Trees of Steel

You know you can model anything with a good BIM software solution. The material used doesn’t matter, or the high level of structural complexity that mimics the organic – the structures of nature.

Three advanced Tekla modelers used BIM to grow trees of steel. Here they are.

Supertrees at Gardens at the Bay

The Supertrees stretch their steel and concrete trunks and canopies in the middle of genuine greenery. Gardens by the Bay in Singapore house conservatories and themed gardens, while at the center of attention are the 18 Supertrees, between 25 m to 50 m high. These trees generate electricity: Some treetops have solar cells generating power for the conservatories below. A 128 m long suspension bridge links two of the taller trees together and allows visitors to soak in the green view from 22 m above the ground.

Steel is a critical component of the entire project, and the steelwork was the responsibility of the Singaporean company TTJ Design and Engineering, which relied heavily on Tekla BIM software for the entire project. They worked closely with the architects and structural construction consultants to fabricate the parts needed for the Supertrees.

The geometries of the canopies are complex: The interlocking branches at the crown of each tree form a delicate network of steel tubes encircled by a stainless steel cable that pulls the structure together. To reduce the weight of the overall structure, the steel in this canopy is very thin, sometimes only 3.2 mm thick. As a result, just 920 tons of steel were used to build the 18 Supertrees.

At the factory, shop drawings and Tekla models helped to visualize the structures, a vital step given the complex geometries. The parts were preassembled at workshop, blasted and painted, then assembled on site to form trees again. Overall, the project took two years to go from the design office to the actual structures on the ground, ready to welcome the first visitors.

That’s pretty fast for growing a massive tree.

 

The Treehouse

Who did not want a treehouse as a child? Some go reach their dreams in their adult lives. This treehouse is a lifelong dream of its owner, who uses the 125-ton building as a guest house.

Detailing Group, Inc, USAutilized Tekla Structures as the design contains many complexities that were extremely difficult to manage. Outside of the platform framing for the houses, there are no right angles or straight edges. All but a few of the plates at the miter connections of the pipes are ovals. Agreeing on the accuracy of the Tekla model, all plates were burned from NC files with little to no information on the part drawings.

 

Mutant Trees - Shannon Public Art Presentation

The Mutant Trees are eight 15-meter high trunks of steel with surfaces comprised of triangular plates and supporting internal skeletons of tubes. Designed by Chris Doray studios and realized by Apex Structural, this small grove was one of Tekla Global BIM Awards winners in 2015. It is set for permanent exhibition at the Shannon Wall Center Kerrisdale, in Vancouver, Canada.

At Apex, the Mutant Trees project started with the artist’s visual 3D model. The initial Building Information Model included only the exterior surface consisting of over 500 triangular plates, and Apex easily located and modeled the hundreds of work points required to layout the surface plates.

Then, with consultation from the fabricator, Apex designed the internal skeleton structure of straight pipe tapered as required through the trunk of each tree and involving diaphragm or rib plates supporting the exterior. A similar system in smaller scale was repeated at each branch.

Organic shapes are definitely complex to turn into steel structures. Although the total number of fabricated parts was less than 650, the detailed model has over 6,000 objects.

Being a tech-savvy company, Apex developed two applications using Tekla Open API to make the trunks efficiently. One app collected all the exterior work points for modeling the surface plates, while the other was used to fit the exterior surface plates to each other, doing the seam cut between the edges of the selected plates and adding chalk marks to the surface for alignment.

 

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