Which of the following is NOT a type of bridge abutment?

Answer: C — Pier abutment

A pier abutment is not recognized as a standard type of bridge abutment, making it the correct choice for this question. Bridge abutments are structural elements that support the ends of beams or girders and help transfer loads from the bridge deck to the foundation and surrounding soil. Closed abutments are designed to retain the earth behind them, providing lateral support that is crucial for stability. Stub abutments, on the other hand, are short structures that support only a portion of the bridge's superstructure without extending into the backfill. Integral end bents function as both an abutment and a support for the bridge's superstructure, creating a continuous connection that provides enhanced structural integrity. In contrast, a pier abutment is primarily used to support a bridge span over a body of water or valley, serving a different purpose than traditional abutments which are typically at the ends of the bridge. This distinction is key to understanding the functional roles of these structures within bridge engineering.