Abnormal deflections in construction stages

Answer:

The singular error occurred in the first stage because the deck element was not activated and then the beam girder could not resist rotation in the x axis.
In the case of the bearing, the rotation occurs in the z-axis because it resists dy only at the mid-node of the five nodes which is defined as elastic link.

Therefore, for the stage before the Deck element is activated, a temporary boundary must be set to resist Rz and Dy on the leftmost beam element.

01. Set a new boundary group (Temp.)

02. Define a boundary that resists Rz and Dy at the left end of the beam element.

03. Activate the corresponding boundary group (temp.) At the first construction stage.

04. In the third construction phase where the deck is activated, the thawing boundary group.