The primary tower footprint is a rectangular form that has been skewed on the short side by pushing the northwest corner south in order to make the tower ends parallel to both Market and Filbert Streets. Additionally, the east and west faces of the tower are skewed to 36th Street. Managing building drifts was a major concern.
Another challenge was optimizing column locations to generate a desirable layout at residential floors while keeping the parking layout reasonable down below. The target was minimizing the amount of transfers.
The tower is a cast-in-place, two-way flat plate structure with a shear wall – frame interactive system for lateral load resistance. Shear walls around the core are located in the southern third of the building’s length with an east-west oriented shear wall in the northern third of the building to help minimize building twist under lateral loads, in addition to resisting lateral loads. Shear walls resist approximately 85% of the total lateral loads with frame action resisting the balance of the lateral load and helping to minimize building drift. The tower structure is supported on drilled piers at the columns, with a drilled pier supported grade beam and mat foundation at the shear walls.
A shear wall system was utilized for lateral load resistance. Sloping columns were incorporated between levels four and six to optimize the column locations for the parking layout below, while maintaining the desired column layout for the residential levels of the building, without the use of transfer beams below level six. Some columns slope in toward the building center line, while others slope outward. The alternating slopes necessitated the design of portions of levels four through six slabs as tension ties and compression struts in the same floor plate. Unbalanced loads in the plane of the floor slabs from the sloping columns were transferred to the shear walls through diaphragm action.
The retail level is a single steel-framed structure with a slab on metal deck roof level designed for future occupancy as an assembly usage. The retail portion of the building occupies the triangular area between the east face of the tower and 36th Street and is laterally braced by the tower.
The project was designed to achieve USGBC LEED Silver Certification.