button to the right of the drop-down lists to display the Frame Properties form or the Slab Properties form and add a new property definition to the model file.Use the Structural Geometry and Properties for Waffle Slab form to define a concrete waffle slab floor system with drop panels (solid column heads) and perimeter beams. Note that the connections between the ribs and either other ribs or the columns is modeled as fully moment resistant, as one would typically expect for a concrete structure.
Note: This form also displays when the Edit menu > Add to Model From Templates > 3D Structure command is used and the Waffle Slab button is clicked on the Add to Model - 3D Structure form.
Overhangs
Along X Direction -- Left Edge Distance and Right Edge Distance edit boxes. Use the defaults or specify positive values greater than or equal to zero for the distance from the perimeter grid line to the edge of the slab/deck in the X direction (i.e., left and right edges).
Along Y Direction -- Top Edge Distance and Bottom Edge Distance edit boxes. Use the defaults or specify positive values greater than or equal to zero for the distance from the perimeter grid line to the edge of the slab/deck in the Y direction (i.e., top and bottom edges).
Drop Panels and Ribs. Use this area to specify the inclusion of drop panels in the model. The program automatically specifies rib spacing for the initial slab property. Rib spacing can be modified using the Define menu > Section Properties > Slab Sections command.
Drop Panels check box. When this check box is checked, drop panels will be included in the model. If the check box is not checked, no drop panels will be included.
Size edit box. This edit box becomes available when the Drop Panels check box is checked. The drop panels are typically assumed to be square and centered on the columns, which are located at all grid line intersections. Use the default or specify a value for the length of one side of the drop panel. If the drop panel occurs at a perimeter column and the edge distance at that location is less than half of the drop panel size, the drop panel is truncated at the edge of the slab.
The actual size of a drop panel included in a model may be less than the value specified in this edit box. This happens because in waffle slabs ETABS does not consider the rectangular space between the centerlines of four adjacent ribs (joists) to be filled with a drop panel unless the drop panel size specified fully fills that space. The drop panel is ignored in any rectangular space between adjacent ribs that it does not fully fill.
Note that the thickness (depth) of the drop panel is controlled by the section property assigned to it in the Structural System Properties area of the form.
Restraints at Bottom options. Use these options to specify the type of restraint at the bottom of all columns.
None option. Specify no restraints (supports) at the bottom of all columns.
Pinned option. Specify pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free) at the bottom of all columns.
Fixed option. Specify fixed restraints (UX, UY, UZ, RX, RY and RZ restrained) at the bottom of all columns.
Structural System Properties drop-down lists. Use these drop-down lists to select frame section properties to be assigned to the columns and ribs and select slab section properties to be assigned to the slab and drop panels.
Column drop-down list. Select a frame section property for all columns in the template model.
Waffle Slab drop-down list. Select a frame section property for all waffle slab ribs (in both the X and Y directions) in the template model.
Drop drop-down list. Select a slab section property for all drop panels in the template model.
Click the button to the right of the drop-down lists to display the Frame Properties form or the Slab Properties form and add a new property definition to the model file.
Load drop-down lists and edit boxes. Use the drop-down lists and edit boxes in this area to specify dead and live loads on the model.
Dead Load Pattern drop-down list and Dead Load (Additional) edit box. When accessing this form to begin a model, the default Dead load pattern is the only option. Use the Dead Load (Additional) edit box to define uniformly distributed dead load in addition to the self weight of the structure. The self weight of the structure is determined by multiplying the weight per unit volume of each object that has structural properties times the volume of the object. The weight per unit volume is specified in the material properties.
Live Load Pattern drop-down list and Live Load edit box. When accessing this form to begin a model, the default Live load pattern is the only option. Use the Live Load edit box to define additional uniformly distributed live load.
TIP: If the Initialize from Existing .edb File option was selected on the Model Initialization form when the File menu > New Model command was used to begin the model, and if load patterns other than dead and live (e.g., snow, wind, wave) were created for the "existing .edb file" selected as the basis for creating the current model file, additional load patterns will be available in the Dead Load Pattern or Live Load Pattern drop-down lists.
Floor Diaphragm Rigidity check box. Choose rigid, semi-rigid, or no diaphragm. Both rigid and semi-rigid diaphragms also can be assigned to slab/deck members during the modeling process. The rigid and semi-rigid options affect only the analysis of the model. If the rigid option is selected, a fully rigid diaphragm is assumed. If the semi-rigid option is selected, the in-plane rigidity of the diaphragm comes from the stiffness of the slab/deck member that is part of the diaphragm.
Access the Structural Geometry and Properties for Wall Slab form as follows:
Click the File menu > New Model command to access the Model Initialization form and initialize a new model.
When the New Model Quick Templates form displays, specify the grid dimensions and story level, and the click the Wall Slab button.
Click the OK button.