ContractorAdjustable Forms, Inc. (concrete contractor)
The project is located at the intersection of N Carpenter Street and N Milwaukee Avenue in Chicago and consists of a 24-story mixed-use building totaling approximately 201,350 GSF. The ground floor includes resident amenities as well as two retails spaces of 3,550 SF and 3,050 SF. Parking is on Levels 1 through 4, an amenity deck and residential units are on Level 5, and the remaining levels are residential floors with penthouse units on Level 23.
The structural system consists of post-tensioned concrete flat slabs spanning between columns. The tower’s lateral system consists of a minimal number of strategically placed reinforced concrete shear walls. The foundation system utilizes belled caissons of diameters ranging from 2.5' to 4.5'.
The building consists of two large setbacks resulting in an eccentric core. This is further compounded by a 42-degree kink in the plan which allows the building to be placed in an oddly shaped site. As the project evolved, additional floors were added and floor-to-floor heights were increased. BASE worked closely with the owner and architect to minimize impacts on unit layouts and refined the design to continue with a single core building.
The Science and Design of Structural Engineering
Due to limited space available on the building’s footprint wedged between the existing buildings, the amenity deck is designed to cantilever 15 feet over the roof of the adjacent building. This not only increased the area of the amenity space but also helped to act as a fire separation between the two buildings. The podium level slabs on the north side of the building were cantilevered off long, thin blade columns placed between parking stalls. This allowed the caissons on the perimeter to be moved back to ease installation against the existing property. This also eliminated expensive grade beams that would have otherwise been needed if columns were provided at the property line.
In order to maximize the efficiency of the core walls, link beam penetrations were closely studied with the MEP consultant. Alternate routing of piping through shear walls allowed for link beam depths to be minimized resulting in higher ceilings in the lobbies.