Slab Openings

Icon	Description
	The Layout - Slab - Slab Openings command is used to layout Slab Openings in essentially the same way that slab edges are laid out. As with slab edges, slab openings are usually laid out along beam edges. However, they can also be laid out freeform to form arbitrary polygons, but care must be taken so that the polygons produce reasonable configurations, particularly if the decking laid down in the area is One-way.

Icon

Description

The Layout - Slab - Slab Openings command is used to layout Slab Openings in essentially the same way that slab edges are laid out. As with slab edges, slab openings are usually laid out along beam edges. However, they can also be laid out freeform to form arbitrary polygons, but care must be taken so that the polygons produce reasonable configurations, particularly if the decking laid down in the area is One-way.

The slab overhang is the distance from where the slab opening edge is laid out to the slab opening edge. For slab opening edges laid out along beams, this is the distance from beam centerline to slab opening edge.

While laying down the slab openings, a line defining the opening boundary will appear on the screen. It is imperative that the slab opening be a closed polygon and that it appears on the proper side of the beams. When using the Add command, the default setting requires that the slab opening be laid out in a counter - clockwise direction (Note that this is the reverse of slab edges, which by default must be laid down in a clockwise direction). If the slab overhang is set to 0, the slab opening can be modeled in either direction.

The In Bay Button may be used to place an opening in a bay. Once the In Bay Button is selected, the target cursor will appear. Clicking in a bay will produce an opening in that bay with the selected slab overhang. Clicking on a bay adjacent to a current opening will enlarge the opening to include the newly selected bay. Clicking inside a bay with an existing opening will replace the existing slab opening edge distance with the currently selected opening edge distance. The Slab Edge polygon must be laid out before using the Slab Opening In Bay command.

Tip: On layouts that are to be assigned Two-way decks, generally the most direct way to lay out slab openings is to create Grids and/or Construction Grids to generate the necessary SnapTo points, specify a Slab Overhang value of 0.0, and click from point to point until the slab opening polygon is complete. Note that this can also be done on layouts that are to be assigned One-way decks, but the In Bay command is usually more useful in that case.

In the analysis, no surface or snow loads are applied to the area inside a slab opening. Beams that bisect an opening are considered exposed beams; the deck does not support the top flange within that area and the beams are automatically designed as noncomposite in the RAM Steel Beam module.

Any number of slab openings may by assigned to a layout type.

To change the slab overhang of an existing opening edge, specify the new overhang value and use the Change command. Alternatively, merely lay down a new opening edge over the old with the Add command; it is not necessary to delete the old opening edge first.

To move an opening edge that was laid down in the wrong location or that needs to be moved to accommodate framing changes, use the Move command, select a opening edge segment, and move one end or the other to the desired new location. Alternatively, delete the segment and re-add it using the Add command.