What condition indicates that a load-resisting member is unfit for further loads?

Failure indicates that a load-resisting member is unfit for further loads because it signifies that the structural element can no longer perform its intended function of transferring loads. This can be due to various mechanisms such as ultimate failure or excessive deformation. When a member fails, it typically cannot support any additional loads and poses a safety risk.

Creep refers to the gradual deformation of a material under a constant load over time, which may reduce the performance of the member but does not necessarily render it unfit for further loads immediately. Fracture, while a specific type of failure, may not encompass all failure modes, such as buckling or yielding. Yield describes a point where a material has undergone plastic deformation but can still carry loads; it has not failed completely yet. Thus, failure is the most definitive condition that declares a load-resisting member incapable of sustaining further loads.