Lateral Loads due to Occupancy of Metal Decks/Ramps

[EngDM]

Hey all,

I've read the document below for wood, but I am wondering if anyone has ever used it in steel deck/ramp applications (metal grating on channels). I'd imagine the steel would be much more rigid, so if I were to wager a guess at the loading, the most similar would be the table in the stiffest direction.

Another thing: we typically commercial design decks for 100psf live load as assembly areas, but the attached report only covers up to 40psf. I'm not sure if this is because the test was done in the US and you guys have different occupancy live loads, but would I have to extrapolate the tabulated values up to 100psf from 40? Seems like a MASSIVE lateral load if I do that.

 

[phamENG]

The only codified lateral live loads that I know of (in the US) are from grandstands and stadiums. They require a 12psf lateral live load, which is either 12% or 20% of the vertical live load depending on what the configuration and construction is. This is a 'swaying' load, so based on tests of synchronized movements of the crowd. It matches up pretty well with that report if I remember correctly, and so I use 12psf for exterior decks when providing an engineered design.

For an industrial walkway or platform where workers will be checking stores or maintaining equipment or traversing from place to place, I wouldn't expect much synchronized dancing, so a lower lateral force is likely justified. You could do the exercise of calculating the tractive force exerted by the foot of a 300lbf person accelerating from 0 to 3mph in the time it takes to take a step, and then extrapolate that to the expected density of dynamic live load occupancy.

 

[EZBuilding]

I initially thought of the grandstands and stadiums concept which phamENG identitified.

The only other thing to add would be ASCE 7-16 1.4.2 Lateral Forces which provides for minimum required lateral forces. In Florida, we have no seismic load considerations. I have used these provisions for interior equipment mezzanines which would otherwise not have a significant lateral load (outside of maybe the 5psf interior partition loads).

 

[phamENG]

Only problem with that is that it's meant for stability and uses only dead loads. You could apply it with live loads, but I'm not sure it would get you what you want. There's no rational basis to it.

I think 12% (or 1/8) for 'incidental' lateral live load and 25% for cases where you have either very flexible structures or a high probability of synchronized movements (or both) fits pretty well with the research.

 

[EngDM]

Only problem with that is that it's meant for stability and uses only dead loads. You could apply it with live loads, but I'm not sure it would get you what you want. There's no rational basis to it.

I think 12% (or 1/8) for 'incidental' lateral live load and 25% for cases where you have either very flexible structures or a high probability of synchronized movements (or both) fits pretty well with the research.

I'm curious of your thoughts on another case here. What would you do if you had say, a grocery store built on a triodetic foundation? The lateral load due to 12psf would for sure govern a simple raised CRU.

 

[phamENG]

Fascinating. Had to google that one. I'm not talking about huge stores - maintenance platforms, mezzanines, walkways, decks. An entire grocery store? Minimum seismic loading is likely to be sufficient for that.