I have a 2d beam model (B21). First, I apply moment releases M1 to the beam using the *Release command. It works well. In a further step, I need to do a moving mass analysis on this bridge model, so assigning a point mass and a surface-to-surface interaction are features that I need to use. When I add either a point mass or a surface-to-surface interaction ( I tested these features individually), any analysis (eigenvalue, static etc.) is just aborted even before starting to run by an error message " Degree of freedom 3, 4, or 5 has been specified on the model. Beam elements in space should be used with the *release option." It seems that Abaqus somehow perceives or converts the model to a 3D problem when either surface interaction or a point mass is added to the 2D beam. Analysis Input File Processor is getting aborted even before completed because using the *release command in 2D beam apparently creates incompatibility when these two features (surface and mass) are used. Please help me solve this issue.  

Abaqus ​​​​​​​