Can I analyze multiple STAAD.Pro models in a batch without actually launching the software ?

Yes you can. To do that create a batch file with one command line for each file you are trying to analyze in a batch. For example if you have three STAAD.Pro models EXAMP 01.std, EXAMP 02.std and EXAMP 03.std, create a batch file in the same folder with the following lines

"C:\SProV8i SS6\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 01.std" /s 

"C:\SProV8i SS6\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 02.std" /s 

"C:\SProV8i SS6\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 03.std" /s 

Run the batch file and the models will be analyzed and you will find all the result files within the same folder.

For STAAD.Pro Connect edition it will be as follows:

"C:\Program Files\Bentley\Engineering\STAAD.Pro CONNECT Edition\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 01.STD" /s
"C:\Program Files\Bentley\Engineering\STAAD.Pro CONNECT Edition\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 02.STD" /s
"C:\Program Files\Bentley\Engineering\STAAD.Pro CONNECT Edition\STAAD\SProStaad\SProStaad.exe" STAAD "EXAMP 03.STD" /s