Lesson 1: The Theory of Physical and Analytical Objects

Autodesk® Revit® Structure is a Building Information Modeling (BIM) application. All elements of the structural model are controlled by one unifying, underlying database that controls the entire physical and analytical model. Bidirectional associativity of the two structural models means a change to a physical object in one view changes the associated analytical object.

With BIM, we endeavor to capture, preserve, and reuse information for downstream applications. The benefit of this approach is higher-quality output and greater productivity with less effort (less cost). Revit Structure elements are controlled through parametric relationships between the physical and analytical members. For example, the analytical column is typically centered in the physical column geometric center. When you move the physical column, the analytical column moves as well, keeping its relationship to the physical column’s geometric center.

In Revit Structure, an analytical model is a simplified 3D representation of the full engineering description of a structural physical model. The analytical model consists of those structural components, geometry, material properties, and loads that together form an engineering system. Revit creates the analytical model automatically while you create the physical model, and you can export to analysis and design applications. 

In the following illustrations, the left view represents the physical model, and the right view represents the analytical model.

Figure 4.1: The physical model is on the left and the analytical model is on the right.

From the Structural Settings dialog box, choose the Analytical Model Settings tab to adjust how Revit Structure performs certain tasks on the analytical model.

Figure 4.2: The Structural Settings dialog box.

Automatic Checks: When enabled, automatic support checking provides a warning when a member is not supported. This setting is useful when most of the structure has been modeled, and you want to know if changes made to the model cause elements to become unsupported. Note: Enabling this setting during the early stages of a project will show a significant number of elements unsupported during model creation and can be misleading and unhelpful. 

Tolerances: Set tolerance limits for horizontal and vertical analytical model automatic adjustment. For more information, see Revit Structure Help for Automatic Adjustment of the Analytical Model (Auto-Detect). 

Revit Extensions & Robot

Autodesk Revit Extensions for Autodesk Revit Structure 2013 software provide a full range of benefits to enhance the software. Users of these extensions can benefit from their ease of use, helping them be more productive and agile while working on projects. For this unit we will specifically address the Autodesk Robot Extensions used in Revit Structure.

Autodesk® Robot™ Structural Analysis Professional software (Robot) is a feature-rich structural analysis and design software application capable of modeling and analyzing virtually any type of structure, no matter how advanced the geometry conditions. Robot is an ideal analysis companion for BIM software, and it links with Revit Structure. Using Robot enables Revit Structure users to directly analyze their models without oversimplifying or interfering with the 3D building model to satisfy the restrictions of their chosen analysis solution.

Historically, the workflow for design engineers involved interpreting architectural drawings and making their analytical model from these drawings, constantly checking and rechecking the correlating models. The finite element model from the engineer typically runs on its own platforms and does not interface with any BIM software. Autodesk revolutionized this process by introducing Robot and continues to improve on the robust link between Robot and Revit.

These extensions provide a vehicle to perform less complicated calculations in Revit, as well as producing professional reports for documenting the work. Not only does Robot interface with Revit but it links with many other software applications using a technique known as Interoperability. This enables models, or fragments of models, to be seamlessly moved on a common platform, ensuring the finite element model is the exact same as the physical model. The robust link creates a platform where you can model elements and conditions in whatever software is easiest to use and provides enough options for more complicated tasks. The following exercises highlight only a few of the many extensions available to Autodesk® Subscription customers. Learn more about Revit Extensions.


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