Steel Shots: Changing the Climate

Brickell City Centre’s climate ribbon under construction and completed. 

Covering 150,000 sq. ft of space and housing a series of escalators and pedestrian walkways at Brickell City Centre in downtown Miami is the “climate ribbon.” Located three to five stories above street level, the glass-and-steel (mostly HSS) overhang creates an open-air “microclimate” for the low-rise shopping areas underneath, providing shade from the sun, collecting rainwater for reuse and harnessing the breeze off Biscayne Bay for a steady airflow of six to nine knots—and lowering the temperature by 15° to 20°.

Of course, the breeze isn’t always gentle in Miami, which has some of the highest wind loads in the country. As a result, the connection design loads in the lateral framing were quite large. The ribbon is framed with wide-flange members using 3-in. cap plates and more than two miles of HSS. While Schuff Steel Company — Southeast Division (an AISC Member/Certified fabricator) acted as the connection engineer, the overall framing schemes and member selection were dictated by the structure’s French manufacturer, and Schuff was to account for some of the most intricate connections in recent memory to address the assigned loads: 200 kips to 967 kips with average of 450 kips. In addition, 4-in. plates were used to address the wind loads of the ribbon so that it wouldn’t fly away in the event of a hurricane.

The climate ribbon concept is new to the United States. Developed by Cardiff University of Wales’s Chief of Architecture Science as well as architect Arquitectonica and designer Hugh Dutton and Associés of Paris, this is its first domestic incarnation. As such, the design was ever-changing, which resulted in multiple iterations of the interface connections and engineered loads throughout the course of the project. As the project progressed further into the fabrication and erection phases, the increase of loads continued to be carefully coordinated with all block team members in order to keep costs acceptable. This required the design, fabrication and the erection team to work closely through the changes, holding weekly model updates and coordination meetings with the general contractor, Americaribe Moriarty Joint Venture to ensure a successful project.

For more about Brickell City Centre’s climate ribbon and the entire multi-building project, see the article “Fluid and Flexible” in our current December issue (available now!).