Cira Takes Centre Stage

Cira Centre adds a new look to Philadelphia's skyline

By Harris M. Steinberg, AIA

Philadelphia is witnessing the addition of the first new skyscraper to its skyline in more than a decade with the development of the 28-story Cira Centre. The design and construction teams are addressing significant challenges to make the 727,000-sq.-ft. office tower above neighboring 30th Street Station a reality.

Cira Centre required 7,200 tons of project steel, including a 36-ton column designed to accommodate 1,600 lbs. per ft.

A new icon is emerging above the western bank of the Schuylkill River in Philadelphia.

The 28-story Cira Centre office tower, designed by internationally renowned Cesar Pelli & Associates Architects of New Haven, Conn., is the first new skyscraper to rise above the city in more than a decade, adding a dramatic element to the Philadelphia skyline and drawing attention to the neighboring University City area.

Brandywine Realty Trust is developing the 727,000-sq.-ft. tower alongside 30th Street Station, Amtrak's second-busiest station in the United States with 2.5 million rail commuters passing through it each year. Cira Centre will also tower above the nearby campuses of the University of Pennsylvania and Drexel University.

With little obstruction from surrounding structures, Cira Centre will have a commanding presence in the neighborhood. Contrasting with the Beaux-Arts limestone solemnity of 30th Street Station, the new tower, sheathed in a structurally glazed customized curtain wall system, will be visible from 360 degrees.

"[The multifaceted structure] is interesting on all sides - its crystalline form allowing the different facades to be transformed [visually] by the taut glass skin throughout the day and year," said Mark Shoemaker, AIA, associate principal of Cesar Pelli & Associates and the design team leader.

Brandywine sought to create a building that was "practical and workable" on a difficult site, said Jeffrey R. Weinstein, the firm's vice president for construction. The company selected the one portion of the site without any active rail lines or other physical impediments, but it still presented obstacles to the design and construction team.

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"The biggest challenge that the team faced was building a multistory high-rise on a postage stamp site bounded on three sides," said Richard Treglown, project manager for Turner Construction of Philadelphia. Treglown is a veteran of four Philadelphia office towers and the recently completed Lincoln Financial Field for the Philadelphia Eagles.

A tight site

The Cesar Pelli design, pictured in this rendering, is a multifaceted structure with a crystalline form.

Access to the tight site is limited to Arch Street on the southern side. An existing parking deck, which couldn't take additional structural loads, borders to the east. A parking garage was recently completed to the north, and the freight lines of Penn Coach Yards on the west side couldn't have service interruptions.

To further complicate matters, Arch Street, built on a deck above the floodplain, is a Pennsylvania state highway that handles significant volume of traffic exiting and entering Interstate 76 at 30th Street Station.

Site constrictions forced demolition to occur within 15 ft. of a highly sensitive 25,000-volt electrical line - the catenary for the freight line electrical power. On the east, adjacent to Amtrak's Northeast Corridor high-speed rail line, tying in a storm drainage line required coordination with Amtrak to ensure that service was not disrupted on the busy rail corridor.

Weinstein said his development team meets with Amtrak representatives weekly and there is good cooperation and coordination with the rail service provider. Deliveries to the basement-level loading dock have to be scheduled with an Amtrak flagman so that the delivery trucks can cross the freight lines without interrupting service.

Without layout or storage space onsite, all deliveries are staged on Arch Street between 9:30 a.m. and 4:30 p.m. so as not to disrupt rush-hour traffic. Everything is lifted off trucks in front of the building and hoisted up and installed. No materials will be stored on site until the building is closed in and sealed.

The building sits on a deck located 20 ft. above track level, which meant tying into utility mains beneath Market Street one block to the south. Luckily, the architects of 30th Street Station included room-sized subterranean tunnels stretching along all sides of the block-long building.

Used originally for mail transfer from railcars to the main post office building at 30th and Market streets, these now-abandoned tunnels proved the prefect conduit for water, gas, sanitary, electrical and telephone lines.

Massive steel

Construction required significant coordination with Amtrak and the site's other neighbors.

The need to create clear-span floor plates for office tenants required a structural steel frame with massive transfer girders - some between 32 and 42 ft. long. The frame rests on 34, 50-ft.-deep caissons that Treglown said average between 6 and 8 ft. in diameter.

The 7,200 tons of project steel includes what Treglown said is the biggest steel he has ever seen. For example, he highlighted a 36-ton column designed to accommodate 1,600 lbs. per ft.

Timing is everything on a fast-track construction project such as this, and steel was purchased just as the U.S. Army was requiring 1- and 2-in.-thick steel plate to reinforce Humvees in Iraq. That impacted the supply of steel for the perimeter columns and initially set the project back seven weeks.

The Cira Centre was topped out in November and is on track for completion in the fall.

But Treglown said Canam, a Canadian steel supplier, worked with the building's structural engineers, Ingenium of Houston, Texas, to overcome initial delays and lost time was made up in 2.5 months.

All involved with the project credit the excellent working relationships between the team members as a key component of the project's success to date.

"There are no rigid and formalized relationships between the players," said Malcolm Quinion, RIBA, project manager for Bower Lewis Thrower Architects of Philadelphia, the project's executive architect. "Rather, everyone gets down to issues and works together and contributes to solutions."

The Cira Centre project is on track to be completed in the fall.

Harris M. Steinberg, AIA, is the executive director of Penn Praxis of the School of Design of the University of Pennsylvania.

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