tie-plate

from The Century Dictionary.

• noun A casting placed under the nut of a bolt or tie-rod to distribute the pressure and protect the wood.
• noun In railroad construction, a broad fiat steel or iron plate, sometimes corrugated, placed on a tie and under the base of a rail to distribute the load and prevent the rail from cutting into the face of the tie.
• noun In iron ship-building, a narrow longitudinal or diagonal plate on top of the beams of a deck not having a complete metal deck.
• noun A main carline.