We call these structures “Basket Columns” to aptly describe both their form and function. These structures are shaped like baskets (form) and they are holding everything up (function)! This impressive architecturally exposed steel structure stands in the heart of NYC’s Financial District. As the entryway pavilion of the World Financial Complex, and home to the headquarters of Brookfield Properties, this awe-inspiring structure has more than 70,000 pedestrians walk between these basket columns each day. The central supporting, two spiraling steel basket structures rise 55 feet from the ground to hold up the roof, creating a transparent jewel box that serves as the grand entrance.
This is a shining example of how we brought an architect’s vision to life. With the architect’s vision in mind and the structural drawings in hand, we set out to figure out a way to actually build the structures. Always trying to incorporate the AESS flow, we fabricated and installed the architecturally exposed steel structure supporting a curved roof structure, complete with pre-tensioning for glass installation. We also machined, painted, and erected the structures.
This type of complex project definitely increases our adrenaline and creates a few gray hairs. It took a great deal of ingenuity and skill to make the fabrication and assembly of the ‘basket columns’ look like a thought out, yet simple process.
The level of fabrication and finishing was highly demanding on this project as all connections that are exposed needed to be connected in the field. The balancing of cambering and pre-tensioning the roof structure also created challenges to ensure integration with the finishing glazing elements.
Each structure is divided into five sections horizontally. When we had the first three sections assembled on the shop floor, the architect stood inside and looked up. With the architects permission, we deviated from his drawings because we felt that there was a more effective way to fabricate to meet his intentions. He commented that he was amazed at how closely the structure matched his vision with the integrity of his intentions making it through the engineering and fabrication process.
One of the biggest engineering challenges on this project was working with a spiral structure that meets a roof and has to be evenly tensioned, while predicting where everything would go from a deflection point of view. We had to use new approaches to hide where the bolts met the ceiling to maintain the integrity of the AESS.
Working within the congestion of downtown Manhattan made site logistics a challenge. The project also required a great number of players to come together in a coordinated way – including the Port Authority and a multitude of trades. We were involved at the preliminary stages which gave us a good perspective on the project and input on the design development.