Introduction
Describing things as “parametric” is something that has been thrown around a lot in the past few years and evokes some confusion with engineers. Some see it as something that is just for architects. Some see it as a software tool called Grasshopper or Revit families. Some just see it as something really complicated that has no relevance for structural engineers. In this article, we will help structural engineers better understand what is parametric design, and how structural engineers can take advantage of parametric workflows.
What is parametric design?
We will aim to give a summarized version of the history of parametric design from the perspective of engineers. Parametric design as it relates to structural engineering is something that has been around for a while now, since about the mid-2000’s and was made popular by architects. It was in this time period that programming languages such as Grasshopper were made mainstream to architects and the field blew up, as it gave the power to architects to create parametric computational models. What does that mean though? To do that, let’s break the term “parametric design” down.
To describe something as “parametric” means that you are defining something using variables. In parametric design, these are the variables of a design which are encoded into a computer language. Once the computer has all these input parameters of the design, it can then generate multiple permutations of the design. But when we say ‘design’, what do we mean. Let us be specific here – in most architectural practices, this usually only refers to the generation of the geometry of a design when we are talking about parametric design. A classic example of parametric design would be instead of drawing a cylinder by hand, one could use a coding language to define input parameters of ‘radius’ and ‘length’, and then quickly be able to generate any number of cylinders using this algorithm.
The benefits of this method for architects was twofold. First, in many cases, the computer can do things much faster than humans, so there were time savings to be had for the architects’ workflows which involve a lot of geometrical manipulation. Having a tool that allowed for better control of geometry like parametric design greatly assisted architects’ day to day work. Secondly, there was a lot of value to be added. Architects could now use this new, powerful tool to generate forms for buildings that previously would have been impossible. These new and interesting forms caught the attention of clients, meaning increase project work for architects who were using this technology.
Since architects were the pioneers in the space of parametric design, others have given extensive histories of parametric design specifically and parametric design shows up in part 3 of our own history of data in AEC that is related as well. Because parametric design was first made popular by architects, much of the content out there on the subject is geared towards architects. This is why it is so hard to find tutorials for parametric coding languages like Grasshopper for engineers – most tutorials you will find on the internet are created by architects, for architects. Given the large architectural focus of parametric design, can structural engineers learn and use parametric design? Yes!
Parametric design and structural engineering
Structural engineering involves geometry. Things like grid spacing, floor to floor heights, the shape of a core, or haunches of beams all related to the geometry of the structure or structural elements. The geometry of the structure has an impact on the stiffness of the structural elements, which in turn, affects the entire behavior of the structure, its reactions and therefore, what form (aka geometry) is needed to resist the internal forces. Seen this way, there is no clear boundary between geometry and structural engineering calculations.
Structural engineering tasks such as strut and tie models, core wall design, and load take downs are all calculation exercises structural engineers must regularly do that all involve geometrical inputs. As such, a mastery of geometrical information is something that any structural engineer needs for their day to day work.
So the common thread of parametric design to structural engineering is the need to master geometrical information. Parametric design involves using algorithms to control and create geometrical information and structural engineering can be seen as using geometrical information as inputs to engineering calculations.
Do Structural Engineers Use Parametric Design?
Yes! Although parametric design started very much as a tool used by architects, many structural engineers working with top tier architects have been using parametric techniques for years. Part of this is out of necessity. As we’ve discussed before, parametric design originally entered building design with architects who used it to create geometrically complicated forms. When engineers were faced with designing structures to support these complicated geometrical forms, it required a similar level of innovation on their part to contribute to these designs.
A classic first dabble in parametric design for structural engineers is the example of creating a parametric structure of some sort. This could be a parametric truss or parametric tall tower for instance.
Once an engineer manages to create a parametric model of the geometry of the structure, they can then connect that geometry parametrically into their engineering calculations. For instance, maybe you create a parametric structural model of a truss which not only generates the geometry, but also, applies cross sections, boundary conditions, and other calculation inputs such that a finite element model can be created. Not only would creating these calculations be faster, but also, because the models are generated algorithmically, it means that certain typical human errors could be eliminated as part of the parameters of the structure. Finally, the analysis of a parametric structural model like this can be automated such that the truss could be optimized for weight, stiffness, or any other variable. Adding these layers of engineering sophistication on top of the parametric geometry is the difference between computational and parametric design versus computational engineering.
What is Grasshopper and how does it relate to parametric design?
You may have heard about Grasshopper in reference to terms like “computational” or “parametric” design. Maybe you heard it from an architect or even from an increasing number of engineers who are using it for their work in design. Grasshopper is a visual programming language that can be easily adopted by civil and structural engineers. It originally was created by McNeel and Associates in 2007, and was quickly picked up by architects looking to push the envelope with their designs geometrically. You may have heard the term “parametric design” – Grasshopper was one of the original languages to make parametric design mainstream in architectural design. For more information on the pro’s and con’s of Grasshopper for engineers, check out our post of programming languages for engineers.
Conclusion
Parametric design is a powerful technique for handling geometrical information that every structural and civil engineer should know to accelerate their workflows and create better engineering designs. Benefits of knowing parametric design for engineers include:
- Save time on engineering calculations
- Reduce time spent on rework because of mistakes in geometry
- Better optimized designed
Most structural engineers are still not using parametric design techniques as part of their work, however, that is changing, as parametric and computational methods are quickly becoming a great way for young engineers gain a host of benefits and accelerate their career. If you want to use parametric design as a structural engineer, you’ll first need to learn a coding language. Grasshopper is one of the most used parametric design coding languages, and one that structural engineers can use to great effect. Check out our course on Grasshopper for structural engineers to find out more about how learning a bit of Grasshopper can benefit you as a structural engineer.