors.

BRIDGE BUILDING TECHNIQUES SAVE TIME AND MONEY

Working alongside Rizzani de Eccher (RDE), Jersey Precast developed a precast concrete building core with Lego-style connections. Collectively, the companies decided on match-casting for the core, an approach commonly used in bridge construction where each precast concrete element is cast against the previous one. By using this technology, extremely tight tolerances could be achieved while also mitigating error. The precast concrete core was built just like a bridge span but oriented vertically instead of horizontally.

George Hand II, Jersey Precast CEO, says that 298 segmental precast concrete units were manufactured to create the core. The units had a maximum weight of 84 tons (76 tonnes) and were about 29 ft 8 in. (9 m) long by 13 ft 6¾ in. (4 m) wide by 10 ft 4 in. (3 m) tall. In addition to the elements needed to build the core, Jersey Precast also provided 114 precast concrete stairs, 153 stair landing slabs, and 55 elevator landing slabs.

Using one trade “to furnish, install and erect a precast system with a steel system, the initial savings was in cranage. We only had two cranes on this entire structure. For a building of this size, it could easily handle four to five cranes if there was a subcontractor doing the core. That alone delivered several million dollars worth of savings for the project,” says Dave Pisacrita, Metropolitan Walters principal, the steel and core erector on the project.

Owner

Google

PCI-Certified Precast Concrete Producer

Jersey Precast

Architect

COOKFOX Architects

Structural Engineer

Entuitive

General Contractor

Turner Construction

Core Contractor

 Rizzani de Eccher (RDE)

Key Project Attributes

• The structural engineer, erector, and precast manufacturer collaborated on a novel solution—a building core of precast concrete panels with matching Lego-style connections instead of a costlier, more time-consuming cast-in-place option.
• Jersey Precast was able to enact safe workplace protocols to keep panel fabrication on track erect the precast panels with an onsite crew that was only one-quarter of the size of a cast-in-place team, making it easier to create safe worker distances.
• Precast for stairs, elevator lobbies and infill slabs was used, which saved time and boosted safety, allowing crews on steelwork and decks to avoid temporary ladders; as the core system rose, it made ongoing selective demolition safer by stabilizing the structure.
• The team used a polyurethane-poured form liner to give the panels a wood planking architectural finish, allowing the panels to serve as finished walls on the interior, avoiding the addition of drywall.

Project/Precast Scope

• 1.3 million square-foot structure; original three stories and nine new levels for a total expansion to 12 stories including two high-rise elevator cores
• Components included 298 precast panel segments, 114 precast concrete stairs, 153 stair landing slabs, and 55 elevator landing slabs