Thursday, May 16, 2013

Beyond the Building Envelope

When most of us think about curtain wall, we picture its traditional uses - completely or partially surrounding the structure of a building, or embedded as a linear element in another wall.  In modern architectural applications, curtain wall is now being used throughout a project to allow the inclusion of natural light, to match the exterior elements providing a visual continuity to the project, and to give a more open feel to a facility.  In this post we'll showcase the use of curtain wall as the elevator surrounds at the Anaheim Regional Transportation Intermodal Center (ARTIC) completed for Wausau Window and Wall Systems.


  The scope of the project consisted of the four walls that surround an exterior, two-story elevator including mullions, glass panels, metal closures, coping and trim around the elevator doors.  Excluded from the scope were the elevator doors, elevator structure, louvered panels and other panels not by the contractor. 

  As curtain wall projects go, the layout for this one was very straightforward.  The walls were straight and vertical and the grid line elevations were consistent.  The front wall had to accommodate the elevator doors and the peripheral panels on the back wall consisted of metal closures.  Both side walls consisted only of glass panels.  Once the walls were placed, the Grid Line tool was used to located the vertical elevations of the horizontal mullions and the centerline of the vertical mullions.  With a grid line selected, the Add/Remove Segments tool was used to remove segments and better define the door and door header features.

The glass for the surrounds is 1 5/16" laminated glass.  When working in the Curtain Wall Panel.rft family template file, we drew the profile in the Ref Level plan view and extruded it upward.  To cause the panel to meet, and terminate at, the mullions properly, the edges of the panel were aligned with the reference planes in the Exterior view.  The family was named and then loaded into the project.

The new panel type was applied to all panels in the project and then the Empty System Panel type was added selectively to create the areas in the enclosure that did not have a glass infill panel.

Each required mullion was created using the Drawing tools in the Profile-Mullion.rft family template file.  The mullions were designed so that the horizontal reference plane aligned with the exterior face of glass and the vertical reference plane bisected the mullion.  Each mullion was uniquely named and loaded into the project.  See the blog tutorials Custom Profiles and  Adding Mullion Profile Parameters to learn how to make parametric curtain wall mullions.

Using the Mullion tool, a mullion was assigned to a grid object then the mullion was selected, edited (Edit Type button in the Properties panel), duplicated and the new profile assigned to the mullion as the Profile parameter in the Type Properties dialog box.  This mullion was applied wherever applicable and the procedure repeated until all of the mullions were in place.

Closures, Breakmetal, and Trim
These type of elements were created as extruded Generic Objects with a Length parameter added to control the extrusion distance.  Each Length parameter was designated as an Instance Parameter so that every occurrence of the object could have a unique extrusion length if required.

Each family was loaded into the project and placed manually, using the Align command and dimensional constraints, and customized using the Length parameter.

Finally, the coping was created in two steps:  First the profile was created in the Profile family template and that was loaded into a new Generic Model family template where it was used as the Profile element of a sweep object.

After naming the file and loading it into the project and aligned with the curtain walls.

Curtain wall is being utilized in more and more locations in projects other than the building envelope and storefronts and, employing the same principals used in more traditional applications of Revit curtain wall objects, you can efficiently adapt them to fit your design needs.

Wednesday, May 1, 2013

Creating Parametric T and F Clips

Several curtain wall systems, particularly in storefront  and strip window applications, use T and F clips to anchor the system.  The clips are fastened to the building structure along horizontal run of the curtain wall with the vertical members placed as a sleeve over the vertical protrusions of the clips.  This allows for vertical movement of the CW, as the building cycles through its normal changes throughout the year, but holds the CW in-place laterally.

This exercise follows the procedure to create a parametric F clip and a similar procedure can be used to create a parametric T clip as well.  By making the elements parametric, one family can be used for several different sized elements and fewer families are used in your models.  The basic procedure is: Create a profile, add dimensions, convert the dimensions to parameters, load the family into a model.  Here's how we'll do it:

1.  In Revit, click the Application Button (the R button) > New > Family to open the New Family-Select Template File dialog box.

2.  Select the Generic Model Face Based template then click Open.  This opens the design environment for a generic model that is oriented to a selected face in the Revit file.  This is chosen over the basic Generic Model template so that the clips can be used at either the top or bottom of the curtain wall.

3.  Make the Front view active.

4.  From the Home tab's Forms panel, click the Extrusion button.

5.  Draw the F clip in the view using the Line tool from the Draw panel of the Modify | Create Extrusion tab.  It isn't important that the lines are the correct length.  It is important though, that the lines are horizontal and vertical (except for the chamfers) and that the shape is closed without any overlapping lines.

6.  The chamfers need to stay consistent and this is handled better in sketch mode better than with the final, extruded element.  Zoom into the one of the chamfered ends.  Add a dimension starting from one vertical line near a chamfer then place your cursor over the opposite end of the chamfer and tap the Tab key until the blue, circular grip appears and select that point as the other point for the dimension.

7.  Click the lock icon, you may need to zoom out quite a bit to see this, to lock the dimension.  Repeat the process for the remaining seven dimensions that define the chamfers.

8.  Click the Finish Edit Mode button in the Mode panel to finish the sketch.  The dimensions near the chamfers will disappear; they are only visible and editable when editing the sketch.  If an error dialog appears, indicating that there are open ended lines or overlapping lines, click Continue and then address these issues before continuing.  Profiles must consist only of closed loops to create extrusions.

9.  In the Properties panel, set the Extrusion Start parameter to -0'  1 1/2" and the Extrusion End to 0'  1 1/2".  This will produce an extrusion that is 3" wide.

10.  To ensure that the model is stable when adjusting the parameters, we'll lock the vertical and horizontal perimeter lines to the horizontal reference face and vertical reference plane in the template file.  Select the extrusion then click on the lower horizontal line, not the blue triangle that appears, and drag it to the horizontal reference face, and then release it.  You don't want to drag the shape handle because that will change the shape of the profile. 

11.  To lock the profile in place, with the profile selected, click the Align tool in the Modify tab of the Modify | Extrusion panel, click the horizontal reference face then click the lowest horizontal line in the clip.  The lock icon appears allowing you to lock the profile line/shape handle to the reference plane.  Because the plane is pinned in place by default, it, and the shape handle will remain in place.  Click the lock icon.

12.  Repeat the step with the far left vertical line, locking it to the vertical reference plane.  If necessary, with the Move tool active, click the Constrain option on the Options Bar to prevent the extrusion from moving vertically.

13.  Dimension your extrusion but omit the dimension from the right perpendicular leg to the far right end of the clip.  You cannot have a parameter that defines the overall length and also one for every element that contributes to define that length - this would result in an error stating that the model would be over constrained.  By omitting that one parameter, the distance from the leg to the end of the clip is determined by the overall length minus the sum of the other elements' length parameters.

14.  In the Plan view, add a chain dimension from one edge to the reference plan to the other edge.  Select the dimension then click the EQ icon that appears to force the dimensions to maintain an equal value.  Add another dimension for the width of the extrusion.

15.  Now it's time to substitute dimensions with parameters.  Select the dimension that defines the overall length of the clip.  On the Options Bar, click the Label button, currently displaying <None> and choose <Add Parameter...>.

16.  This opens the Parameter Properties dialog box where the parameters are defined.  Make sure Family Parameter is selected as the parameter type, give the parameter a descriptive name and choose Instance as the type of data.  We prefer not to use spaces or hyphens in the Name field as they can result in errors when computing values in tables. 

17.  Click OK to create the parameter.  The parameter replaces the dimension in the view and has a default value the same as the dimension.

18.  Repeat steps 15-17 for the remaining dimensions, including the dimension in the Plan view.   Be sure to select Instance every time; each time the Parameter Properties dialog box is opened, the Type option is selected by default.  In this case, both legs are to maintain an equal length so a dimension is added to the other leg, then, with the dimension selected, the same parameter is selected from the drop-down list.  When that parameter is modified, the length of both legs will  change.

19.  Save your file then click the Load Into Project button to load it into a new or existing Revit file.

20.  In the Project Browser, select the clip type and drag it onto an existing face in the Revit file.  Move your cursor over another face to create a second clip; the base of the clip aligns automatically with the face that your cursor is over.

21.  Select each clip then adjust its parameter values, for each clip independently, in the Properties dialog box.

As you can see, with a little forethought and planning, you can easily make an adjustable, parametric clip that can meet many of your modeling needs.