What is the component that transmits loads from the deck to the substructure and marks the boundary between the superstructure and substructure?

• A. Deck
• B. Girders
• C. Bearings
• D. Substructure

Answer: (C)

Transverse load transfer from the upper structure to the foundations happens at the bearing. Bearings sit between the ends of the girders (superstructure) and the substructure (piers, foundations) and are the actual interface that carries vertical loads downward while allowing rotation and limited horizontal movement. This makes the bearing the boundary between the upper structure and the lower structure, accommodating movements from temperature changes, loads, and settlements without transferring all those effects rigidly into the substructure.

The deck is the surface that distributes load to the girders, but it is not the interface with the substructure. Girders are the primary load-carrying members that transfer loads to the bearings, not the boundary itself. The substructure is the lower part (piers, foundations) that receives the load via the bearings.