Aluminum Stair Stringers for a Helical Staircase

Early in January 2017, a company from Puerto Rico gave us a call to talk about the aluminum stair stringers for their helical staircase. The company was planning to make a helical staircase for ‘Birth of a New World’, a Christopher Columbus sculpture made by Zurab Konstantines dze Tsereteli. Tsereteli is a famous Georgian-Russian painter, sculptor, and architect known for large-scale and at times controversial monuments like the ‘Tear Drop Memorial’ pictured below, located across from Liberty Statue in New York City.

Tear Drop Memorial
Tear Drop Memorial

The Christopher Columbus ‘Birth of a New World’ statue was originally intended to be a donation to the United States to mark the 500th anniversary of Columbus’s landfall in 1492. After being turned down by several US cities, including Columbus, Boston, Cleveland, Fort Lauderdale, Miami and NYC, the statue was finally offered to Puerto Rico where Columbus arrived in 1493.

Birth of a New World Statue
“Birth of a New World” Statue

After this little history briefing, let’s discuss the details of the aluminum stair stringers used for the staircase leading to the ‘Birth of a New World’ statue. The staircase is in the center of the statue and spirals upwards. The statue itself is located by the ocean. In order to avoid corrosion issues, the customer chose to use a 10-inch aluminum channel made out of 6061 aluminum. This represented a challenge given the characteristics of forming aluminum stair stringers. Following CMRP’s engineering recommendation, the aluminum material thickness was increased to 5/16 help prevent deformation of the flanges.

Another big challenge in this project was the placement of the stair itself.  The circular wall within the statue was only 6-feet in diameter.  Within this space, the customer needed to fit an inside and outside aluminum stair stringer, going up 3 floors, each 13-feet high.  That implied an inside stair stringer with only 2-foot 2-inch internal radius with 52° of pitch.  In addition, outside stair stringer would run only 1-inch away from the concrete wall which required extremely accurate rolling/forming operations.  The job being all the way in Puerto Rico would give us no room for inaccuracies, the aluminum stair stringers had to be perfect.  As you can see from the pictures, they were!

"Birth of a Nation" Staircase
Helical Aluminum Stair Stringer
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