Loads Terms
| Setting | Description |
|---|---|
| Precast - DL, Precast - ADL (LFD Design Code Only) |
Loads acting on the precast section are specified for individual beams either as line loads or point loads (for location of point loads, input location from centerline of left bearing). These loads act on the bearing-to-bearing length. The moments and shears resulting from these loads are not distributed to other beams in the same span. |
| Precast - DC, Precast - DW (LRFD Design Code Only) | The dead load of components (DC) and dead load of wearing surface (DW) loads acting on the precast section are specified for individual beams either as line loads or point loads (for location of point loads, input location from centerline of left bearing). These loads act on the bearing-to-bearing length and the moments and shears resulting from these loads are not distributed to other beams in the same span. |
| Composite - DL, Composite - ADL (LFD Design Code Only) | Loads acting on the composite section are specified for the entire span length either as line, area (input width over which these loads will act), or point loads (for location of point loads, input distance from centerline of left pier). These loads act on the bearing-to-bearing length for simple spans and between the pier center lines for multi-span structures. The moments and shears due to these loads are distributed to all other beams in the same span based on the dead load distribution factor. |
| Composite - DC, Composite - DW (LRFD Design Code Only) | The dead load of components (DC) and dead load of wearing surface (DW) loads acting on the composite section are specified for the entire span length either as line, area (input width over which these loads will act), or point loads (for location of point loads, input distance from centerline of left pier). These loads act on the bearing-to-bearing length for simple spans and between the pier center lines for multi-span structures. The moments and shears due to these loads are distributed to all other beams in the same span based on the dead load distribution factor. |
| Live Loads (LRFD Design Code Only) |
WithPrecast/Prestressed Girder, you can specify which live loads you want included in the Live Loads section of the Loads tab screen. A list of the default live loads will appear in the list under Available, which include Design Truck, Design Lane, Design the list under Available and click the >> button. The selected load will appear in the list under Selected. For any span configuration, the Design Truck, Design Lane, and Design Tandem are automatically selected by default and cannot be excluded by the user. To include Tandem, Double Truck, and Double Tandem. To select a live load, highlight the load in either the Double Truck or Double Tandem, highlight the appropriate item in the list under selected. Double-click on the not-incl. item to activate the Select Live Load screen and select a truck ID. You can remove or de-select either the double truck and/or double tandem by clicking the << button. To select a permit vehicle (PV), highlight the load in the list under available and click the >> button. Once a permit vehicle is selected click the << button to remove or de-select it. |
| Select Live Load Screen |
You can select a different load in each category by double-clicking on the load in the list under Selected. This will activate the Select Live Load screen as shown in fatigue 1. Highlight the load in the list displayed on the screen and click Select. To view the details of a specific load, highlight the load and click View for the Edit screen to activate showing the details of the selected load, as shown in figure 2. Note: You cannot modify any of the information displayed on the screen. All the items listed on the Select Live Load screen are the items existing in the default library. To modify any of these loads, you must select the Live Load option from the Libraries menu. You also have the option of including the effect of LL deflection and/or pedestrian loads in the analysis by selecting the appropriate check boxes under the Live section on the Loads screen.
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| Live Loads (LFD Design Code Only) |
As with the LRFD design code, a list of the default live loads specific to the Standard (LFD) design code appears in the list under Available in the Live section of the Loads tab screen. However, no loads are "preselected" and included in the selected box. Notice that the names of the live loads are different from LRFD. To select a load, highlight the load in the list under Available and click the >> button. Since Precast/Prestressed Girder now stores lane loads (L) and truck loads (T) separately, you must select both the truck load and corresponding lane load in order to correctly simulate the AASHTO (LFD) specified live loads. Note: The Live Loads in this group are only for design. Please refer to Rating Parametersfor details on selecting Live Loads for Rating Analysis. If you are using Precast/Prestressed Girder purely for rating, not design, you can leave the selected list box under Design Live Loads Grid for all spans in the bridge
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| Pedestrian Loads (LRFD and LFD Design Codes) |
Select the Include Pedestrian Load check box and input the magnitude of the adjustable uniform distributed load in the field. The uniform distributed load is placed on the portion of the span between consecutive tenth points. A static analysis is performed with only that portion of the span loaded. If the moment and/or shear at the segment due to the load on the portion loaded are positive then it is added to the positive moment and/or shear envelope. If it is negative, it is added to the negative moment and/or shear envelope. At the same time, corresponding moments and shears are also computed and updated where appropriate, and then the next portion of the span between tenth points is loaded and results are updated again. |
| Optional Live Load Deflection (LRFD Design Code Only) |
According to the LRFD design code, if the user invokes the optional live load deflection criteria specified in LRFD Art. 2.5.2.6.2, the deflection should be taken as the larger of (a) the resulting deflection from the design truck alone, or (b) the resulting deflection from 25% of the design truck taken together with the design lane load. If you select the Include LL Deflection option, the above two conditions are checked and the deflection under the governing load is printed in the camber and deflections section of the printout. |
| Temperature Loads |
Precast/Prestressed Girder allows the input of temperature loads, either uniform, gradient or multi-linear temperature load as per LRFD specifications 3.12.2, 3.12.3. If the temperature load is input, the program calculates and reports the related stresses and displacements (along X). On the Analysis Parameters Load Factors tab, the load factors for the temperature loads can be specified for the various default limit states considered in Precast/Prestressed Girder. |
