In structural engineering and construction, an eyebar is a straight bar, usually of metal, with a hole ("eye") at each end for fixing to other components. Eyebars are used in structures such as bridges, in settings to which is applied only the force of tension, and not compression.
A closed eyebar will typically have a rectangular cross section of constant thickness throughout its length and a constant width for all but the ends. The ends will transition to a wider part that is terminated by a rounded end. In the center of this end will be a hole which will receive a cylindrical pin, which may have provision to accept one or more nuts or bolts. If of round cross section the bar will typically be end-forged to create a head, which is then flatted by additional forging. The head may then be machined to a precise thickness and flatness. An alternative method for using round bar is to form a loop and to forge-weld (hammer weld) or electrically weld the free end to the main bar.
Open eyebars are used in the cable anchorages of modern wire-cable suspension bridges. This allows the wires to be looped over the eye, rather than requiring threading through a closed eye.
The pins used to join bars will also be heat treated, usually to a degree of hardness exceeding that of the bars so that they will not shear under high stress.