Form select query output - array

I want my select form to return query like this

http://myexamplesite.com/store/?brand=nike+adidas+woodland

but it returns

http://myexamplesite.com/store/?brand=nike&brand=adidas&brand=woodland

What kind of change I have to make for the form

I tried setting the select - name="brand[]" name="brand[0]" but it returns

brand%5B0%5D=adidas&brand%5B0%5D=nike