Datasheet

elements
|
17
project they will become fixed to the datum elements. These basic modeling constraints then
become anchors for objects so that if you need to change a bay width or the story-to-story height
of a level those elements will also move correspondingly. For example: beam elements placed in
a third floor plan view are associated with that datum. Changing the elevation of the level will
take the beams along for the ride as they are defined as belonging to that level. This makes floor-
to-floor clear height adjustments quick and accurate.
Datum elements are an essential part of a constraint-based modeling system and are funda-
mental to how you will assemble and edit the design.
View-Specific Elements
View-specific elements are used to annotate and detail specific views of the model for the cre-
ation of your construction documents:
Annotation Annotation elements include text notes, tags, keynotes, dimensions, spot eleva-
tions, spot coordinates, and symbols. These elements play a critical role in translating the
model into construction documents. Unlike simple annotations found in other platforms, the
majority of the annotation elements in Revit Structure have a great deal of intelligence. Tags,
for example, are annotations that display specific parameter values contained in the model
elements. Change the size of a beam in the model, and all tags that you have already placed
will be updated automatically. Adding text is also a view-specific element (see Figures 1.14
and 1.15).
Detail Detail elements pick up where the model elements leave off. Some items are not
worth the time, effort, or performance overhead to model and can easily be handled with the
addition of simple 2D line work or by adding 2D detail components, such as to a section cut
through the model. These elements are used to complete in 2D the areas that are not mod-
eled but whose display aids in showing design intent. For instance you might add 2D earth
hatching around a foundation footing.
How Much Should I Model?
How much should you model and how much should you just add in 2D?
You need to ask yourself this question quite often as you proceed with modeling your project. You
might model the columns but not model the base plate and bolts in your project if you work for a
design engineering firm. In that case, modeling a few typical cases of various connection types will
be sufficient.
On the other hand, if you work for a detailing or construction management firm, you might have to
model every piece in the structure. The scope and extent of your model building depends on the docu-
ments that will be derived from it, as well as the BIM solution you are trying to achieve.
The bottom line to knowing how much to model in your project is that you must maintain the essential
integrity of the model by creating and maintaining the necessary elements to suit your purposes.
84404c01.indd 17 10/23/08 1:58:39 PM