What is the STAAD.Pro version you have ( 20.07.xx.xx number that you can find from within Help > About STAAD.Pro ) ? With the size of model you mentioned, I am not sure why you are having the memory issues even after commenting out the design. If you do not carry out the design, I would think it should analyze for all 600 combinations. Are you getting the memory overflow type error messages when you do that ? Using a very high value for the MEMORY command can also be detrimental.
For the design part, you may break up the CHECK CODE commands into multiple CHECK CODE commands each with a list of approximately 200 members and that can help. Upgrading the RAM can help too but it is difficult to conclude what is causing the errors in memory without actually looking at the model. There is a secure upload option where your uploaded file can only be reviewed by Bentley colleagues …wondering if that is possible for you to do. Else we can also create a service request and communicate with you on a one-to-one basis but even then also, you have to send the file for troubleshooting.
For the design part, you may break up the CHECK CODE commands into multiple CHECK CODE commands each with a list of approximately 200 members and that can help. Upgrading the RAM can help too but it is difficult to conclude what is causing the errors in memory without actually looking at the model. There is a secure upload option where your uploaded file can only be reviewed by Bentley colleagues …wondering if that is possible for you to do. Else we can also create a service request and communicate with you on a one-to-one basis but even then also, you have to send the file for troubleshooting.