Backup with date to azure blob storage url

Im trying to do backups to an azure blob storage that have the date when the backup is made, that way the job does not fail when the backup is generated with the same name, I am concatenating *convert(varchar(500),GetDate(),112) + '.bak')* but im getting the next error in the job execution *Incorrect syntax near '+'. [SQLSTATE 42000] (Error 102). The step failed.* The script: Backup database model to url = 'https:containerurl/azurecontainer/model' + convert(varchar(500),GetDate(),112) + '.bak') go