Introduction to Modeling 101 in Robot Structural Analysis

Autodesk’s Robot Structural Analysis is widely recognized as a powerful finite element analysis (FEA) tool. Among its many features, it includes a built-in wind tunnel simulator, making it a standout choice for structural engineers. However, its complex and sometimes cumbersome user interface can present challenges, especially during the initial stages of use. Navigating through the analysis results also has its intricacies.

This blog covers essential modelling basics to help you get started smoothly. Here’s what we’ll address:

• Modeling beams & columns
• Modeling slabs
• Modeling arcs, curved elements and using the Revolve command

Before diving into modeling, note that the Project Geometry selection impacts the user interface and available commands. Choosing different geometry types might hide certain commands, which must be manually “unhidden” to use. For details on resolving hidden commands, see our blog: “Revolve Command Missing – Autodesk Robot.”

To change the Project Geometry after starting a project, navigate to the Geometry tab and select Structure Type. For this tutorial, we’ll use the Building Design Project Geometry/Structure Type.

Modeling Beams & Columns

When modeling elements in Robot Structural Analysis, it is best to define gridlines and levels beforehand. While this topic is not covered in this article, you can refer to Robot Structural Analysis: Getting Started – Grid & Levels for guidance.

To model a beam, first select the Beam command. In the Beam dialog window, you can choose the section type (Steel Beam, RC Beam, or Timber Beam) and add additional sections to your project as needed. You can browse multiple preloaded profile databases, including SAISC 2010. Once you are satisfied with the chosen member, click the Add button to add the profile to the project, making it available for use.

To add the beam to the model, go to the Beam dialog window, select the appropriate section, and place the beam by left-clicking anywhere in the model space. If you have grids and levels defined, your cursor will snap to intersection points. To add inclined beams, make sure to untick the Horizontal Beams checkbox.

The process for modeling columns is very similar to modeling beams. Add profiles in the same way, but you will need to set the Orientation to either Up (Z+) or Down (Z-) and specify the height. The orientation determines whether the column height extends upwards or downwards from the placement point.

Once your settings are finalized, place the columns by clicking once in the model space.

Modeling Slabs

To model a slab, first click on the Floors command. In the Floor dialog window, click the New Thickness button to define a slab thickness different from the default. In the New Thickness dialog window, adjust the thickness (Th) and assign a new label. You can also select a material other than concrete if needed.

After finalizing the slab thickness, click the Add button and close the New Thickness dialog window. In the Floor dialog window, select the new thickness and specify the model type—Shell is usually sufficient. To model an inclined slab, untick the Horizontal Slab checkbox.

Once satisfied with your settings, place the slab by left-clicking in the model space to define its boundary. Complete the placement by clicking again on the starting point of the boundary.

Modeling Arcs, Curved Elements and Using the Revolve command

To model an arc or curved elements, click on the Geometry tab, hover over the Objects pop-out, and select the Arc command.

In the Arc dialog window, define the placement and reference point order of the arc. Select the placement order of points to define the arc and place it in the model space.

Clicking the Parameters button expands the window to display additional options. To discretize the arc into straight segments, tick the Arc Discretization checkbox and specify the number of edges. A higher number of edges results in a smoother arc. Tick the Create Members checkbox to model a curved member. Place the curved member in the same way as an arc.

To modify the member profile, select the segment(s) and update the profile in the properties panel.

The Revolve command can be used to model domes and other elements. Start by modeling an arc to represent half of the dome’s cross-section. Select the arc, then go to the Geometry dropdown, hover over the Objects pop-out, and select the Revolve command.

In the Revolve dialog window, tick the New Object checkbox to ensure the created element is considered during the Wind Tunnel Simulation. The number of divisions affects the mesh quality, which is important for ensuring meshes intersect correctly when modeling overlapping elements.

Define the axis of rotation (usually at the center of the drawn element) and set the rotation angle to 180°. Click Apply twice to complete the operation.

Conclusion

With these basics in hand, we hope you find Robot Structural Analysis more user-friendly and feel confident in your journey to mastering the software.

Check out the extended version of this content and more on our YouTube page, where we cover these topics in a dedicated video: Modeling 101 in Robot Structural Analysis.

Still looking for answers? Start a discussion with other professionals in your industry!