I am building a 30' x 40' ,3 bay garage. I plan on using a 40' LVL beam in the center to support the upstairs attic. Can I install a large enough beam to make it free standing ? Or will I need support post?

That's an engineering question but with dead and live load above I would think you need at least 1 post. The company that makes the LVL should be able to tell you.