Evaluation and modification of joists is often required due to the addition of roof top units, underhung conveyors, loading increases, field deviations, or other changes not contemplated in the original specification for the joists or joist girders. The purpose of this digest is to present procedures, and to suggest details for the modification or strengthening of open web steel joists and joist girders. Both open web steel joists and joist girders will be referred to as joists in this digest.