Box-drawing dashes:

─

U+2500;

━

U+2501;

┄

U+2504;

┅

U+2505;

┈

U+2508;

┉

U+2509;

╌

U+254C;

╍

U+254D;

╴

U+2574;

╶

U+2576;

╸

U+2578;

╺

U+257A;

╼

U+257C;

╾

U+257E;

▁

U+2581;

▂

U+2582;

▔

U+2594.

Caveat: characters can differ in appearance vastly with different fonts. Using the semantically correct character might not always look the best.