Definition of "Concentrated Forces" in the Steel Manual 1

[EngTomPE]

I cannot find a definition of "Concentrated Force" in AISC. Does anyone know is AISC has defined a bearing length limit for a force to be considered concentrated. I wonder specifically with regard to web buckling. Checks for web local yielding, local crippling, and sidesway buckling all account for the length of bearing. Web bucking strength is independent of bearing length, so I'm wondering at what length is a force no longer considered concentrated? And, why isn't the bearing length considered for Web Compression Buckling?

 

[JoshPlumSE]

The AISC commentary says the following:
"Equation J10-8 is applicable to a pair of moment connections and to other pairs of compressive forces applied at both flanges of a member, for which Lb/d is approximately less than 1, where Lb is the length of bearing and d is the depth of the member. When Lb is not small the member we should be designed as a compression member in accordance with Chapter E. "