New Comcast Tower will be Philadelphia’s Tallest Building
Comcast is adding to its footprint in downtown Philadelphia as B. Pietrini and Sons, King of Prussia, PA is the concrete contractor who is pumping and placing the concrete for the new Comcast Technology Center next to the existing Comcast Center that was topped out in 2007. The new tower, scheduled to be topped out in early 2017, will be the tallest in the United States outside of New York and Chicago. It will eclipse the height of the neighboring Comcast structure by more than 200-feet. The new structure will be the highest that B. Pietrini’s crew have ever worked on in the company’s nearly 70 year history.
Pumping began in November of 2014 with a 3,800-yard foundation pour that measured 102 by 96-feet. Concrete was pumped by four of Pietrini’s 14 Schwing boom pumps to a thickness of 10-feet. The monolithic slab consumed more than 400-tons of reinforcing steel. The night pour began at 1:45 a.m. on a weekend to avoid traffic in the downtown location. The company’s Schwing S47 SX and S39 SX truck mounted pumps with placing booms were teamed with a pair of Schwing S34 X boom pumps to provide a continuous flow of concrete from more than 375 truck loads dispatched from two suppliers – SJA Concrete of Philadelphia, and Action Concrete Supply of Sharon Hill. The B. Pietrini crew of 45 workers took 12 hours to complete the pour.
The building site leaves little room for a concrete pump and access for truck mixers. The Schwing SP8800 concrete pump purchased for the project is straddling the sheeting and angled into the site to keep truck mixers off the street. The powerful 2020-7 150/90 pump kit can place up to 152 cubic yards per hour when configured in the high volume mode and apply up to 2364 psi on the concrete in the high pressure mode. A 500-horsepower diesel engine powers the unit that includes twin 190 hydraulic pumps, eight inch material cylinders, and the HP Rock Valve with dual shifting cylinders, ideal for high pressure applications and capable of handling the harshest mixes with up to 2.5” aggregates.
The concrete core precedes steel erection on the project. At ground level the core accommodates eight elevator banks. The core walls are four-feet thick at ground level and taper to two-feet thick at the top. The placing crew was utilizing a Schwing SPB 28 separate placing boom for core pours. The boom’s 93-feet of horizontal reach covers the entire core and is mounted on an X-frame attached to the climbing form system. A hydraulic power pack powers the boom and two-way radios connect the pump operator with the boom operator.
In a first for high-rise construction in the U.S., the crane used for constructing the core wall and slabs was attached directly to the concrete core walls. As the crane moves up, a support structure is tied to the outside of the core. The major benefit is that without a “tower” no knockouts are needed in the lower decks allowing earlier build-out and occupancy. “They have been building out the lower floors for eight months and will have tenants moving in this Fall,” according to Francis Pietrini, CEO of the company, “While the Four Seasons Hotel on the upper floors won’t be open until Spring of 2018.”
The buildings bottom floors cover 40,000 square feet up to the sixth level, then taper down to 28,000 square feet up to the hotel level on the 48th floor. The very top floors from 48 to 60 will be 14,000 square feet each. The building’s spire will reach to 1,176-feet. The self-consolidating concrete strength varies from 10,000 psi in the core walls at the base to 6,000 psi at the top. “The 4000 psi lightweight concrete has been pumping well, “according to Marc Pietrini, President of the company, “Our ready-mix supplier, SJA, has been keeping the mix very consistent.” More than 65,000 cubic yards will be pumped on the project.
More than 1,300-feet of pipeline connects the pump to the placing crew. Deck pours vary from 400 yards on lower floors to 235 yards for the hotel floors at the top. The placing crew is pouring the deck by breaking back pipe and dragging the end hose. “We are getting all we need out of the pump and we don’t even have it on the high pressure side,” according to Pietrini Project Manager Mike Ricchezza. Four cantilevered wings that jut from each corner of the core from the 42nd floor to the 50th floor, were a challenge for the crew to form and pour. “There was very little to build off of,” Fran Pietrini states, “But that is the advantage of our company performing the forming, pouring and finishing. We have the resources to manage these challenges.”
Designed by world-renowned architect Lord Norman Foster of Foster + Partners, with the Liberty Property Trust Part Owner & Developer with Thornton-Tomesetti, Inc. Structural Engineer, and L.F. Driscoll, LLC as Construction Manager, the glass and stainless steel tower will complement Comcast Center as a new energetic dimension to Center City. The 1.5 million rentable square foot project will include a block-long lobby with a glass-enclosed indoor plaza. The lobby will feature a restaurant and a new concourse will provide direct connections with SEPTA’s Suburban Station, enhancing accessibility and providing new options for commuters. The Four Seasons Philadelphia has held court on Logan Square for more than 30 years, but with the construction of the new tower, the hotel will transition to new sky-high digs with 225 luxury rooms and a roof-top restaurant.
The Comcast Technology Center has generated a substantial amount of upfront economic activity during the project’s construction period, including $2.75 billion in economic activity within the commonwealth and the creation of more than 20,000 temporary jobs. The estimated direct and indirect ongoing impact of the Comcast Technology Center is also remarkable, creating almost 4,000 new permanent jobs with the Commonwealth and 2,800 new permanent jobs with the City. The project will also produce $30.7 million in annual Commonwealth tax revenues and $21.5 million in annual City tax revenues.