110 North Wacker

Constructed on one of the last available pieces of riverside real estate in downtown Chicago, 110 North Wacker is the tallest office tower built in Chicago since 1990. The 56-story building’s design maximizes Class A leasable space and corner office opportunities and showcases bright and airy column-free cantilevered interiors. Outside, a public space along the riverfront features a landscaped, covered walkway connecting two pedestrian paths and a park. Creative Collaboration Construction of this striking and innovative building was the result of a true collaborative effort between Clark, Riverside Investment & Development, and Goettsch Partners. Although 110 North Wacker occupies one of the best locations in Chicago in terms of accessibility and visibility, the site’s trapezoidal shape presented a challenge. The narrow site plan was incompatible with a conventional floor plate of 45-foot-wide expanses for office space flanking central elevator cores, while the city mandate for a publicly accessible riverfront further complicated scope. The design solution was to create an unusual stepped-center core, allowing for a 45-foot lease span on each side. Lateral wind resistance was achieved through an optimized system of two-story outriggers and edge trusses at the mid-span of the building. The lobby is framed by floor-to-ceiling glass, supported by a tensioned cable system featuring the world’s first building-integrated continuous load pin monitoring system, which is typically found in suspension bridges. During the design phase, the team also incorporated historical elements discovered during a landmark review of the site’s previous structure – the General Growth Properties building – by the Illinois Historic Preservation Agency and the US Army Corps of Engineers. While incorporating the salvaged metal panels created both aesthetic and building performance challenges, the team thoughtfully integrated the elements to seamlessly blend Chicago's past and present. Innovative Steel Construction 110 North Wacker boasts several innovative structural steel conditions, including a lower-level foundation wall, outriggers, a belt truss system, and a sawtooth shape on the west side of the structure. Most notably, the east foundation wall was constructed with an embedded steel truss system, which allowed vertical construction with structural steel to begin approximately six weeks earlier than a conventional design would have allowed. Even with that time savings, a key design challenge occurred when Riverside added two mid-level floors to the structure after Clark had begun steel construction at level five. This change, made without an extension of the schedule, created several conflicts with previously designed and coordinated scopes of work, including MEPFP, curtain wall, elevators, structural steel, and concrete. The team worked with trade partners and suppliers on redesign and procurement within weeks and their herculean effort allowed Riverside to add 70,000 square feet of leasable space without sacrificing the building's design aesthetic or performance.

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