# C+S December 2020 Vol. 6 Issue 12 (web)

for human errors that can, at worst, accumulate into costly miscalculations. • Simplify iterations. Addressing changes is much easier with parametric modeling than with a traditional 3D model, not to mention 2D CAD. Because adjustments to the model are based on the set logic and reflected throughout the entire design, it’s possible to iterate quickly while staying within a de- sign’s established criteria and constraints. • Innovate with ease. When the entire design can be created, managed and iterated as a whole, there are more opportunities to optimize the design pro- cess. Parametric design and modeling provide engineers with an easy way to rapidly test and discover options for making a project more cost-effective. When a better option is discovered, the changes can be implemented quickly and with ease. Getting Started Trying a new approach or workflow for the first time can be intimidat- ing. To give parametric design a try, consider these four steps: 1. Be willing to try something new. This may seem obvious, but it would be easy to read the word parametric and think, “this is too complicated” or “I’m not a programmer and I don’t have time to learn something new.” If you want to give parametric design a try, the full version of Rhino Grasshopper is free to evaluate for 90 days. What’s the harm in trying it out? 2. Take advantage of tutorials and instructional videos. The best way to learn is online through videos made by other structural engineers, tutorials, and forums. Some personal favorites: Grasshopper-Tekla Structures demo,

Grasshopper basics and these tutorials. It’s also fun to experiment with sample Grasshopper scripts which can be found with a simple Google search. 3. Experiment with a simple design. Start by experimenting with paramet- ric data for a simple design in Grasshopper and create output objects in a parametric BIM software. It’s not necessary to jump right in and learn using a complex bridge model. For example, build a simple wireframe structure, such as a portal frame, and use the line output as centerlines for the parametric BIM objects. 4. Get Organized. It’s important to know that parametric design and mod- eling require organization. Create notes and keep the script of parameters organized and well documented so that any project stakeholder can under- stand it a week, or even a month, later. With dynamic automation, increased accuracy, rapid iterations, and more resources for the design as a whole, the benefits of parametric de- sign are undeniable. While it can be used for any project big or small, it’s especially advantageous in complex structures with unconventional architecture. Using parametric design with constructible BIM-tools takes the modeling process to the next level and makes it possible to streamline work, create high-quality and constructible designs and deliver successful projects – totally model-based without drawings.

GABRIEL NEVES is Bridges Technical Manager at Trimble, Structures Division and Ministry of Bridges YouTube channel Content Creator.

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