Dead Loads Dialog Box
This dialog box allows you to specify intrinsic self weight and to define Point and Distributed (trapezoidal) loadings for project loads and combinations of both Dead Loads (DC) and Added Dead Loads (DW). To open this dialog box, select the Loads/Analysis tab, select the analysis/design case from the drop-down list, and then either double-click the name of a loading in the Dead Load/DC Group or Superimposed Dead Load/DW Group, or right-click one of these groups and select the Add Load command.
Adding a Load (Point or Distributed)
CIP RC/PT Girder supports the modeling, analysis and design of either the full cross section or an individual girder. If the Optional Girder Analysis check box is selected on the Project tab, then individual girder analysis, in addition to the full cross section, will be available. CIP RC/PT Girder further supports placing Dead Loads and Superimposed Dead Loads directly on an individual girder. Dead Loads and Superimposed Dead Loads placed on the full cross section are distributed to individual girders. Refer to the Technical Discussion below for a discussion of how loads and other structural elements are shared between the full cross section and individual girders.
- Select the girder from the drop-down list in the Girder field.
- In the grid, select the load you want to add to by clicking anywhere in its row. A blue arrow displays on the left side of the grid to mark the selection.
- Click the Add Load button. This adds a new load after the selected one.
- Enter the load values in the grid. A definition for each parameter is available below.
Copying a Load to all Girders
This command allows you to quickly apply a defined Point or Trapezoidal loading to all girders. Refer to the Technical Discussion below for a discussion of how loads and other structural elements are shared between the full cross section and individual girders.
Including Self-Weight
To include self-weight, click the box next to the Include Self-Weight option. This option is only available for the Dead Loads/DC Group and not the Superimposed Dead Load/DW group, and is only applicable to the full cross section.
Grid Definitions
| Setting | Description | ||||||
|---|---|---|---|---|---|---|---|
| Gir | The girder to which the load applies. | ||||||
| Load Type | Select the load type from the drop-down list; the two options are Point and Trapezoidal.
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| Setting | Description | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| Reference Type | CIP RC/PT Girder allows you to locate Point and Trapezoidal loads using one of four methods:
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| Ref Num | Select the number of the reference item consistent with the method of locating the load. This will either be a span number or a support number. This field will be disabled for the Bridge and Continuous location methods. | ||||||||||
| Dist Unit | Select either ft (or m) or percent (%) as the method to locate the load along the bridge or girder. The two distance fields, Dist-1 and Dist-2 must be consistent with the location method. | ||||||||||
| Val-1 | Specify the value of the Point load or the starting value of the distributed loading. | ||||||||||
| Dist-1 | Specify the distance along the bridge or girder for the Point Load or the starting location of the distributed loading. This value must be consistent with the location method. | ||||||||||
| Val-2 | Specify ending value of the distributed loading. | ||||||||||
| Dist-2 | Specify ending location of the distributed loading. This value must be consistent with the location method. | ||||||||||
| Description | Specify optional descriptive text for the loading. |
Technical Discussion
The Dead Loads dialog box is used to add Point and Trapezoidal loadings (Dead/DC or Superimposed/DW) to the project loads and to combinations. These loadings are defined within a "named group" for reference and logical grouping. The loadings may be directed vertically downward by entering the positive load values, or they may be directed upward by using negative load values. Any number of Point and Trapezoidal loadings can be added to a named group, for example, "Sidewalk Load," "Diaphragms," "Construction Load," etc. and any number of named load groups may be added to a combination or the project loads.
The defined loadings for the combination are placed on the generated model and the responses to the structure are available on a named group basis. For example, if you defined four point loads to model the affects of diaphragms and put them into a single named load group called "Diaphragm," then you could get the response to the four point loads as a group, not individually. To see the response of the structure to each individual point load, put each point load into a separate named load group.
Keep in mind that loadings and combinations are added to a specific analysis/design case, i.e., Initial and Final and. Loads defined in this dialog box as part of a load combination (or limit state) all pertinent specification checks and design activities applicable to the combination's type will be affected by the loadings.
If you selected one of the time-dependent material models, such as ACI, CEB-FIP or LRFD, then loadings placed in the Initial analysis/deign case will experience creep affects. Loadings applied in the Initial and Final will not experience creep affects and creep is not part of the solution when Lump Sum Losses is selected. Creep affects for a named group loading placed in the Initial can be seen by comparing responses in the Initial and Final analysis/design cases.
Dead and Superimposed Dead Loads defined on the Full Section are automatically distributed to each girder in proportion to the width of the girder / total width of the bridge. Dead and Superimposed Dead Loads defined on an individual girders are automatically added to the Full Section.