Friday, September 19, 2014

Controlling Embed Visibility Using a View’s Detail Level

In the building envelope industry, embeds are structural elements, cast into the concrete floor, and they bear the load of the curtain wall.  Companies, such as Jordahl and Halfen, make and supply cast-in channels that are often used as embeds and it is also common that project-specific embeds are designed.  In this tutorial, we will look at a method of displaying different elements of a custom embed depending on the Detail Level of the current view.

The embed that we’ll be using is made up of 6x8 angle, end plates to keep the concrete out, headed studs to tie-in to the anchor (the feature that connects the embed to the curtain wall), and rebar tails to increase the strength of the embed.

Why is it necessary to model to this level of detail?  In many cases, it is beneficial for clash detection and data extraction.  The size of the “box” and location/length of the rebar tails can identify conflicts with floor decking, columns, or other structural elements.  The appearance of the headed studs can ensure proper connection with the anchor and the elements, if created properly, can appear in schedules.

At larger scales, it’s important to see where the embeds are located, but the location and orientation of the rebar tails and studs is not.  These features may even become unreadable or blotchy.  At smaller scales, the appearance of the rebar tails and studs become more important and easier to distinguish.

To customize the visibility of the individual elements, we’ll start by selecting the headed studs then clicking the Edit… button for the Visibility/Graphics Overrides option.

This opens the Family Element Visibility Settings dialog box.  In the Detail Levels area, we uncheck Coarse and Medium to prevent the studs from appearing in any view that isn’t set to Fine.  

After clicking OK, we’ll select the rebar tails then repeat the previous procedure, this time unchecking only the Coarse option.

The embed is loaded into a scene and placed appropriately.  In this case, as is usually done in embed plans, the Bottom Offset and Level Offset values in the View Range dialog box are set to -1’-0” to allow the embeds to appear in the current view, rather than as an underlay.

As you can see, with the view’s detail level set to Coarse, only the angle and end plates are visible.

In a larger scale, the Medium Detail Level may be more appropriate.  This allows the rebar tails to appear in the view.

Finally, at a scale where the Fine Detail Level is best, the headed studs appear.


As you can see, by defining which elements are to appear at which detail levels, you can control how a single object appears in different views.  This also allows you to create objects with fine details that would be lost at larger scales while adding quality and accuracy at smaller scales.

Wednesday, July 30, 2014

Accurate Profiles Equal Accurate Curtain Walls

 The basic workflows for creating and assigning mullions to a Revit curtain wall are fairly straightforward.  You can either design a mullion type, with a specific mullion profile family designated in the Profile parameter, then assign that type to a curtain grid line or select an existing mullion on the curtain wall, duplicate the type, then assign a new profile to that mullion.  Profiles are assigned in the Type Properties dialog box.

In the mullion profile family file, there are two reference planes and both have their positions pinned by default.  At intermediate curtain wall grid lines, the vertical reference plane in the profile family is aligned with the grid line while the horizontal plane is aligned to the front of the curtain wall.  In jamb, head, or sill conditions, the edge of the profile is aligned to the edge of the curtain wall so that the entire profile is enclosed within the extents of the curtain wall.

The image below shows a 20’-0” long curtain wall with four vertical mullions in place.  The continuous dimensions, along the top and bottom, both add up to the total length of the curtain wall, but the first and last dimensions of each string are different.

What is causing the discrepancy?  The top string of dimensions is measuring to the center of the mullion as defined by the location of the vertical Center Of Mullion reference plane in the mullion family file. The bottom string of dimensions is measuring to the horizontal midpoint of the vertical mullion.  These should be in the same location, but in this instance, they are not.  Let’s take a look at the mullion profile.

As you can see, the mullion profile is not centered on the reference plane.  This is a situation that we’ve encountered, on occasion, when using content provided by third parties.

Why is a small dimensional inaccuracy a concern?  Mullions, anchors, kickers and embeds are usually aligned to their respective center lines.  If one of these is not located properly, then it may cause a clash at each occurrence which can add thousands of clashes to a project that would need to be addressed.
To remedy this, we can’t simply select the left-most line of the profile and change the dimension; this would result in a non-symmetrical and inaccurate  mullion.  Instead, we’ll delete half the profile, fix the remaining half, and then mirror the lines to complete the profile as shown here:

       1.       Delete or trim the side of the mullion that is shorter than the other.

       2.      Add and lock any horizontal dimensions that must remain constant.

       3.      Change the overall length

       4.      Select all of the lines (hover over one, press the Tab key, then click the left mouse button) then use the Mirror – Pick Axis tool from the Modify panel to mirror them about the vertical reference plane.

       5.      It’s a good practice to use a few lines as possible in your profiles.  The four short, horizontal lines that touch the vertical reference plane can be reduced to two lines by deleting one and stretching the other at both ends of the mullion. This will also eliminate an unnecessary vertical line in your elevations.

       6.      Save the family then use the Load Into Project tool to load the profile family into the Revit project.  In the Family Already Exists dialog box, choose either the Overwrite The Existing Version or Overwrite The Existing Version And Its Parameter Values option, depending on whether the profile has parameters included.

       7.      In the project, the dimensions measuring to the centerlines and the dimensions measuring to the midpoints are now equal.

Accurate curtain wall mullion profiles are essential to creating accurate curtain walls in Revit.  A little time spent ensuring that your profiles are correct at the beginning of a project can prevent headaches and reduce revision time later in the project’s lifespan.

Tuesday, May 13, 2014

Selecting Curtain Wall Components

Revit has specialized tools for selecting curtain wall-specific components based on the grid lines they are hosted by, their orientation, family, or the curtain wall host and this post explores those tools and explains how they are used.

Curtain walls, in Revit, are comprised of mullion, panel and gridline components.  These components can be selected individually by hovering the cursor over one or more objects, tapping the Tab key until the correct object highlights, then clicking the left mouse button.  Click here for a post on selecting specific curtain wall objects and some issues that may arrive.

 Like all objects in Revit, you can select the other object in the same family by right-clicking the mouse and choosing Select All Instances > Visible In View or Select All Instances > In Entire Project depending in the extent or requirements of the selection.  This can be used to change all mullions or panels from one family to another.

 To select all mullions, regardless of family, along a gridline, select one mullion on that gridline, right-click, then choose Select Mullions > On Gridline.  Your cursor must not be hovering over another object when you right-click or the context-specific menu will not show the Select Mullions option.

 All the mullions on the same gridline as the original are now selected.  You can use Select Mullions > On Gridline for both vertical and horizontal mullions

 This selection method also works when gridline segments are deleted by selecting the mullions on both sides of the missing span.

 Similarly, with a mullion selected, you can right-click and choose Select Mullions > Across Gridline to select all mullions that are parallel to the selected mullion and run between the same perpendicular gridlines.

 The other Select Mullions menu options include:

On Vertical Grid – Selects all vertical mullions on the current curtain wall.
On Horizontal Grid - Selects all horizontal mullions on the current curtain wall.
Inner Mullions – Selects all mullions that are not along the perimeter of the
                            current curtain wall (jambs, sills, heads).
Border Mullions - Selects all mullions that are along the perimeter of the
                              current curtain wall (jambs, sills, heads).
Mullions on Host - Selects all mullions in the current curtain wall.

Using any of the five methods listed above will deselect selected mullions if appropriate.

There are similar tools available for selecting curtain wall panels; however, they are slightly more restrictive.

After selecting a curtain wall panel, right-click (being sure not to hover the cursor over another object) and choose Select Panels > On Vertical Grid.  All vertical panels that are the same size as the original and run along the same vertical grid line are selected.  Revit will omit any panels that are not the same size.

Select a curtain wall panel, right-click and choose Select Panels > On Horizontal Grid.  All horizontal panels that run along the same horizontal grid line, even if they are of a different size, are selected. 

As expected, Select Panels > Panels On Host selects all the panels on the current curtain wall.

As you can see, there are several tools available to help you select Revit curtain wall components by family, vertical gridline, horizontal gridline, orientation or curtain wall.  I’m just waiting for the Select All Mullions Using The Old Die Designs And Replace Them With Mullions Using The New Designs button.  Now that would be helpful!

Monday, February 3, 2014

Why can’t I select my curtain walls in Revit?

Have you ever come across a situation where you can see the curtain wall elements in your Revit scene, but could not select them?  To make this a little more confusing, you could select the components of the curtain wall, but not the wall itself?  We have, especially when constructing the building envelope in files that were originally generated by someone else.  Fortunately, this is an easy fix.

Let’s take a look at the situation.
Zooming into a curtainwall, you place your cursor near the perimeter and expect the curtain wall to highlight as it usually does.

This time, the head mullion highlights, but not the overall curtain wall element.  Pressing the Tab key cycles the selection through the nearby curtain wall components, but not the host object.       

Trying to select the curtain wall with a selection window and filtering out everything except the wall itself seems like a solution but, as shown below, Walls are not shown as selected objects in the Filter dialog box along with the other objects.

What’s the problem?  It’s not the wall itself, but the Discipline setting of the current view.  With nothing selected, look at the Properties panel.  In the Graphics area, if the Discipline value is set to Structural, the curtain walls cannot be selected.  There are two solutions:  The first, and preferable, is to change the Discipline parameter of the view to Architectural or any option other than Structural.

The second, and not recommended, option is to select the curtain wall then, in the Structural area of the Properties panel, check the Structural option.  Curtain walls, by definition, are not load bearing and this solution may have ramifications regarding the structural design of the building.

We hope this information has been interesting and helpful.  If you have any questions regarding BIM and curtain walls, don't hesitate to ask.