Read about the creative problem-solving and teamwork required to bring this vibrant public installation to life while preserving its artistic integrity.
Novus Textura is a public art piece currently on display in downtown Calgary, adjacent to Bankers Hall at the heart of the primary pedestrian corridor, Stephen Avenue.
Recently, we sat down with Ian Washbrook, Principal, and Kirk Haugrud, Associate, to discuss the engineering of this vibrant, complex sculpture.
Thanks so much for sitting down with us, Ian and Kirk. Can you tell us a bit about this project?
Ian: Thanks so much for having us and absolutely. Novus Textura comprises a series of colourful straps woven through the existing Galleria Trees and underneath the skywalk bridge spanning Stephen Avenue here in Calgary. The piece spans an entire city block and is meant to represent new directions in the ongoing development of Calgary. It also represents the city’s history of innovation and resiliency through collaboration, bringing together a wide-ranging team to express its artistic vision.
Kirk: The vision for this sculpture was to rethink how the existing architectural trees could be turned into something more artistic. The artists Gordon Skilling and Jolie Bird recognized that the Galleria Trees look like the reed of a loom. This inspired the idea to weave brightly coloured fabric through the trees like thread to create an explosion of colour and life in Calgary’s downtown core.
Ian: We really enjoyed working on this project and hope as many Calgarians can enjoy it as possible. Unfortunately, as a temporary installation, the piece will be taken down in June of 2025. And we are certainly going to miss it.
What were some of the main challenges on this project and how did you overcome them?
Ian: To start, we first had to understand the condition of the existing Galleria Trees. Our team performed a LIDAR scan and a drone-based condition assessment to understand what type of load they could handle. This assessment allowed us to advise the artists on how to modify their plans appropriately for the straps.
Kirk: Next, we had to develop an accurate SAP model of the trees for analysis. As we had access to detailed shop drawings of the trees, we were able to create a 3D Rhino model of them. We also developed a custom parametric Grasshopper script to generate a SAP2000 finite element analysis stick frame model of the trees with over 100 non-prismatic cross sections. The Rhino model was then developed further into a 3D mesh model, which the artists used for 3D printing to aid in their visualization of the overall installation.
We also retained Gradient Wind Engineering to understand wind, snow, and ice loading on the trees and how the presence of large swaths of fabric would impact that loading based on our SAP model.
Ian: Finally, for this part, we advised the artists that the threads composing each strap should be twisted as that would reduce vortex shedding and fluttering of the threads. Gradient Wind came to a similar conclusion, and we ultimately specified a minimum of a full 360° twist for every thread.
Kirk: The second main challenge we encountered was how to weave the straps under the skywalk bridge. To solve for this, our team designed a subframe to be suspended from the bridge.
We specified a panelized system of thick wire mesh, spanning between purlins and girders, to which the artists could stitch their weave, ensuring that it would appear taut and flat.
The subframe was connected to the existing structure using clamps so that it could be installed and removed easily without damaging the +15 bridge. Our team designed most of the connections, including hidden grommet connections where the straps interface with the weave, and TEK screws for connecting purlins that could be installed through the weave.
Ian: We also had to develop a plan for how the straps would actually be woven through the trees. After deciding on a 3-inch-wide polypropylene webbing, we designed the straps as catenary cable elements using SAP, understanding that when it comes to catenary design, sag is extremely important. Taut cables can produce surprisingly large tensile forces under simple wind and ice loading.
However, the artists wanted the straps as taut and straight as possible. So we developed a compromise that incorporated a 1-meter-sag equal to 5% of thread length. Once we had achieved the desired sag, we were able to develop a solution for connecting the straps to the Galleria Trees. This involved steel forged rings with slots cut in them that were welded to the tree branches, as well as loops sewn into the straps that could slide through the slot.
Kirk: Finally, we conducted a LIDAR point scan to understand how long each strap needed to be. The LIDAR point scan captured all of Stephen Avenue as well as the trees.
In order to parse the results of that scan, which returned 180 GB of data, our team developed a Python script and used the open-source software CloudCompare to complete the point reduction process to 1/1000th the size. We then imported the point cloud into Rhino to develop a thread pathway model.
Using Grasshopper, we generated parametric cable elements that had end points mapped to the LIDAR scan data and could be quickly adjusted for different amounts of sag or connection points.
The artists ultimately based all their thread fabrication off this model.
Wow, the amount of creativity and problem-solving that went into this project is incredible and was well worth the effort. What was your favourite part of the project?
Kirk: Collaborating with the artists and the many other individuals involved in realizing this work. There was a lot of passion and care in the team to deliver an uncompromised vision, which made the project feel that much more rewarding. It also felt good to flex some problem-solving skills to deal with the many unique aspects of the project. Most of all though, I enjoyed being able to experience the final product, show it off to family, and feel confident that it would have a meaningful impact to many other onlookers.
Thank you so much for your time, Ian and Kirk. We appreciate your time in discussing Novus Textura.
If you’d like to learn more about this project, reach out to Ian Washbrook or Kirk Haugrud.
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