ASCE 7-16 4.9.3

[2021member]

Hi all, my first time posting.

In overhead crane runway design, I am hoping someone could help me understand why the vertical impact % is applied to the self-weight of the crane and hoist, when the weights are not changing.

 

[phamENG]

Because the impact force is related to the mass/weight of the member. You're not increasing the self weight, you're applying a live load that is a percentage of the self weight.

 

[FacEngrPE]

Get a copy of "Specification for Design and Construction of Mill Buildings (AISE Standard No. 13), Association of Iron and Steel Engineers, Pittsburgh, PA".
Unlike building steel which is mostly 20% live load. crane runway girders see 80% live load. This makes the design very different.
AISC publishes Design Guide 7: Industrial Buildings--Roofs to Anchor Rods which also discusses the design of heavy duty crane runways.