U-bolt

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A bolt shaped like the letter U, fitted with threads and a nut at each end.

from The Century Dictionary.

• noun A bar of iron bent into the form of the letter U, fitted with a screw and nut at each end. It is used in car-building to form carriers and supports for brake-rods, chains, and other connections.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A metal fixing in the shape of the letter U, which has a pin or screw bolt closure which fits across the two ends making a closed clamp