"Free Form" Modeling in RAM Structural System V14.03

by Josh Taylor

Solutions Discussed: Modeling of Concrete-Framed Buildings

Products Discussed: RAM Structural System V8i, SELECTseries 3, V14.03


For some building structures, particularly concrete structures utilizing two-way slab action, the designer/drafter can create an analytical model of the structure most effectively when allowed to model in a "free-form" sense. That is, just let the mouse go where desired and add elements wherever the user clicks. This is in contrast to a more rigid modeling environment where the cursor is "allowed" only where dictated by snapping points enforced by the program, such as snaps to grid systems or elements already placed in the model. While enforcing snapping points is critical to maintaining the geometric integrity of the analytical data (particularly when the data will have further use downstream, such as for producing drawings), structural elements common in post-tensioned and mild reinforced two-way floor systems (such as band beams, drop panels, spandrel beams, and floor cutouts) can often times practically be modeled only if the user can form shapes freely without being overly constrained. While these two concepts are seemingly at odds with one another, RAM Structural System provides an effective middle ground for modeling these types of structures.

The following procedure allows the user to set up RAM Modeler so that the cursor snaps to a uniform array of snapping points. The spacing, origin, and rotation angle of the snapping array may be chosen by the user.

Go to Layout -> Type -> Select.

 Create a Floor Layout that will be used solely for the snapping array we will create. We will call this Floor Layout "Background Grid".

After the Floor Layout "Background Grid" has been added to the list, select the Floor Layout. Go to Layout -> Grids -> Create/Edit...

 Type "Uniform" in the Grid System Label field and select "Add". Now edit this grid system by selecting "Edit Grids".

Create a uniformly spaced series of grids in both the X and Y direction. This is done by setting a Grid Label ("1" in this example, which will be automatically incremented), choosing a starting Grid Coordinate (0.0 in this example), setting the Grid Spacing (0.5 meters), and the number of Additional Grids to create (100). Since grid labels are not necessary for this purpose, we can choose to suppress the display of the labels by unchecking the boxes within the "Display label at:" group.

After creating grids for both the X and Y directions, select "OK". Now go to Layout -> Grids -> Select...


Associate the grid system "Uniform" with the Floor Layout "Background Grid" by selecting "Background Grid" in the upper list and then checking "Uniform" in the lower list.

Select "OK". Now when viewing Floor Layout "Background Grid", the grid should be visible.

Now let's set RAM Modeler so that this grid system will be visible on every new Floor Layout we create. Go to Options -> Reference Layout Types...

Select "Background Grid" from the Layout Types list. Make sure the only other item selected in the dialog is "Include reference layout types in full zoom".

Note that entities on the reference layout (in this case the snapping grids) may be dimmed by setting the Dimming Amount at the bottom of the dialog. This enables the formal project grids to be visually distinguished from the snapping grids.

 Select "OK".

 Go to Options -> Set Snap Points. Go to the Reference Layout Types tab and make sure only the Grids item is selected.

Now when we model, the cursor will snap at a uniform distance of 0.50 meters over the floor extents we have defined. This gives us the ability to draw freely, while still ensuring as little numerical noise as possible will be introduced to the layout.

Now let's begin the modeling of the actual structure. Start by creating a new Floor Layout (Level 1).

Let's start our modeling by drawing an arbitrary slab extent. Go to Layout -> Slab -> Slab Edge.

Now we can easily place columns, walls, slabs, cutouts, and loads to complete the floor geometry.

Note that since the snapping grid system exists on a reference layout, not the Floor Layout on which we are working, we don't need to worry about the grid system being transferred to downstream applications such as Structural Modeler or Structural DocumentationCenter. The snapping grid system will be seen only by RAM Structural System.