Answer:
The preferred steel type for W-shapes is structural steel and the its preferred ASTM designation is ASTM A992.
Explanation:
The ASTM A992 is a structural steel and it's the most available for w-shapes; besides its availabilty, its ductility improvements makes it the preferred choice; other common designations for this shapes are ASTM A572 Grade 50,0r ASTM A36, but this designations aren't as available as ASTM A992, and it has to be confirmed prior to their specification.
