Hollow core

Last modified by Desi Borisova on 2022/01/27 11:38

Hollow Core module

Hollow Core is prestressed concrete slab, largely used in the precast concrete industry. IMPACT Revit contains a Hollow Core module, which can be found under the IMPACT tab. Hollow Core module is divided in four main parts, which help the user to draw, edit and change the settings of the Hollow Core elements.

See a demo video of the Hollow Core module on the link here


Insert Hollow Cores 

Once you press on Hollow Cores, a dialog window appears with two main tabs, called General and Endcaps

The General tab allows the user to select a Revit Hollow Core family, which has been already created and placed under the IMPACT Revit standard folder … \IMPACT15\Standard\1101\1101\Revit\elements\ hollowcore. The main geometry measurements of the Hollow Core are automatically loaded, once the family is chosen. Strand patterns are also shown, according to the ones created in the family. The user can choose between the available strand patterns in the drop-down menu. Changes in the strand patterns can be seen in the Hollow Core section picture, shown in the window, as well as in the table below.


Figure 1. Insert Hollow Core. 

After the family is selected, the user needs to select a boundary for inserting the Hollow Cores.  There are three options to choose between boundary selection:

  • Pick floor is an option that chooses already existing architectural or structural floor in the Revit model as a boundary for the hollow cores. If the floor has a slope, Revit IMPACT will also inset the hollow cores with a sloping surface.

  • Pick model lines gives the user possibility to draw Hollow Core with a boundary defined by model lines. This boundary selections makes it possible to draw Hollow Core with user defined non-standard shapes. Notice that if you choose Pick Model Lines option, you need to draw the lines in advance before pressing on Select Boundary.

  • Draw rectangular is perfect option to be used if the boundary of the Hollow Cores has a rectangular shape. The user does not need to draw the rectangular shape in advance.

If Support length needs to be defined, then its value can be written in the field, called Support Length. /Under development.

Placement defines how Hollow Cores are going to be placed in vertical direction in the Revit model. If the user selects Top, then the top edge of the Hollow Cores is going to be aligned to the level elevation, on which the Hollow Cores are inserted. If Bottom is selected, the bottom of the Hollow Cores is going be aligned to the current level elevation.

Pick insertion controls where the insertion of hollow cores should start. The user defines the insertion point by clicking on a certain point of the hollow core boundary. The insertion will continue in right direction from the insertion point, until it meets the hollow core boundary.

Pick direction allows the user to change the direction of the Hollow Cores, once the boundary is selected and a sketch of the Hollow Cores appears on the drawing. It is enough to press on Pick insertion and select one of the boundary edges, of the Hollow Cores must be rotated, before their insertion on the drawing. The orientation is changing in accordance to the selected Hollow Core edges.

Partial slabs are always marked with an arrow on the Hollow Core sketch and the user can control their insertion and placement settings. Partial slabs are not inserted in the model if the Inset box is left unchecked. Placement of partial slabs can be controlled with the help of the up/down arrows next to Location and the user can follow their movement on the Hollow Core sketch. IMPACT Revit shows the width measurement of each partial slabs in the sketch.

partial slabs.png

Figure 2. Draw partial slabs options.  

Endcaps tab allows to make settings for the geometry of the Hollow Cores left and right edges.  The user can choose between already created endcaps, or adjust the endcap according to the project needs. This function allows automatically generating surface recesses and holes. 

Clean cores setting controls the filling of the cores, which gives a possibility to fill the cores with concrete to strengthen the Hollow Core slabs, that require it.


Figure 3. Hollow Core endcaps 

Edit Hollow Cores

Once the Hollow Cores are inserted in the drawing, the user has the possibility to edit their geometry and strand patterns in Edit Hollow Cores.

Figure 4. Edit Hollow Core command 

Select the Hollow Cores in the drawing and click on Edit Hollow Cores. The same dialog window opens, where the user can edit the main geometry of the elements width, length and endcaps. It is also possible to make changes in the strand pattern by selecting another one from the list. 


Figure 5. Edit Hollow Core window 

Insert Hanger

Revit IMPACT has a function, that gives the user the possibility to insert hanger detail, if necessary.


Figure 6. Insert Hanger command 

Click on Insert hanger and select consequently the slabs, which needs to be supported, and the supporting slabs. A dialog window opens, where the user can select already created hanger families from the list. The two opposite corners of the recess must be specified, before pressing on OK to insert the hangers in the project.


Figure 7. Insert Hanger window

Hanger details can be edited by clicking on Edit in the lowest left corner.  A new dialog window opens, where the geometry settings as well as the placement of the hanger can be edited.  The user can change CIM family, decide core filling and edit the recess in the Hollow Core slabs. The Hollow Core sketch will change while the different parameters are set.

Figure 8. Hanger details 

Hollow Core settings

The settings of the Hollow Core family can be changed in the Revit family.


Figure 9. Hollow Core Settings. Active in the Hollow Core family. 

You can read more about all the setting the Hollow Core family in Hollow Core settings.

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