To simulate a two-span structure which is simply supported under dead load, and continuous under live load, a staged-construction load case is defined with five stages, outlined as follows:

• Stage 1: Add two frame objects, one for each span.

• Stage 2: Define frame end releases through Define > Named Property Sets > Frame Releases, then assign these moment releases to the start joint of the second span.
  
  Additional information is available in the Staged-construction tips and Staged-construction operations articles.

• Stage 3: Apply load to the structure. Response will be as though the system is simply supported.

• Stage 4: Fix the moment end releases which are applied in Stage 2.

• Stage 5: Apply additional load to the structure. Response will now be as though the system is continuous.

Structural response is presented in Figure 1:

Figure 1 - Structural response

Attachments

• SAP2000 V12.0.1 model (zipped SDB file)