Nerves of steel: 150 North Riverside

 

The Pencil Building. Introducing 150 North Riverside: Chicago's Newest Architectural Marvel

From the moment it graced the Chicago skyline, passersby couldn't help but nickname it: 150 North Riverside. This striking 54-story office building, nestled along the river in downtown Chicago, captivates with its unique silhouette—a towering stylus thrust into the heart of the urban landscape. What's more astonishing is its ability to maintain such soaring height and mass on a mere 39-foot-wide foundation.

The very existence of 150 North Riverside stands as a testament to the unwavering determination of Riverside Investment & Development, backed by an exceptional Building Team led by Clark Construction Group, visionary architects at Goettsch Partners, and accomplished structural engineers at Magnusson Klemencic Associates (MKA). Despite technical challenges that deterred many for nearly a century, this project not only came to fruition but has set a new standard of architectural prowess.

Such tenacity did not go unnoticed. The judges for the Building Team Awards were thoroughly impressed, unanimously bestowing upon 150 North Riverside the coveted Platinum Award for this year's outstanding achievement.

Now, let's delve into what sets this project apart, beginning with its remarkable site.

 The gigantic crane worked from a barge in the river. Photo: Andrew Bruah.

 

NOT MUCH ROOM TO WORK IN

Five and a half years ago, following his tenure as president of the John Buck Company, John O’Donnell, now CEO of the newly established Riverside Investment & Development, acquired a two-acre parcel. This coveted site, a longtime ambition of O’Donnell, bordered the Chicago River to the east and was flanked by seven active Amtrak rail tracks to the west, which claimed the lion's share of the acreage. This left a mere 85-foot-wide strip for potential construction. However, there was a twist. The city reserved a 30-foot portion to extend the continuously expanding Chicago Riverwalk, while O’Donnell set a 45-foot minimum lease span. This resulted in a remaining 40-foot-wide expanse, just enough to accommodate a 6,318-square-foot base.

'We had a convergence of technical expertise that made the going-in risk more palatable.'

— Tony Scacco, Riverside Investment & Development

In order to create additional workspace, the team proposed the construction of a 1½-acre "bridge" or deck over the active rail tracks. Typically, belled caissons would have sufficed for structural support in such a scenario. However, Clark Construction, the general contractor, recognized from a nearby project that excavating belled caissons generates substantial messy waste that needs to be cleared, and they also entail a sizable rig that requires time for demobilization. Since pile driving was restricted to the early morning hours, between 1:00 to 5:00 a.m., to avoid conflicting with Amtrak service, belled caissons were not a viable structural option.

MKA, in collaboration with geotechnical consultant GEI, reengineered the foundations to utilize a 9½-inch-diameter "micropile" system. This allowed Clark Construction to employ a smaller rig that generated no waste and could be swiftly maneuvered in and out of the rail yard. However, it was imperative to limit the overall number of piles, which necessitated maximizing their strength. "We initially started with 400-kip micropiles, but GEI advised that the fewer times we needed to excavate, the better. Hence, we continued to escalate in strength," noted MKA’s Robert Chmielowski, PE, SE.

Over the course of approximately four months, Clark Construction installed over a hundred 600-kip micropiles—setting a new record for Chicago's highest-capacity piles—between the tracks. "In terms of strength, 600-kip is beyond comparison," remarked Chmielowski. For the tower foundation, MKA devised 16 fully reinforced caissons, each with a diameter of 10 feet, drilled six feet into the bedrock. The team also pre-planned the foundation reinforcement design to accommodate the addition of a floor midway through construction at the developer’s request.

The street-level bridge provided Clark Construction with the means to introduce upgraded utility service and transport heavy equipment onto the site, expediting the progress. As for Amtrak service, "We experienced zero interruptions," affirmed Clark Construction’s Project Executive, Chris Phares, PE.

This addressed the Amtrak aspect of the project. Handling the riverside edge of the site presented an entirely new challenge in creative problem-solving.

 An elaborate micropile, caisson, and steel framework supports the tower. Magnusson Klemencic Associates.

 

BUILDING ON EARNED KNOWLEDGE

Both Goettsch Partners and MKA had previous experience designing buildings with an upward flare from a narrow pedestal: Goettsch with its design for Sowwah Square in Abu Dhabi, and MKA with its work on Rainier Tower in Seattle. Leveraging this expertise and in close consultation with Clark Construction and GEI, they applied their knowledge to craft the innovative sloping four-story steel trusses that provide essential support for the expansive 28,000-square-foot floor plates within the tower.

Once again, space constraints presented a challenge. Amtrak required the erector's crane to have the capability of lifting 150% of the load—amounting to 130,000 pounds of precast concrete bridge girders—at a distance of 225 feet from the center. Unfortunately, the limited available space made it impossible to maneuver a crane of such size.

In a stroke of ingenuity, the Building Team turned to the river as an opportunity rather than a hindrance. "We decided to view the river not as a liability, but as an asset," remarked Phares. "We said, Let’s put the crane on the river, and let’s make it the biggest crane possible."

And that's precisely what they did. Clark Construction ingeniously linked together 31 Poseidon barges to form a floating platform. On this platform, they mounted a colossal two-million-pound Manitowoc 888 Ringer crane with the capacity to lift an astounding 1.3 million pounds at a time.

"We assembled the largest pieces that could be transported over the road, each weighing 60,000 pounds, and put them together on site like an Erector Set, sometimes into quarter-million-pound assemblies," explained Phares. With the mammoth Ringer crane in operation, the erector, Chicago Steel Construction, effortlessly positioned the massive trusses into place. Phares added, "We attracted quite a crowd on the street and on the bridges when we did that."

‘the Riverwalk we created has become one of the most heavily traveled areas of the city. ’

— Chris Phares, Clark Construction Group

This river-centric endeavor necessitated seamless cooperation from multiple key entities, including the city, the Coast Guard, the Army Corps of Engineers, and the Metropolitan Water Reclamation District.

"Without that level of cooperation, we’d be looking at a big hole here," emphasized Erik Harris, AIA, CDT, Associate Principal at Goettsch Partners.

The team addressed the imperative aspect of the structure's capacity to withstand wind forces and minimize sway at elevated levels—a critical factor for occupant comfort, as noted by Chmielowski. They opted for high-strength, high-stiffness concrete to fortify and rigidify the core of the structure.

Furthermore, the Building Team devised 12 strategically positioned water-filled tanks, arranged in groups of three on the roof, serving as a tuned liquid-sloshing damper. Post-construction, MKA diligently monitored the dynamics of the as-built structure to ascertain the most effective water height. It was determined to be three feet, five inches, deviating from the initial estimation of four feet. "Now the tanks are perfectly attuned to how the building responds to wind," remarked Chmielowski.

In totality, the innovations introduced by the Building Team, such as the use of bolted connections in lieu of welded ones for the steel members, resulted in a reduction of 60,000 labor hours and a cost savings of $3 million, according to Clark Construction

 

Precertified LEED Gold (Core & Shell), 150 North Riverside was also the first trophy property in Chicago to be certified Wired Platinum for excellence in technology infrastructure. The Class A+, 1.2 million-sf structure was 85% preleased at opening. Investment banker William Blair & Co., Hyatt Corporation, and Navigant are among the gold-star tenants.

‘Minimizing the number of piles we had to dig was a huge win.’  

— Robert Chmielowski, MKA

“We don’t build monuments to ourselves,” said Riverside Investment & Development’s Executive Vice President, Anthony Scacco. “We build buildings that address the business needs of our tenants, specifically floor-plate efficiency, amenities, technology, and building infrastructure.”

It would seem that, in more ways than one, 150 North Riverside has really penciled out.

 

Building Team – Submitting firm, general contractor Clark Construction Group–Chicago Developer Riverside Investment & Development Co. Architect Goettsch Partners Structural engineer Magnusson Klemencic Associates MEP engineer Cosentini Associates Geophysical consultant GEI Wind studies RWDI Landscape architect Wolff Landscape Architecture 

General Information – Size 1.2 million sf Cost $270 million Construction time September 2014 to January 2017 Delivery method CM at risk