This command is used to access Beam entries in the library file currently loaded. To view the contents of this library, select Beam Sections from the Libraries menu or from its respective icon. The sections listed upon opening this screen correspond to the currently loaded section library file (*.pr1) selected under Libraries | Setup. To load a different library file, you must use the Libraries | Setup menu.
FIGURE GO-70. Libraries | Beam Sections
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Libraries Menu
Note that a list of predefined section types appear on the left of the Beam Sections Library. These sections are standard sections, and although you cannot add a new type, you can add to or modify an item in the list. The beam types are used by the program to automatically identify various specific design and code criteria.
To add or modify an item, highlight the section type from the list on the Beam Sections Library and click the Add button. When the appropriate Section Detail dialog box appears, fill in the data for ID, Description, and dimensions. Note that each item ID must be unique (i.e., you cannot have two double-T beams with an ID of 12DT24).
FIGURE GO-71. Section Detail Dialog Box (Double Tee)
Notice the three options under Section Properties: User Input, Dimensions, and Drawing.
You can enter your own values for center of gravity, area, moment of inertia and vol/
area by selecting the User Input option. For hollow cores, this option also allows users to specify the top and bottom flange thickness and web thickness to be used in design calculations. If you select the Dimensions option, the program calculates the section properties based on the section dimensions entered above. (Note that the fields under Section Properties will be unavailable.) The third option, Drawing, allows you to draw your own beam section, as explained in the following section. In this case, the program computes the section properties based on the drawing. Note that, in any case, the user must enter some dimensions, regardless of the option selected for computing section properties. These dimensions are used for various engineering calculations by the program. To better understand this feature, we recommend experimenting using all three options offered. You will quickly observe the differences between each option.
The Volume/Surface Area ratio is used in the computation of losses and is computed as the ratio of the cross sectional area of the member divided by the perimeter of the beam.
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Drawing the Beam Section
Click the Edit button on the Section Detail dialog box to open the Section Drawing screen, as shown below. Use the control buttons on the left of the screen to define your own beam section. If you move the mouse over these control buttons, a description of the button displays in the status bar at the bottom of the screen.
FIGURE GO-72. Section Drawing Screen
The control buttons on the left side of the Section Drawing screen are explained below.
Return and Update. This button accepts the section drawing and returns to the Section Detail dialog box.
Drawing Properties Settings. This button allows you to edit the drawing limits, grid and snap settings. This button opens the Drawing Properties dialog box. Enter the desired information and click the OK button.
Add New Polygon. This button starts the mode to draw polygons composed of straight lines. Click the left mouse button to add sides; a node will appear. Right-click on the last node to close the drawing.
Add New Circle. This button allows you to add a circle to your drawing. First, click the location where you want the center of the circle. Move the mouse until the desired circular radius is reached and click again. The Circular Section dialog box displays;
modify the values if desired and click the OK button. The circle will be added to the drawing. If a circle is drawn completely inside another polygon, then it is treated as a cut-out (or hollow).
Add Nodes. This button allows you to add nodes to the polygon. When you click this button, all the nodes that comprise the polygon and circles become visible. To add
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Libraries Menu
additional nodes, click anywhere on any polygon edge (between two nodes). Note that to add a new point between two existing points, both existing points must be visible on the screen. You can zoom in, zoom out, or expand the size of the drawing editor window. To add a node between existing nodes, make sure you can see both nodes on the screen.
Delete Nodes. This button allows you to delete a node on the polygon or entire circle.
Selecting this button displays all the composing nodes. Click any node on the polygon to delete that node. Click any node on the circle to delete the entire circle.
Modify Nodes. Click this button to modify the shape of the polygon. Clicking this button displays all the composing nodes for the polygon. To move a node, drag any node to another location. Click on a node and move the mouse without releasing the mouse button. Move to desired location and release the left mouse button.
Show Vertex. Click this button to display a list of vertices in a tabular format. You can modify the X and Y coordinate values for any node if desired.
Fillet. Selecting this button displays all the nodes that compose the polygon and circles. If you click any node in the corner of the polygon, a dialog box displays that allows you to select if the fillet is Chamfer or Fillet. You can also edit the fillet dimensions in this dialog box. Click the OK button to accept any changes and return to the drawing.
Zoom-In. This button allows you to zoom in on a part of the drawing. After clicking this button, you must select the area to enlarge by holding down the left mouse button, and then dragging the pointer over the part to be enlarged. While dragging the mouse pointer, a selection will be defined. Release of the button completes the task, and the selected part of the image appears magnified.
Zoom-Out. This button allows you to zoom out. As with the zoom-in feature, select an area to zoom out of by holding down the left mouse button, and then dragging the pointer over the part to be reduced. Release of the button completes the task, and the selected part of the image appears reduced.
Pan. This button allows you to pan the image. After selecting this button, you can then place the pointer anywhere in the image, hold down the left mouse button, and then drag the pointer in order to pan the view.
First, click the Drawing Properties button to specify the type of grid, spacing, and color, drawing limits, and snap dimensions. This opens the Drawing Properties dialog box.
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FIGURE GO-73. Drawing Properties Dialog Box
For example, if the grid has 25 units in the X direction and 25 units in the Y direction, enter “25” in the X and Y fields under Grids. Select the Active check box. You can also specify the type of gridline and color you want. Next, if the overall size of the section is 500in × 600in, the drawing limits in the X direction are (-250, 250) and in the Y direction, (0,600). Therefore, enter “–250” in the Min X field and “250” in the Max X field and enter “0” in the Min Y field and “600” in the Max Y field. Under Snap, select a useful snap spacing. Generally this number is a small common denominator of the drawing dimensions. For this example, the snap spacing is 10in. Enter “10” in the X and Y field and select the Active check box. Click the OK button and return to the Drawing Properties dialog box. Notice that the grid with your grid selections will be displayed in the drawing area.
Now you can start to draw the section beam. Select the Add New Polygon button.
Move the cursor inside the drawing area and click the left mouse button to click the starting point. This will be the first node. Although any starting point can be selected, do not select a starting point that will force the drawing outside the drawing limits.
Move the mouse across to the next location and click again. This creates the first edge of the section (and also the second point). Next, move to the third point and click to create the second edge. Repeat this until all points and edges have been entered and the drawing is complete. Right-click on the last node to close the drawing; it will fill in the drawing with color. To show the nodes on the drawing, click the Add Nodes button.
Note that to be able to add a new point between two existing points, both existing points must be visible on the screen. You can zoom in or zoom out or expand the size of the drawing editor window.
You can insert a circle in your drawing by clicking the Add New Circle button. Move the cursor to where you want the center of the circle and click the left mouse button.
Move the mouse until the desired circular radius is reached and click the left mouse button again. The Circular Section dialog box displays. Modify the values if desired and click the OK button to return to the Section Drawing screen. The drawing will be changed to show the circle you just created.
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Libraries Menu
FIGURE GO-74. Circular Section Dialog Box
When you have completed your drawing, click the Return and Update button to return to the Section Detail dialog box.
Click the Template button to open the Template dialog box, as shown below. This screen shows all possible locations where strands may be placed. Enter the values for height and the maximum number of strands allowed at that height. The height of the strands is measured from the bottom at the end of the beam. Remember that you are not entering the strand pattern here, but only the possible locations where strands may be located, used by the program in the auto-strand generation module in the Strand Pattern dialog box. It might help to visualize this template as the end beam template used in the casting yard by the fabricator to place the prestressing tendons.
FIGURE GO-75. Template Dialog Box
The program can also generate the Strand template automatically, by clicking Auto Generate button in the Template dialog box to open the Template Auto Generation dialog box, as shown in the following figure.
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FIGURE GO-76. Template Auto Generation Dialog Box
NOTE: If the template data already displays on the Template dialog box, then clicking the Auto Generate button will lead to the appearance of a warning message,
“Existing template will be erased. Do you wish to continue?” Selecting Yes will result in the deletion of any existing template data and enable the user to enter a few key parameters in the Template Auto Generation dialog box. To prevent this message from appearing, click the Clear All button prior to the Auto Generate button.
In the Template Auto Generation dialog box, four parameters to be entered are: Distance from bottom to the first Row, Distance between Rows, Min. distance from the last Row to top, and Number of strands per Row. After entering the data for these four parameters, click the Generate button to perform the template generation. After the template automatically generates, the data can still be edited on the Template dialog box by using the Add, Delete, and Modify buttons.
Click the OK button to close the Template dialog box and return to the Section Detail dialog box.
When you are satisfied with the section data, click the OK button and return to the Beam Sections Library. Notice that the ID and Description for the section you created appears in the Items list. Click the Save button to save the newly created section in the currently loaded library (or you can also save it under a different name by selecting Save As). At this stage you will get a message informing you that the beam section has been saved to the library. To modify an existing item in the list, highlight it and click the Modify button to edit the values. To delete existing items, highlight the item in the list and click the Delete button.
Now that the section file has been saved, click the Close button to close the screen and end this procedure.