washers

huangyhg

washers?
i am looking for a certain type of washer, but i do not know what it is called.  our building has i-beam columns and between the columns there is cross-bracing.  the cross bracing consists of tension only threaded rods.  the threaded rods go through a punched hole in the i beams web and are tightened on each end.  under the nut there is a special washer.  it is flat on one side and round on the other.  it is used to compensate for the angle between the threaded rod and the column.  i cannot find these washers, and i do not know what they are called.  can anyone help?
thanks
steelforbrains,
   the carr lane catalogue has spherical washers.  their website,
tapered washers or half moon washers.
bevelled washer