Lateral Pedestrian Traction Loading 1

[phamENG]

I'm designing a maintenance platform - interior, no wind, seismic is negligible. I know there have been a few threads on this, but none seem to reach a rational conclusion and none seem to bring up an idea that I have, so I want to float it to see what others think.

Assume a 300# pedestrian (big guy carrying a big case of tools). If he's walking at 3.1mph (Wikipedia's average walking speed), or 4.55fps, is taking one step per second, and stops in one step, the force to stop him his:

F=ma
F=(300#/32.2ft/s2)*(4.55ft/s^2) = 42.4#, or about 14% of the applied gravity load.

This agrees pretty closely with the results found here, so I'm confident in the validity of my idea.

Now the question is how to apply it. In the linked article, they're looking at decks/balconies where a group of party-goers may do some sort of big, coordinated dance. This is an industrial application. No dancing, no synchronized marching, etc. Anyone have a suggestion for developing a rational application of this lateral load? If I design the platform for 100psf to account for personnel and material, a 14psf traction load on the whole surface feels like a bit much. Maybe a 60*0.14=8.4psf traction load based on a 60psf personnel loading for maintenance platform?

What do you guys think?

 

[jayrod12]

The 50plf linear load on guards would be my minimum load.

 

[SlideRuleEra]

...my goal is to better understand which situations don't fall in that category and need a more in depth look. I think that understanding is about all that stands between us and robots designing buildings for us.

I applaud your search for a rational lateral loading requirement for an interior industrial platform. I don't have an answer for you, but do have some recommendations on how to approach that subject. Electric generating stations in our system have plenty of platforms; I designed / constructed / modified / repaired a few, and was (technically) responsible for all of them.

These platforms have a hard life, design loads are little more than an educated guess. Plant operation is top priority and if that means a platform is used in ways it was not intended, so be it. For example, come-alongs may be attached to platform legs to skid heavy equipment parts across the floor... or chain-fall hanging from a platform used to lift heavy items... or heavy parts are stacked on a part of the platform, causing local overload (>100 PSF).

You mention that "there's pipe all around that inhibits full height bracing". I suggest the following:

1) Make a best efforts design, including bracing located where practical. (The piping is what plant operation is all about... it has priority over platform structure.)

2) Keep weight of individual structural members as low as practical. The platform will most likely have to be constructed (perhaps by hand) without disturbing the piping... possibly while the plant is in operation.

3) Don't skimp on permanent material to "save money". Most of the cost will be erection, not materials. You have expressed concern over both life safety and excess cost. There is another issue... depending on the platforms use, any problems (collapse, unstable, etc.) may impact plant operations. If that happens, a "gold plated" platform would "cheap".

4) Analyze your best efforts design to see what lateral load it can safely resist. A properly designed heavy-duty (100 psf) platform will probably surprise you with how robust and resilient it can be. For what it's worth, I would be looking for lateral load rating equal to, say, 20%+ of the live load rating. If the lateral load rating turned out to be higher than that, I sure would not do one thing to "lower" it.

http://www.SlideRuleEra.net

 

[Denial]

phamENG.[ ] I agree with the final comment in your 05Nov19@12:32 post.[ ] Such loads are highly relevant to the design of the handrail, its supports, and perhaps the part of the platform in the immediate vicinity of the load.[ ] But Newton's Third Law tells us that (apart from possible short term dynamic effects) they will usually be negated by some "equal and opposite" force somewhere else on the platform.

 

[phamENG]

SRE - thank you for a very informed and practical approach to the subject. I'll take a look at the "incidental" lateral capacity and see where I'm sitting. I'm sure you're quite right there.

Denial - my thoughts exactly, though I was afraid somebody would suggest a person running and jumping against it...(and the studying the dynamic interaction of counter vibrations from the jump and the impact is probably taking the analysis a tad too far)

jayrod - Industrial applications within certain occupancy restrictions are exempt from the 50plf rule - you only have to look at 200# point loads. That's how some industrial handrails can span 8 feet or more. They'll deflect like crazy, but they'll technically catch you. Though again, I point to my previous comment about application of handrail loads to the walking surface and Denial's contribution to that subject. I appreciate the input, though.