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The staged-construction operationsapplications described in this article were written in context with [SAP2000|sap2000:home], thoughwhile they also apply to [CSiBridge|csibridge:home].
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h1. Change sections

Section properties may be changed for various structural objects throughout the course of [staged construction|kb:Staged construction]. This toenables simulateboth the simulation of structural changes which occur from stage to stage, and the tomodeling modelof 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.

Additional details are available in the {new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} [_Analysis Reference Manual_|doc:CSI Analysis Reference Manual] (Nonlinear Static Analysis > Staged Construction > Changing Section Properties, page 399).


h1. Change modifiers

To apply staged construction to [composite sections|kb:Composite behavior], property modifiers may be changed through either of two procedures. This may be a suitable application, for example, when a precast girder initially supports its own weight and the weight of wet concrete whichbefore willthe thenslab curecures toand becomebecomes a composite slabdeck system.

The two options for changing 
These procedures[property modifiers|kb:Property modifiers] are described as follows:

(1)# If the composite section is modeled isas a single [frame|kb:Frame] elementobject, model initially only the supporting girder and then use 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 operation to account for the increased stiffness and weight of the composite section, as shown in Figure 1:
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!Change_modifiers_operation.png|align=center,border=0!
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{center-text}Figure 1 - Change modifiers{center-text}
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# PleaseThe notesecond that you would needoption is to firstexplicitly createmodel framethe propertyindividual modifierscomponents viaof "Definea >composite Namedsection. PropertyFor Setsexample, >a Frameframe Modifiers" menu command.

(2) Explicitlyobject may model the individualgirder, componentsthen (such as the girder by frame elements anda [shell|kb:Shell] object may model the slab. by shell elements) ofTo simulate the [composite section|kb:Composite behavior]. To model hardening ofhardening of concrete within the deck concrete, the deck slab could be initially addedmodeled with negligible stiffness (1e-4) and its full weight and then the, then in a later construction stage, stiffness cancould be increased to its full stiffnessvalue viathrough property modifiers.


h1. Change supports

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As of SAP2000 V15.0.1 and CSiBridge V15.1.1 (September While2011), it is not possible to directly change the type of support or restraint type in the staged construction in SAP2000 V15.0.1 and CSiBridge V15.1.1 (these are the current versions as of 9/2011), this can be accomplished by using frame releases and a dummy frame elementcondition.
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Frame releases and a dummy frame object may be assigned to change the support or [restraint|kb:Constraint] type within [staged construction|kb:Staged construction]. This may be accomplished through the following process:

# Define short and stiff frame elementobjects to represent the bearing[bearings|kb:Bridge bearings].
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"Define > Named Property Sets > Frame Releases" menu command to define# Assign frame releases representingwhich represent the final bearing condition forof thethese frame element defined in step 1.
# Define "Change Releases" operation inobjects by selecting Define > Named Property Sets > Frame Releases.
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# Within the staged -construction [load case|kb:Load case], use the Change Releases operation to change the frame releases.
, as shown in Figure 2:
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!Change_releases.png|align=center,border=0!
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{center-text}Figure 2 - Change supportsreleases{center-text}

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Please note that the following applies (please see the {new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} [_Analysis Reference Manual_|doc:CSI Analysis Reference Manual] (Frame Element > End Releases > Named Property Sets, page 116) for details):

_"When when property modifiers are changed inwithin a staged -construction Loadload Casecase, they do not change the response of the structure up to that stage, butand only affect subsequent response. In other words, the effect is incremental."_
 This means that the approach previously described above will work well when supports are being changed by adding restraints, as it is adequate to use the incremental approach in this case. However, the above approachchange supports, but it will not capture the redistribution of internal forces when supports are being changed by removing restraints., Forin thiswhich case, it modelingwould changebe ofmore supportsappropriate byto addingadd and remove [links|kb:Link]. This is accomplished by first removing the link elements would be more appropriate.

When using links, the procedure to change supports would be to remove link element(s) simulating the old support condition and replace it by a link element(s) simulating the new support condition.
{info} objects which simulate the previous support condition, then by replacing with links which simulate the new supports.

Additional details are available in the {new-tab-link:http://www.csiberkeley.com/}CSI{new-tab-link} [_Analysis Reference Manual_|doc:CSI Analysis Reference Manual] (Frame Element > End Releases > Named Property Sets, page 116).


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*Related Incidents:*
* {incident:no=38146|comment=Changing supports in staged construction.}
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h1. Change frame releases

Frame releases may be changed through the following process which follows:

* Define [frame|kb:Frame] end releases through Define > Named Property Sets > Frame Releases.

* Apply the end releases by selecting Change Releases within the staged-construction [load case|kb:Load case].