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Coordinated and Accurate Concrete Detailing with Rebar Constraints in Revit

Revit provides tools for Structural Engineers and Detailers for modeling 3D reinforced concrete and generating quantities, shop drawings, and bending schedules in an advanced BIM environment. Revit enables users to design and detail reinforced concrete elements with clash prevention features that improve coordination in the preconstruction and site execution project phases.

Modeling tools in Revit allow Structural Engineers and Detailers to define accurate reinforcement for standard and non-standard shapes of building and infrastructure concrete elements.

In Revit you can use rebar tools to create reinforcement that reacts to changes according to your specified rules—and you can precisely adjust the results.

Shape driven rebars, like the name implies, have their geometry defined from rebar shape families that you can load or create from scratch in the project. These bars expand to fill the concrete host on placement and are automatically constrained to the concrete or to other bars (standard bars to stirrup bars).

REBAR SNAPPING TO COVER

For the concrete element to work as expected (corrosion resistance, etc.), it is very important for bars to respect the concrete cover.

When placing rebar—either directly or by sketching—the bars will automatically snap to the concrete cover or nearby bars. This behavior also applies when adjusting the bars by dragging individual bar handles.

Figure 1: Automatic snapping of the bar to the cover when sketching a rebar.

Figure 2: Automatic snapping of the bar to the cover when dragging an individual bar handle to the element cover.

Shape driven rebars snap intuitively to the concrete cover when you copy or move them (e.g. nudge, mirror, array, etc.). When you move or copy a rebar set, the rebar doesn’t snap to the concrete cover. By not snapping automatically, very small segment length adjustments are eliminated, and the rebar geometry remains consistent. This also prevents new rebar positions (or rebar numbers) from being created. In versions of Revit prior to 2020, a rebar would snap to the cover if closer than half the bar diameter from the cover.

Figure 3: Example – Copying stirrup (A) to produce 3 identical stirrups (B) without the segments snapping to the slightly varying concrete cover.

REBAR AUTOMATIC SELECTION OF CONSTRAINTS

Shape driven rebar segments are automatically constrained only to the concrete host faces that are in the range of each segment (i.e. the segment passes over the face). This ensures that bars do not connect to faces that are far away and subsequently react to changes of those faces. If desired, you can manually select any face (constraint target) parallel to the bar segment, even if it is not within range.

Figure 4: Example – Faces (1), (2), (3) are parallel to the bar segment, while (1) and (3) are also in range of the bar segment; of the two, (1) is closer, so it’s set as the auto constraint

The ends of the bars are automatically constrained to the closest (infinite) surface. The bar ends search for constraints to faces of the host or neighboring elements of the host to which that end belongs.

Figure 5: Stirrup ends automatically constrained to closest (infinite) surface

To learn more, please check the Revit for Concrete Structures YouTube playlist.

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