The Laurel is a 583,000-sf, 50-story high-rise residential tower on Philadelphia’s Rittenhouse Square. The project features an ultra-luxury mixed-use tower consisting of 65 condominiums and 184 apartments on top of a three-story podium with 44,000-sf of retail and dining spaces. Constructed of a cast-in-place concrete flat plate system with concrete shear walls, the building rises to 604 feet, making it the tallest residential building in Center City. A portion of the podium outside the tower’s footprint is a steel frame structure, while two concrete below-grade levels accommodate mechanical equipment space and parking.

To capture additional floor area above the adjacent historic building, the floors above were expanded to the west, requiring the edge columns to be located outboard of the locations below. “Walking columns” were utilized in four successive floors to achieve the transferred column location in the more than 40 floors above. There are considerable horizontal loads at the top of the uppermost and bottom of the lowermost columns. In tension strut locations, mechanically terminated tension drag struts were designed to drag these forces into the core. In areas outboard of the core, similar drag struts were designed, and then supplemental horizontal diaphragm reinforcing transferred the forces into the core.