New York, NY
Nemetschek Group Brands
Post-Tensioned Concrete Slabs, Concrete Shear Walls, Concrete Columns
Columbia University Medical Center
The Roy and Diana Vagelos Education Center is a 107,000-sf, 15-story state-of-the-art medical education facility located on the Washington Heights campus of Columbia University. The building serves as an instrumental tool in the team-based, problem solving-focused medical education that is provided to students. The tower includes the southern facing “Study Cascade,” which serves as a vertical campus, allowing students to learn and collaborate in an array of study, social and gathering spaces, including a 275-seat auditorium. In contrast, the northern elevation includes intentionally designed spaces that focus on specific functions, such as anatomy labs, cadaver examination rooms and a surgical simulation center. In totality, the building’s design allows for a wide range of learning experiences for the medical students.
About the Structure
While the Study Cascade provides students and faculty alike variable spaces for learning and collaboration, its design and layout created challenging vertical load path conditions for LERA, the structural engineer, to accommodate in their structural design. In order to minimize the structure’s impact on these spaces, the post-tensioned concrete floors were supported by a pair of inclined composite concrete columns that slope up from the foundation level to the 8th Floor and direct load around the column-free auditorium. An additional structural challenge included the need to provide long, open floor spans to meet the building’s programmatic requirements while also minimizing slab depth and deflection at the exterior all-glass façade. To accomplish this, post-tensioned concrete slabs (utilizing high-strength, 8 ksi concrete) were reinforced with bonded tendons, and cantilevered from the supporting inclined concrete columns. Void formers were also placed between the bands of post-tensioning in order to reduce the structure’s self-weight.
Michael Hopper, PE
Using ADAPT-Builder to calculate deflections precisely while taking into account the load sharing effects at the cantilevered slabs was absolutely critical to the design
To design the complex conditions of the structure, specifically in the Study Cascade, engineers at LERA utilized ADAPT-Builder. The software’s multi-story features were utilized to capture the load-sharing effects at the cantilevered slabs that are connected by single-story walls and ramps. Additional challenges arose due to the interaction between the all-glass curtain wall and the cantilevered post-tensioned slabs. Early in the project, the design team settled on acceptable long-term deflection limits (1 ¼” inches for cantilevers up to 26ft) that were then utilized to tune the bonded post-tensioned slabs. Detailed deflection contour plots from ADAPT-Builder were used to coordinate deflections in the slab with the curtain walls above and below, ensuring that the stringent performance criteria was satisfied. Overall, the flexibility that ADAPT-Builder provides allowed engineers at LERA to model and analyze complex conditions with confidence, ensuring proper coordination as well as an efficient design.