What is the purpose and typical locations of expansion joints in bridges?

• A. Expansion joints accommodate thermal expansion and contraction and relative movements; located at the ends of spans, at transitions between dissimilar structures, and at abutments where movement is expected.
• B. Expansion joints are only decorative and serve no structural function.
• C. Expansion joints are placed only in the middle of spans.
• D. Expansion joints prevent any movement at abutments.

Answer: (A)

Expansion joints are gaps designed to let the bridge deck move as temperatures change and as the connected parts shift relative to each other. They are placed where such movements are expected and need to be accommodated without causing damage or overstressing components: at the ends of spans where adjacent deck segments can move apart or together, at transitions between dissimilar structures where different parts may settle or expand differently, and at abutments where the deck meets the approach embankment and experiences settlement, rotation, or vertical movement. This arrangement keeps the deck continuous and watertight while allowing thermal expansion, contraction, and other relative movements to occur safely. They are not decorative, they are not limited to the middle of spans, and they do not lock movement at abutments.