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Change sections

Section properties may be changed for various structural objects throughout the course of staged construction. This enables both the simulation of structural changes which occur from stage to stage, and the modeling of multiple configurations within the same structure. When section properties are changed for a stressed object, the software automatically removes the object, replaces its response with equivalent forces, adds the new section, then reverses the equivalent forces. Forces then redistribute both within the new object and throughout the structure.

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1. If the composite section is modeled as a single frame object, only the supporting girder should be modeled initially. First, frame property modifiers should be created through Define > Named Property Sets > Frame Modifiers. Next, apply the Change Modifiers option within staged construction to account for the increased stiffness and weight of the composite section, as shown in Figure 1:
   
   
   

   Figure 1 - Change modifiers

   
   

2. The second option is to explicitly model the individual components of a composite section. For example, a frame object may model the girder, then a shell object may model the slab. To simulate the hardening of concrete within the deck, the deck slab could be initially modeled with negligible stiffness (1e-4) and its full weight, then in a later construction stage, stiffness could be increased to its full value through property modifiers.

Change supports

Frame releases and a dummy frame object may be assigned to change the support or restraint type within staged construction. This may be accomplished through the following process:

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Additional details are available in the CSI  Analysis Reference Manual (Frame Element > End Releases > Named Property Sets, page 116).

Change frame releases

Frame releases may be changed through the following process:

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