How can I convert surface elements to plate elements
There is no direct way to convert surface elements to plate elements. Here is an indirect process of how do the same.
Save your STAAD model file by a different name.
Analyze the saved STAAD.Pro model.
Press “F12” key on the keyboard which is going to convert the surface to constituent nodes and plates.
You will NOT see the plates at first. Save the file. Close it and reopen it and you will see the plates.
However please note that there would be some amount of manual cleanup that would be required after the conversion. The converted model will generate some errors while opening as all information related to the surfaces are not completely deleted from the file upon conversion. You have to manually get rid of those. Also loads on surfaces would not be automatically converted to plate loads and has to be reapplied.