Large models can be generated automatically using ETABS built-in templates. The models can then be modified with onscreen editing to satisfy specific situations.
While you are in the Building Plan Grid System and Story Defi-nition dialog box you can also add structural objects to your model from one of several built-in templates. It is not necessary that you add the structural objects from a template. You can al-ways draw, import, copy or replicate structural objects later.
However, in many cases it is simplest, most convenient and quickest to start your model with structural objects added from a template.
The Add Structural Objects from Template area of the Building Plan Grid System and Story Definition dialog box is reproduced below for reference.
Note:
You can create steel and con-crete building models using built-in ETABS templates.
These models can then be modified with onscreen edit-ing to satisfy specific situa-tions.
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Note that there is one steel building template called Steel Deck, five concrete building templates and a button for grids only where no structural objects are added to the model from a tem-plate. You can always tell which option (button) is currently se-lected in Add Structural Objects from Template area because its name is highlighted. When the dialog box is initially open the Grid Only selection is selected.
You can choose any of the templates by simply left clicking its associated button. When you choose one of the template buttons another dialog box appears where you can specify various types of data for the template. The data specified for each of the six templates (one steel and five concrete) are discussed in subsec-tions below.
When you are finished specifying data for a template you click the OK button to return to the Building Plan Grid System and Story Definition dialog box. You may notice that the button name for the template that you just specified is highlighted. If you then decide you defined the wrong type of template you can simply click another template button and define that data for it.
When ETABS creates the model it only adds structural objects based on the last button you clicked in the Add Structural Ob-jects from Template area, that is, the highlighted button. If the last button clicked was Grid Only then no structural objects are added to your model from template. You will simply start out with a grid system. You can then:
• Use the commands from the Draw menu to draw objects.
• Use the Edit menu > Add to Model from Template command to add objects to your model. See the section titled "Add to Model from Template" in Chapter 9.
• Import stories from a SAFE .f2k file. See the section ti-tled "Importing Files" later in this chapter.
• Import stories from another ETABS .edb file. See the section titled "Importing Files" later in this chapter.
• Copy objects (geometry only) from another ETABS .edb file. See the section titled "Cut, Copy, Paste and Delete"
in Chapter 9.
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• Copy objects (geometry only) from a spreadsheet. See the section titled "Cut, Copy, Paste and Delete" in Chapter 9.
• Use commands from the Edit menu to modify existing objects.
Note that when using the ETABS concrete building templates beams and slab ribs (joists) are normally modeled with depths equal to the dimension from the top of the slab (not bottom of slab) to the bottom of the beam or slab rib. Also note that in ETABS beams are modeled as line elements. Thus slabs with out-of-plane bending capability span from center of beam to center of beam in the ETABS model.
Steel Floor System Template
This template allows you to define a steel floor system. Follow-ing are discussions of each of the areas in this template:
• Slab Edge Distances: These are the distances from the perimeter grid line to the edge of the slab/deck. These distances must be greater than or equal to zero. They can not be negative.
• Secondary Beams: Checking the secondary beams check box means to include secondary (infill) beams. If the check box is not checked then no secondary beams are included. Secondary beams are the beams that do not frame into columns. The direction of the beams can be X or Y. Direction X means the span of the beams is paral-lel to the X-axis. Direction Y means the span of the beams is parallel to the Y-axis.
You can specify the number of secondary beams using one of two methods. You can either specify a maximum spacing in which case ETABS determines how many beams fit in the bay or you can specify a number of equally spaced beams.
Note that by default moment is released at the ends of all secondary steel beams, that is, they are pinned.
Tip:
By default sec-ondary steel beams are pinned.
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• Structural System Type: There are three possible op-tions for this item:
ü No Moment Frame: Moment is released at all beam to column connections, that is, these connections are pinned.
ü Perimeter Moment Frame: Moment is not released at beam to column connections for perimeter col-umns. Moment is released at beam to column con-nections for all interior columns. In other words, beam column connections at perimeter columns are moment resistant and at interior columns they are pinned.
ü Intersecting Moment Frame: Moment is not re-leased at any beam to column connections, that is, all beam to column connections are fully moment re-sisting.
• Restraints at Bottom: You can specify no restraints (supports) at the bottom of all columns, pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free), or fixed restraints (UX, UY, UZ, RX, RY and RZ re-strained).
• Structural System Properties: Here you specify frame section properties to be assigned to columns and beams and a deck section property for the deck/slab. The items in this area are:
ü Lateral Column: Column where the beam to col-umn connections are fully moment resisting.
ü Lateral Beam: Beam where the beam to column connections are fully moment resisting.
ü Gravity Column: Column where the beam to col-umn connections are pinned, that is, not fully mo-ment resisting.
ü Gravity Beam: Beam where the beam to column connections are pinned, that is, not fully moment re-sisting.
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ü Secondary Beam: All secondary beams.
ü Deck/Floor: The deck/slab.
• Load: The Dead Load Case drop down box lists all de-fined static loads that are type Dead. You can choose any one of these load cases in the drop down box (in most cases there will probably only be one) and then define additional uniformly distributed dead load for that case.
The word additional is used to indicate that it is in addi-tion to the self weight you specify using the self weight multiplier when you define the static load case.
The Live Load Case drop down box lists all defined static loads that are type Live. You can choose any one of these load cases in the drop down box and then define uniformly distributed live load for that case.
• Create Rigid Floor Diaphragm: Checking this box ap-plies a rigid diaphragm constraint to the area object rep-resenting the slab/deck.
Flat Slab Template
This template allows you to define a concrete flat slab floor tem with drop panels. No beams are included in this floor sys-tem. Following are discussions of each of the areas in this tem-plate:
• Slab Edge Distances: These are the distances from the perimeter grid line to the edge of the slab. These dis-tances must be greater than or equal to zero. They can not be negative.
• Drop Panels: Checking the drop panels check box means to include drop panels in the model. If the check box is not checked no drop panels are included.
The drop panels are typically assumed to be square and centered on the columns which are located at all grid line intersections. The Size item for drop panels is 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
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is less than half of the drop panel size then the drop panel is truncated at the edge of the slab.
Note that the thickness (depth) of the drop panel is con-trolled by the section property assigned to it in the Structural System Properties area of the dialog box.
• Restraints at Bottom: You can specify no restraints (supports) at the bottom of all columns, pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free), or fixed restraints (UX, UY, UZ, RX, RY and RZ re-strained).
• Structural System Properties: Here you specify a frame section property to be assigned to the columns and slab section properties to be assigned to the slab and drop panels. The items in this area are:
ü Column: All columns in the template model.
ü Slab: The floor slab not including drop panels.
ü Drop: All drop panels in the template model.
• Load: The Dead Load Case drop down box lists all de-fined static loads that are type Dead. You can choose any one of these load cases in the drop down box (in most cases there will probably only be one) and then define additional uniformly distributed dead load for that case.
The word additional is used to indicate that it is in addi-tion to the self weight you specify using the self weight multiplier when you define the static load case.
The Live Load Case drop down box lists all defined static loads that are type Live. You can choose any one of these load cases in the drop down box and then define uniformly distributed live load for that case.
• Create Rigid Floor Diaphragm: Checking this box ap-plies a rigid diaphragm constraint to the area object rep-resenting the slab and drop panels.
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Flat Slab with Perimeter Beams Template
This template allows you to define a concrete flat slab floor sys-tem with drop panels and perimeter beams. The only difference between this template and the Flat Slab template is that this one includes beams framing between the perimeter columns. Note that the connection between the beams and the columns is mod-eled as fully moment resistant, as one would typically expect for a concrete structure. Following are discussions of each of the ar-eas in this template:
• Slab Edge Distances: These are the distances from the perimeter grid line to the edge of the slab. These dis-tances must be greater than or equal to zero. They can not be negative.
• Drop Panels: Checking the drop panels check box means to include drop panels in the model. If the check box is not checked no drop panels are included.
The drop panels are typically assumed to be square and centered on the columns which are located at all grid line intersections. The Size item for drop panels is 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 then the drop panel is truncated at the edge of the slab.
Note that the thickness (depth) of the drop panel is con-trolled by the section property assigned to it in the Structural System Properties area of the dialog box.
• Restraints at Bottom: You can specify no restraints (supports) at the bottom of all columns, pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free), or fixed restraints (UX, UY, UZ, RX, RY and RZ re-strained).
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• Structural System Properties: Here you specify frame section properties to be assigned to the columns and pe-rimeter beams and you specify slab section properties to be assigned to the slab and drop panels. The items in this area are:
ü Column: All columns in the template model.
ü Beam: All perimeter beams in the template model.
ü Slab: The floor slab not including drop panels.
ü Drop: All drop panels in the template model.
• Load: The Dead Load Case drop down box lists all de-fined static loads that are type Dead. You can choose any one of these load cases in the drop down box (in most cases there will probably only be one) and then define additional uniformly distributed dead load for that case.
The word additional is used to indicate that it is in addi-tion to the self weight you specify using the self weight multiplier when you define the static load case.
The Live Load Case drop down box lists all defined static loads that are type Live. You can choose any one of these load cases in the drop down box and then define uniformly distributed live load for that case.
• Create Rigid Floor Diaphragm: Checking this box ap-plies a rigid diaphragm constraint to the area object rep-resenting the slab and drop panels.
Two-Way Slab Template
This template allows you to define a concrete flat slab floor sys-tem with beams interconnecting all of the columns. No drop panels are included in this template. Note that the connection between the beams and the columns is modeled as fully moment resistant, as one would typically expect for a concrete structure.
Following are discussions of each of the areas in this template:
• Slab Edge Distances: These are the distances from the perimeter grid line to the edge of the slab. These
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tances must be greater than or equal to zero. They can not be negative.
• Restraints at Bottom: You can specify no restraints (supports) at the bottom of all columns, pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free), or fixed restraints (UX, UY, UZ, RX, RY and RZ re-strained).
• Structural System Properties: Here you specify frame section properties to be assigned to the columns and beams and you specify slab section properties to be as-signed to the slab. The items in this area are:
ü Column: All columns in the template model.
ü Beam X: All beams in the template model that span in a direction parallel to the X-axis.
ü Beam Y: All beams in the template model that span in a direction parallel to the Y-axis.
ü Slab: The floor slab.
• Load: The Dead Load Case drop down box lists all de-fined static loads that are type Dead. You can choose any one of these load cases in the drop down box (in most cases there will probably only be one) and then define additional uniformly distributed dead load for that case.
The word additional is used to indicate that it is in addi-tion to the self weight you specify using the self weight multiplier when you define the static load case.
The Live Load Case drop down box lists all defined static loads that are type Live. You can choose any one of these load cases in the drop down box and then define uniformly distributed live load for that case.
• Create Rigid Floor Diaphragm: Checking this box ap-plies a rigid diaphragm constraint to the area object rep-resenting the slab and drop panels.
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Waffle Slab Template
This template allows you 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. Following are discussions of each of the areas in this template:
• Slab Edge Distances: These are the distances from the perimeter grid line to the edge of the slab. These dis-tances must be greater than or equal to zero. They can not be negative.
• Drop Panels and Ribs: Checking the drop panels check box means to include drop panels (solid heads) in the model. If the check box is not checked no drop panels are included.
The drop panels are typically assumed to be square and centered on the columns which are located at all grid line intersections. The Size item for drop panels is 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 then 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 that you input into the template. This hap-pens 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 con-trolled by the section property assigned to it in the Structural System Properties area of the dialog box.
Checking the ribs check box means to include waffle slab ribs in the model. If the check box is not checked no slab ribs are included.
Note: be filled with a drop panel un-less the drop panel size specified fully fills that space.
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Ribs are always provided interconnecting the columns.
The rib spacing specified is the typical center-of rib to center-of-rib spacing that applies to each bay of the structure. When the specified rib spacing is not an exact multiple of the bay width the ribs are still typically spaced at the specified rib spacing. Any required uneven spacing all occurs between the ribs on the grid lines in-terconnecting the columns and the first adjacent rib. This uneven space is always larger than the specified rib spacing. We assume that you will manually adjust the width of the ribs (beams) on the grid lines if necessary to maintain a constant form size for your waffle slab.
An example of this is shown in the next subsection for a one-way ribbed slab.
• Restraints at Bottom: You can specify no restraints (supports) at the bottom of all columns, pinned restraints (UX, UY and UZ restrained and RX, RY and RZ free), or fixed restraints (UX, UY, UZ, RX, RY and RZ re-strained).
• Structural System Properties: Here you specify frame
• Structural System Properties: Here you specify frame