| Setting
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Description
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| Analysis Options
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Type
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In the Analysis Options group,
select the type of analytic model. Options are Grillage, Line Girder and FEM.
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Dynamic Load Allowance
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Enter the dynamic load
allowance for design and fatigue. Default values of 1.33 and 1.15 are used for
design and fatigue respectively.
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Include live load analysis
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Check this box to include
Live Load Analysis in the final Analysis results. Uncheck this box to generate
dead load results only. The default is checked .
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Design lane discretization
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This value is used to simulate
lane load as concentrated loads and to locate the axle load on the influence
surface. The default value is 9 inches. A larger value generally will decrease
processing time with potentially less accuracy.
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Truck step
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This is the incremental
distance that will be used to move the truck along the bridge during live load
analysis. The default is 24 inches. A larger value generally will decrease
processing time with potentially less accuracy.
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Deck splits per span
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This is the number of
transverse divisions made in each span for locating transverse deck elements in
the grillage model. The default value is 25. A larger the number of deck splits
will increase accuracy at the expense of memory demand.
If the green check box
 is visible next to the Run
Analysis button the current setting is sufficient for live load analysis.
If a yellow exclamation symbol
 is visible the memory demand
required for the current deck split setting is large and analysis may not be
possible. When this happens, decrease the number of deck splits by pressing the
down arrow until the symbol changes to a green check.
If a red "X" symbol
 is visible the memory demand
required for the current deck split setting is too large and analysis will not
be possible. When this happens, decrease the number of deck splits by pressing
the down arrow until the symbol changes to a green check. This parameter has no
effect on line girder analysis.
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Lane Setup
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Press the Lane Setup button
to activate the Lane Setup input options dialog. Lane setup applies to grillage
analysis only. Two options are available to control placement of lanes on the
bridge desk (1) Mirror and (2) Float.
| Setting | Description |
|---|
| Lane Layout
|
Select the lane layout to be used:
- Fixed -
see description above
- Mirrored
- see description above
- Float -
see description above
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| Lane Width
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Enter the desired lane width
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| Max. Lateral Step
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Enter the maximum lateral step (Float
option only). The maximum lateral step is the distance between each lane float
increment.
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| Actual lateral step
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This is the actual lateral step that is
computed by the system. The computed lateral step insures that the lanes will
float such that they will end aligned as shown above (i.e the inside if the
first lane will align with the edge of deck.
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| Lane Path
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For the Float option, select the left or
right edge of deck as the lane path reference (default is left).
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| Vehicle Path
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Select the vehicle path that will be used
in each lane:
- Center of
lane - the vehicle will be placed in the center of each lane only when
determining the maximum effect.
- Left,
center and right within lane - the vehicle will be placed successively in the
center, left and right of each lane when determining the maximum effect.
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| Apply
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After selecting the lane layout press the
Apply button to finalize the layout parameters and update the graphic display.
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| Roadway
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The roadway list contains all lane
positions that will be used in the live load analysis. To view any of the
roadway positions select it from the drop-down list.
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| OK
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Press OK to save the changes and exit the
dialog.
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| Cancel
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Press Cancel to exit the dialog without
saving changes.
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FEM Meshing Settings
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Enter desired Meshing Settings. Options are 'Deck Mesh Size'
and 'Girder Web Mesh Size'. This setting is only available for FEM analysis.
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Compute flange lateral bending
per NCHRP 725
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Check this box to activate calculation of flange
lateral bending based on NCHRP report 725. This option is only available for
Grillage analysis.
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Use equivalent torsion J
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Check this box to activate
calculation of equivalent J based on NCHRP report 725. Using this option will
result in improved torsional rigidity in the grillage model that is generated
by LEAP Bridge Steel. Selecting this option will have no effect when line
girder analysis is used.
This option is only available for Grillage analysis.
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Include haunch in section
property calculations
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Select this option to include
the haunch concrete in section property calculation. The haunch concrete is
that which lies between the top of the girder and bottom of the slab. The width
of the haunch concrete is assumed to be the width of the top flange of the
girder.
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Live Load Distr. Factors
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Available for Line Girder
analysis type and are applied to forces, moments and to deflections
calculations.
| Setting | Description |
|---|
| Edit Range
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This option permit to edit Live Load
Distribution Factors range one / multi-lane, fatigue for negative and positive
shear / moment.
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| Recalculate all factors
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Pressing this button is recalculating all
Live Load Distribution Factors for each location(Point of Interest).
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| Include rigid frame assumption
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This check box is adding rigid frame in
recalculation of Live Load Distribution Factors. Checking this box enables
rigid frame/cross section calculation for exterior beam distribution factors.
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| Left/Right Curb Width
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The non-editable values come from
Appurtenance locations and represent distance from bridge overhang to middle of
parapet.
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For the selected Stage, all load cases for that
stage will appear. Select the load case that result viewing is desired from the
list.
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| View Results
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Stage:
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Select the stage for result
review for the drop-down list .
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Show Load Cases
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Check this option to view
results for individual load cases. The load cases for the currently selected
stage will be available to display.
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Show load combinations
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Check this option to view
results for load combinations. The load combinations for the currently selected
stage will be available to display.
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Diagram Type
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Select the diagram type to be
displayed from the dropdown list. Options are:
- Shear: Fy
(vertical shear)
- Moment: My
(lateral moment in the main member)
- Moment:
Mz.(major axis bending moment in the main member)
- Displacement:
Dy (vertical displacement)
- Camber: select
to display camber diagrams and tables. When Camber is selected the load cases
list will show all dead load cases for all stages. Check the dead load case to
be included in the camber diagram.
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No. equal splits per span
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Select this option to show
results only at equal spaces along each span. By default the diagrams show
results at all points of interest. Select the number of splits per span using
the vertical arrows.
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All girders
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Check this box to view
diagrams for all members at once in 3D. Uncheck this box to see diagrams on a
member by member basis in 2D. When this box is unchecked the member to be
displayed is selected from the drop-down box below the check box.
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Text size
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Change the text size to
larger or smaller using the up/down arrows. If the text lead lines are too long
in a diagram decrease the text size.
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Camber tolerance
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Enter the camber tolerance to
be added at each POI n the camber diagram.
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Scale
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Use these slide bars to
change the vertical scale of the shear, moment and displacement diagrams.
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Show Reports
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Press this button to open the
Analysis report generator to generate printed reports for all analysis output.
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Save DGN
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Press this button to save the
currently displayed results to a MicroStation DGN file.
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| Run Analysis
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Press this button to initiate
analysis. See instructions for Deck splits per span above for the meaning of
the green check, yellow exclamation or red X. You can also hover over these
symbols to see their meaning.
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| Close
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Press this button to Close the
Analysis dialog.
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