Geometry Tab
This is the second tab in the series
In the Geometry tab follow these steps:
-
Input the bridge layout information to include overall width,
beginning and ending skew angle, left/right curb widths, supplemental
thickness, deck thickness, and haunch dimensions.Precast/Prestressed Girder automatically fills in the
Haunch Width field with the minimum top flange
width of all beams used in the project if the
Auto Compute Haunch Width option is checked.
Check the option
Ignore Haunch for Composite Section Properties
if you would like to ignore the contribution of the haunch to section
properties computation, but only consider the self-weight due to additional
haunch concrete. A 2-D cross section view of the bridge is created once
sufficient information has been provided. You can right mouse click on this
graphic to change the view to either plan or elevation view. You can also zoom
in, zoom out, pan or switch to the full screen viewer.
With this information, Precast/Prestressed Girder will automatically calculate the number of lanes using the default lane width; however, you can manually modify this value.
-
Input the span data. Notice that this section appears differently
depending on the span type selected.
If, the span type is specified as a simple span and the Standard (LFD) design code is selected, input the span’s precast length, bearing to bearing length, and release span before specifying the beam type/location. If you selected the design code as LRFD, data entry is similar to the Standard (LFD) version, except you will also have to input the skew angle .
if you selected the bridge type as multi-span and selected the Standard (LFD) design code, the screen will resemble. Data entry is similar as the simple span, starting with the bridge layout, span data, and beam type/location. To input the span data, you will need to click Add/Edit Multi-Span. This activates the Multi-span.
On the other hand, if you selected the bridge type as multi-span and selected the Standard (LFD) design code, the screen will resemble Figure 3. Data entry is similar as the simple span, starting with the bridge layout, span data, and beam type/location. To input the span data, you will need to click Add/Edit Multi-Span. This activates the Multi-span screen. If you select the bridge type as Multi-Span (Mixed), the Unit Data table will show up under Geometry Tab. You may define unit types (either Continuous or Non-Continuous) for individual units. Click the button Add/Edit Multi-Span, Multi-Span window will pop up, where you may assign individual spans to the related units.
-
Input all data related to the beam types and their cross-sectional
placement under Beam Type/Location.
Within a given span, you cannot have different beam
types, but you are allowed to specify a different beam type for each span,
provided there is no conflict with the topping data.
For example, if you selected the LRFD design code, you may not be able to specify I-girders in one span and Double Tee beams in another, since the topping data must be the same for all spans in the bridge. Also, for the LRFD design code, depending on the beam type selected, you may or may not be able to input topping data or select the transverse post-tensioned option (e.g, you cannot have integral concrete box beams transversely post-tensioned in Span 1 and beams with a cast-in-place concrete topping in Span 2).
For a complete pictorial representation and classification of the different beam types, see LRFD Table 4.6.2.2.1-1.
To input the beam type and location, select a span from the Span list and a beam from the Beam Type list. Next, select a beam ID from the Beam ID list and input a value in the Dist. From Last Beam field. To add another beam, simply click in the Beam ID column in the next row in the table and pick the specific Beam ID you wish to add. You can also use the Add Row and Copy Row buttons to add more beams to the cross section. Notice Generate and Copy To All at the bottom of the screen. These two buttons are valuable timesaving features. Generate allows the program to automatically generate equally spaced beams for you. Click Generate to display the Generate Beams, as shown in Figure 4.
Input the values for quantity of beams and amount of overhang, where overhang is the distance from the centerline of the first beam to the edge of the bridge. Click OK to accept the values. Precast/Prestressed Girder will automatically generate equally spaced beams for you. They will appear in the list under Beam Type/Location.
Now, you may also click Copy To All to copy the beam’s configuration in the current span (i.e., number of beams, beam type, etc.) to all the remaining spans.
