Modeling Wind Forces with Tekla Structural Designer
When a timber canopy was proposed for a new building alongside London’s River Thames, the team used Tekla Structural Designer to ensure it would withstand the wind forces coming off the water. Their work won a Special Recognition in the 2020 Tekla Global BIM Awards.
Sometimes even the world’s largest and oldest cities surprise us with a piece of undeveloped land. Such was the case in the London borough of Richmond upon Thames, where the city council decided to look into developing a part of the riverside in the neighborhood of Twickenham. The idea was to breathe new life into this part of West London.
Working together with the Royal Institute of British Architects, the Richmond council opened a competition for ideas on how to develop the area. Cullinan Studio Architects was one of the firms to take part, submitting a proposal for a community wellbeing center with a timber canopy and reinforced-concrete frame. The company asked civil and structural engineering firm Mason Navarro Pledge to assess the feasibility of their proposal.
“Twickenham is such a beautiful part of London and I was surprised to find out there is that much free land there,” says Euan Stenson, a structural engineer from Mason Navarro Pledge who led the modeling part of the project. “We were tasked with creating the 3D model in order to determine whether the proposed timber design was structurally feasible in this environment.”
The building’s elaborate timber grid – resembling the shape of an oyster shell – was to be supported by steel tree columns and anchored down to a concrete roof deck. More than 2300 timber elements combined to give the canopy it’s 36-meter length and 12-meter height.
”We were the only competition team to propose the use of a timber grid shell structure. We wanted it this way to actively draw in the public,” says Stenson. “It meant using complex shapes that were aesthetically interesting, but also had to be structurally feasible and buildable.”
"Use of a timber grid shell structure meant using complex shapes that were aesthetically interesting, but also had to be structurally feasible and buildable.”
Euan Stenson, Structural engineer, Mason Navarro Pledge
Where wind meets wood
To do the 3D work, Stenson used Tekla Structural Designer – a software package that allows engineers to model the effects of wind forces upon a proposed structure. The team needed to ensure that the grid shell of the wellbeing center was stiff enough to resist the prevailing wind blowing in from the river.
“These types of structures can take off like a parachute if you’re not careful,” says Stenson. “A lot of people were surprised that we use Tekla Structural Designer for wood, but it’s very good at representing wind forces. We always use its wind force function if we’re designing a substantial building.”
“A lot of people were surprised that we use Tekla Structural Designer for wood, but it’s very good at representing wind forces."
Euan Stenson, Structural engineer, Mason Navarro Pledge
“One of the great things about the software is that it will show you deflection and displacement,” says Stenson. “In other words, it will show you how far something could fall over depending on wind direction.
“You just have to specify that a given panel is facing in a given direction, for example, and the software works out all the forces it will get hit by. It shows you around 250 different combinations of wind coming from various directions and on all sorts of axes.”
Winning public recognition
Over three long days, Stenson worked in Tekla Structural Designer to upgrade the design of the timber canopy with secondary elements to create a fully-functional wind model. Once the lateral load of the wind had been established, he was also able to re-examine the canopy’s reinforced concrete frame and supporting foundations. By understanding where the load transfer of the wind occurred, Stenson could highlight areas that required strengthening.
The team’s bid won praise for its creativity and was ultimately named as one of the five finalists in Richmond council’s competition. Members of the public appreciated how the stand-out design afforded views out across the river from an open yet covered space.
“This was by far the most complex and unusual structure I have ever worked on,” says Stenson. “It was a great experience and the special recognition from Tekla is a nice acknowledgement of all the hard work.”
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