February 04, 2012

ACA Structural Member Styles - Part 3

First Article in the Series (Structural Member Catalog)
Previous Article in the Series (Structural Member Wizard)

Manually Created Structural Member Shapes
For those times when you want to create a Structural Member Style that does not have a standard cross-sectional shape, you will need to manually create the Structural Member Shape Definition and then add it to a Structural Member Style.

If you enjoy working from prompts on the Command: line, then you can use the
-AecsMemberShapeDefine command to do so. I find it easier to use the Style Manager, so that is the method that will be shown here. Before we dive into creating a custom Structural Member Shape Defintion, lets take a look at one, so we understand how it works. Structural Member Shapes support three levels of detail: Low Detail, Medium Detail and High Detail. Low Detail graphics can consist of lines, arcs, cirles or polylines. The image below shows the W24x76 Member Shape Definition (created from the Structural Member Catalog in Part 1 of this series) on the Design Rules tab in the Style Manager. This tab features a viewer pane that shows the cross-sectional geometry associated with this shape. Selecting Low Detail in the upper right corner highlights the Low Detail geometry in green; the Medium and High Detail geometry remains visible in the viewer, in white. A small "x" indicates the insertion point for the shape. As always, click on any image to see a full size version. If your browser replaces the current page with the image, use the Back button to return here.
Low Detail is intended for small-scale drawings, such as overall floor plans, where representing a wide-flange shape by three lines would be an appropriate level of detail.

The Medium and High Detail graphics have to be closed polylines, splines, elipses or cirlces. You can have more than one of these objects, but they cannot intersect each other, nor can they self-intersect. The Medium Detail graphics for the W24x76 Member Shape Definition consists of a single closed polyline showing the overall size and thickness of the web and flanges, and is appropriate for medium scale representations.
The High Detail graphics for the W24x76 shape also consist of a single, closed polyline, but differ from the Medium Detail graphics in that the fillets between the flanges and the web are shown. This would be appropriate for a large scale representation of the shape.
Each Structural Member Shape Definition must have Medium Detail geometry assigned. The Medium Detail geometry will be used for shapes where geometry is not specified for the Low Detail and/or High Detail conditions. For simple shapes, such as a circular column, assigning geometry to just Medium Detail may be appropriate. A square shape (with a side of 1'-0" for imperial units or 300 mm for metric units) is initially assigned when you create a new Structural Member Shape Definition, so be certain to replace that with the desired geometry. In the out-of-the-box Display Representations for Structural Members, the Structural Member Shape is used for the "Visible Comp n", "Hidden Comp n" and "Component n" Display Components, where n is an integer from 1 to 10. (Structural Members offer display control for up to 10 different components.) The Display Representation that have "Low" in the title use the Low Detail shape. The Display Representation that have "High" in the title use the High Detail shape. All others use the Medium Detail Shape. ("Logical" is a special case, which does not display any of the shapes.)

In the following example, a Structural Member Shape Definition will be created for eventual use in a Structural Member Style that will represent an architectural column cover. A simple circle will be used to represent the cover for Low Detail. In Medium Detail, two circles will be used to show the outside and inside faces of the cover. For High Detail, a closed polyline will represent the detailed profile of the cover. You will need to create the necessary geometry for your shape first, then assign it to a definition.
On the Manage ribbon tab, on the Style & Display panel, select the Style Manager tool. In the left pane of the Style Manager, expand the Architectural Objects and Structural Member Shape Definitions nodes under your current drawing and then select the Structural Member Shape Definitions node. In images below, I have selected the Filter Style Type tool (funnel icon) in the toolbar at the top of the Style Manager dialog to show only Structural Member Shape Definitions. In the right pane, right click and choose New from the context menu. Enter an appropriate name for the new definition - the example definition is called Fluted Column Cover.

In the left pane, select the name of the new definition. Select the General tab in the right pane, and add a more detailed description and, if you want, notes for this definition.
In the left pane, select the Design Rules tab. Take a look at the upper right corner, in the Shape Geometry area. The caution icons in front of the Low Detail and High Detail choices indicate that no geometry has been assigned. As mentioned above, there is already default geometry assigned to Medium Detail for the shape, and the preview window shows the default square shape.
To assign the right geometry for Medium Detail, make certain that Medium Detail is selected in the Shape Geometry area, and then select the Set From button. This will temporarily hide the Style Manager dialog, and, at the Command: line, prompt you to "Select a closed polyline, spline, ellipse, or circle for an outer ring:". Select the outermost geometry ("ring") for Medium Detail.
After selecting the outer ring, you will see the prompt "Insertion point or [Add ring/Centroid]:". Selecting an insertion point or choosing the Centroid as the insertion point will end the ring selection process. In this example, Medium Detail has a second ring, so choosing the Add ring option is appropriate. Continue to choose the Add ring option and select rings until all rings have been selected, and then select an insertion point or use the Centroid option to set the insertion point at the centroid of the selected geometry. This will bring the Style Manager dialog back on the screen, with the newly selected geometry displayed in the preview window.
If you have Low Detail and/or High Detail geometry for your shape, select the Low Detail or High Detail item in the Shape Geometry area and repeat the process of selecting the Set From button and following the prompts. Low Detail will not ask for an outer ring, just lines, arcs, circles or polylines and will not offer Centroid as an option for selecting the insertion point. Make certain that the insertion point for each detail level is the same, relative to the selected geometry. The image below shows the completed Fluted Column Cover Structural Member Shape Definition, with High Detail selected.
You can create a single-shape Structural Member Style that uses your new shape by selecting the Create Style button on the Design Rules tab. The default name for the Structural Member Style will be that of the Structural Member Shape Definition; you can edit the name if you want.
The image below shows an instance of the generated Fluted Column Cover Structural Member Style with the Masonry.Stone.Travertine.Cream Material Definition applied, in Realistic View.
Next article in the series (Manually Created Structural Member Shapes - Fun Facts )


Anonymous said...

Can structural members be used for sheet goods such as corrigated metal used as the skin of a quanset hut? would the process be the same?

David Koch said...

I suppose it could. You would have to define the profile as the cross-section of the corrugated material, for the width of an entire sheet. You could create an polyline arc that follows the path of a section through the Quonset hut and apply the Structural Member to that, to get the arched shape.