Define Load Group

Function

• Define (create, modify & delete) load group names to which loaded nodes and elements are later assigned.
• In a relatively complicated model for a complex structure, grouping specifically loaded nodes and elements becomes handy when the groups of the loads are to be repeatedly selected. Using the load group names, can we then select (Select Identity) or activate (Active Identity) frequently used load groups. Load groups are especially dedicated to Construction Stage analysis (of a sequential bridge construction) where each part of the total structure erected in each stage may be subjected to different loadings.
• Load groups can be defined in Define Load Group first. Next, the desired nodes and elements loaded with particular loadings can be selected in the Group tab of the Tree Menu and assigned to the groups by Drag & Drop. Or, the load group names can be directly assigned at the time of defining the loads.

Call

From the main menu, select [Project] tab > [Group] group > [Group] > [Load Group]

Input

Fig. Define Load Group dialog box

Name

Enter the name of a load group to be created, modified or delete.

When a PSC box bridge is modeled by the use of Bridge Wizard of midas Civil, the names of the auto-generated Load Groups are as follows :

• ILM Bridge Model Wizard
  Self Weight: Self weight of elements (activated at Construction Stage CS1 and applied at the time of generating the elements)
  TB-Prestressn: Prestressing force of the primary tendons (T/B) at Construction Stage CSn
  Web-Prestress: Prestressing force of the secondary (web) tendons (activated at the stage immediately prior to the final stage)
  
  
• FCM Bridge Wizard
  Self Weight: Self-weight of elements (activated at Construction Stage CS1 and applied at the time of generating the elements)
  PSm-n: Prestressing force after constructing the n th segment of the m th pier from the left (activated at Construction Stage CSn+1)
  KeyPSm: Prestressing force in the bottom tendons after constructing the m th Key Seg. from the left
  FTn: Self-weight of the form traveler used to construct the n th segment (activated at Construction Stage CSn and deactivated at the next stage)
  FTn-m: Self-weight of the form traveler, FTn distinguished by the numbering m, which is numbered from the left. See Note below.
  KeyFTm: Self-weight of the form traveler used to construct the m th Key Seg. from the left (activated at the next stage of the final segment construction and deactivated at the subsequent stages one by one)
  WCn: Wet Concrete weight of the n th segment (activated at Construction Stage CSn and deactivated at CSn+1)
  KeyWCm: Wet Concrete weight of the m th Key Seg. from the left
  Time Loadm: Additional aging of concrete girder cantilevers supported on a pier relative to the next concrete girder cantilevers supported on the adjacent pier at the time of constructing the joining Key Seg.
  In a typical FCM construction, a pier, its pier table, and the cantilevers on each side of the pier table forms an assembly. Each assembly is constructed at different timing, and these assemblies are joined by the Key Segs. again at different timing. The form travelers at each assembly is removed at different timing, and their locations are identified as m th location from the left as in FTn-m.
  
  
• MSS/FSM Bridge Wizard
  Self Weight: Self weight of elements (activated at Construction Stage CS1 and applied at the time of generating the elements)
  WCn: Wet Concrete weight and the self weight of MSS Girders of the n th construction stage (activated at Construction Stage CSn)
  PSna: Prestressing force in external tendons (stressed in Cycles)
  PSnb: Prestressing force in internal tendons (stressed in Cycles)
  
  

Suffix

The Suffix entry field is provided for the convenience of creating a number of related group names simultaneously. This is mainly used to generate changing loading conditions pertaining to multiple construction stages.

The construction stages defined by using Construction Stage Wizard for Building automatically create the Load Groups of "#CS Construction Stage No."for the self-weight of the slabs and "#AD Additional Load No.- Construction Stage No."for additional loads.

Group Sorting

, : Sort in ascending/descending alphanumeric order

, : The selected group moves up/down one position in the list. The use of [Ctrl] or [Shift] keys permits multi-selection.

Add

The entered load group is created. The load groups as many as defined in the Suffix entry field are simultaneously created.

Modify

The designated load group name is modified.

Delete

Selected load group names are deleted. The use of [Ctrl] key permits multi-selection.

Delete Inv

All the load groups on the list are deleted except for the selected groups. The use of [Ctrl] key permits multi-selection.

Close

Close the Define Load Group Dialog Box.

Fig. Group tab

Use the Group tab of the Tree Menu to assign nodes and elements loaded with particular loading conditions to the defined Load Groups. First, select the nodes and elements loaded with particular loading conditions to be assigned to a group using the Selection functions. Next, drag and drop the load group name to which the selected nodes and elements will be assigned from the Tree Menu to the Model Window.

Fig. Select Load Type dialog box

Select the load types that will be assigned to the load group in the Select Load Type dialog box. Upon clicking OK, the selected loadings will be assigned to the selected nodes and elements, which will in turn be assigned to the load group.

When a number of loading conditions are defined by different load groups and assigned to a node or an element in a given construction stage, the accumulated effect is considered in that construction stage.