Deck Assignment Mode dialog

Used to assign deck or slab properties and define deck orientation for the area inside the slab edge definition.

Opens when:

Layout > Slabs > Deck Assign is selected
the Deck Assign tool is selected from the Slab Layout dynamic toolbar

Slabs are used in the program, for example, to define the distribution of Surface loads and to determine composite beam properties. If no slab is defined, no automatic tributary load distribution of surface or snow loads will take place. Also, there will be no automatic Live Load reduction, as the tributary areas will be undetermined.

Deck assignments must be made over all areas inside the slab edge boundaries except that for One-way decks it is not necessary to assign deck to the area between the perimeter beams and the slab edge itself. However, if no deck is assigned to that area, it will be assumed that the slab edge is non-composite deck, and the slab edge width will not be included in the calculation of the effective flange width for a composite beam. If composite deck (for composite steel beams) or concrete slab (for concrete beams) is assigned to the slab edge, that distance will be included in the calculation of the effective flange width. Note that in either case the member loads are not affected, they are calculated the same. Deck Assignments can be placed well beyond the slab edge, and will be automatically clipped to the slab edge by the program.

Overlapping Deck Assignments can be made. The last applied deck assignment takes precedence over any decks assigned previously (underneath it). Drop Caps follow this same rule, except that drop caps are always considered to replace all other decking.

The slab edge boundary should be input before decks are assigned. If the slab boundary is not completely defined, RAM Modeler will not display the decks. The DataCheck command can be used to obtain a report that lists any breaks in the slab edge and where those breaks are located.

Setting

Description

Slab Action

Select the load distribution system assumed in the slab or deck:

One-Way -
Two-Way

In some aspects the modeling requirements differ between the two. Because of the specialized nature of the One-way analysis, the modeling requirements for One-way decks are generally more stringent, as described below. In many cases the modeling commands are tailored to these requirements. Only One-way decks should be assigned to steel framing.

Two-way decks should never be assigned to areas of steel framing. The analysis of Two-way decks is performed in RAM Frame for the purpose of calculating the gravity loads on the frame members, and in RAM Concrete; it is not performed in RAM Steel. Hence, any loads on Two-way decks would not get distributed to steel framing.

Orientation

(One-Way slab action) Used to specify the direction that surface loads are distributed to the supporting members. It is also used in RAM Steel Beam for composite beam design and in the compression flange bracing criteria.

- span the global Y direction
- span the global X direction
- span the at the specified Angle (between 0 and 180 degrees), measured counter-clockwise from the global X direction (horizontal on the screen)
Parallel To - click Pick to associate a member or wall parallel to the deck span
Perpendicular To - click Pick to associate a member or wall perpendicular to the deck span

Drop Cap

(Two-Way slab action) Drop Caps are areas decking around columns that have different properties. (Typically, they are thicker than the surrounding decking.) Each Drop Cap is attached to the top of a specific column. If that column moves, the drop cap moves with it. If the column is deleted, the drop cap is deleted as well. Multiple drop caps may be assigned to a single column. If this is done, they behave just like regular decking, in that the last one added is takes precedence over any drop caps underneath it.

Drop Caps behave exactly the same as regular decking, with the following exceptions:

They are attached to a column and consequently move with that column and are deleted when that column is deleted.
They are kept above all regular decking, so adding regular (non drop cap) decking to the same area after the drop cap was created results in the regular decking being "underneath" the drop cap, meaning that the drop cap takes precedence in the area of overlap.
The deck show command shows the drop cap properties for drop caps.
The deck change command does not allow the drop cap setting to be changed.

While drop caps are always initially square or rectangular, the Change Polygon command can be used to make them any desired shape once they have been initially created as a square or rectangle.

Framing System

Select the framing system used:

Composite - includes concrete on metal deck, precast plank, and flat slabs. Concrete properties and shear stud information must be specified. This information is used by the RAM Steel Beam module to calculate the composite section properties of composite beams. Refer to the RAM Steel Beam manual for more information.
Noncomposite - includes all other systems, such as grating, checkerplate, and roof deck
Concrete - used in conjunction with flat slab, flat plate, and concrete beam and column structures

decking / slabs table

Lists the decks and slabs that correspond to the current material section

Graphics Mode

Provides multiple tools for adding, editing, deleting, or reviewing deck and slab assignments in the current layout.

Setting	Description
Whole Floor	assigns the deck to the entire floor. It does this by creating new points 5 ft. (1.52 m) beyond the floor dimensions in each direction, and laying down a rectangular polygon. This ensures that the whole floor and slab edges are covered with a deck polygon. If the floor has more than one diaphragm, the Whole Floor command will assign the deck to all diaphragms on that floor.	Tip: Generally the best way to model the deck assignments is to first lay the most commonly used deck over the whole floor, using the Whole Floor command and then overlay the areas where other decks or deck orientation occur by using the Add command. Exception: this may not be true for layout types with sloping framing.
Whole Diaphragm	the target cursor appears with which to select the diaphragm to which the currently selected deck properties are to be assigned. Note a difference between the Whole Floor and Whole Diaphragm commands: whereas the Whole Floor command creates a simple rectangular polygon slightly larger than the layout, the Whole Diaphragm creates a polygon precisely the same as the slab edge outline. The Whole Diaphragm command can be used on a floor type with just one diaphragm. Note: If the framing on a floor type is expanded, the deck polygons originally laid down using the Whole Floor or Whole Diaphragm may no longer encompass all of the framing, and the commands may have to be repeated (or the polygon modified as explained below).
Add	Click to draw a deck polygon. For One-way decks, except at perimeter beams with slab edges as described above, polygon sides laid down with the Add option must lie exactly on beams. They should not cut randomly through a bay. Two-way deck polygon sides do not need to be laid down on beams, but can by laid out anywhere within the slab edge.
Add Drop Cap - Fence
Change
Change Polygon	When using this command, first click on the polygon to be modified, which will cause the edges and vertices of that polygon to be highlighted. The following can then be performed: To move a vertex, click on the vertex to be moved and then click on the new location. To add a new vertex, move the cursor to the middle of the side on which a new vertex is desired; a new vertex will appear. Click on it to create it. Then click on it again and move it to the desired location. To combine two adjacent vertices (thereby eliminating one side of the polygon), click on the vertex to be eliminated and move it to vertex to which it is to be combined.
Change Priority	when multiple deck polygons are laid down in the same area, the polygon on top (the last one laid down) takes precedence over any polygons (or portion) below. In some cases it may be necessary to change the order, or Priority, of these polygons, moving them up or down. This can be done using the Change Priority command. When invoked it displays a list of all of the deck polygons on that layout type. Selecting a polygon from that list causes the polygon to be highlighted in plan. The Up and Down arrows can be used to move that polygon up or down in priority. This command is useful, for example, if a polygon is completely covered by other polygons and is no longer necessary; it can be moved up the list and then deleted.
Delete - Single	Click and then select the deck to be deleted.
Delete - Fence	Click and the fence an area. All of the decks within the fenced area will be deleted.
Show	Used to display the properties of deck assignments for a selected deck. To see a list of the polygon vertices, select the More>> button. Tip: Deck assignments are depicted on the screen by a hatching pattern while in Deck Assign mode. They can also be displayed by toggling the Show Decks option of the Options > Set Show Options command; there is an option to either show the decks clipped to the slab edge or unclipped to the slab edge.
Show Same	Opens the Show Same Decks dialog, which lists all of the decks. When one is selected from the list, all occurrences of that deck type are highlighted in the plan. This provides a quick way of verifying that the correct decks have been assigned in each location. Tip: This provides a quick way of verifying that the correct decks have been assigned in each location.

Property Table

Opens the Deck/Slab Property Information dialog, which is used to enter the Composite, NonComposite, or Concrete Floor System Property Information for all decking/slabs to be used in the current model.