we are installing Tekla Structural Designer 2018. Learning purpuse.
Hi! Unfortunately Tekla Campus program is only for Tekla Structures.
You might want to discuss the possibility of a trial of Tekla Structural Designer 2018 with your local area office or reseller. You can find the contact information here: https://www.tekla.com/contact/offices-and-resellers
Are you an educator? See options for institution licensing.