Forkligt Impact Loading

[eit09]

Has anyone ever come across any information on loads a forklift could create by running into the structure? I came across an Australian study that used a 1kip point load in the horizontal direction. This sounds reasonable just wanted to see what else is out there.

 

[youngstructural]

Don't know of anything specific against that, however there are some great photos on this forum from previous threads of just this kind of impact. Try to find "forklift versus structure" or something like that.

You can calculate the theoretical max from the same formulae used for impacts onto a barrier; Just involves the speed, mass (weight), and the deflection under the anticipated load.

Cheers,

YS

B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!

 

[JAE]

I think it would be more than 1 kip.

If you were to model a building column, say a 6 inch steel tube, and put a horizontal 1 kip load on it - the deflection would be a fraction of an inch.

I've seen columns hammered by forklifts before and they go beyond the elastic zone and are deformed by multiple inches.

 

[Ron]

I agree with JAE...would be quite a bit higher than 1kip. Look up the AASHTO procedure for bridge approach barriers. It gives the procedure to calculate what you're looking for.

 

[oneintheeye]

look up BS6779-01 if you have access to British standards, has design for bridge parapets under impact.

 

[ChipB]

WAAAAY higher than 1 kip.

Do the physics of F=ma and figure out how far the forklift would have to go before it stopped under a 1 kip force and I think you'll see it has gone all the way through the column.

I believe vehicular barriers are based on a 6k force, and they are designed to yeild so they sustain significant amount of damage and displacement under that loading.

 

[SteelPE]

This link has some of the pictures talked about above:

http://www.eng-tips.com/viewthread.cfm?qid=215858&page=3

These pictures should give you a warm fuzzy feeling about a 1 kip point load.

 

[dgkhan]

I am extremely sorry (especially eit09)to place a question here as it's so relevant. I read that some people are claiming that if Titanic would have gone straight and taken the impact Head on, it would have been less destructive to ship. I do not buy that though, any thoughts on this.

 

[drawoh]

dgkhan,

We have a forum672 forum. This would be a more appropriate place for your question.

The quick answer is that the Titanic was scraped lightly on the side to a length of around 300feet. This opened up six holds. The Titanic was designed to float with the first four holds flooded. A direct hit on the iceberg would have destroyed more metal structure and people would have spilled drinks, but the ship would have remained afloat.

Is the OP asking the correct question? I would want to know what the kinetic energy of a moving forklift was, not the force.

JHG

 

[eit09]

Thanks for all the posts. I am designing a platform that will be loaded peoriodically by forklifts. I have seen forklift drivers, some good but mostly they are free spirits. There is equipment next to the platform that is sensitive! I want to figuire out the deflection of my platform if a free spirit were to come along as to check if the equipment will be hit. I tried looking for information online (aashto "approach barriers", British code, etc) but no luck. Thanks again for some of the posts! Looks like I will just stick with good old Newtons law.

 

[weab]

This sounds like a classic energy situation. Determine a likely forklift speed and mass. Determine kinetic energy. 1/2*mv2

Then iterate deflection and determine how much load would be required to create that deflection. Determine potential energy. F*deflection.

When potential equals kinetic, the corresponding load for that deflection is your answer.

This answer will vary based on stiffness of impacted object. Stiffer/stronger objects will see larger loads, softer/flexible objects will see less load.

 

[youngstructural]

Sorry all, but have I missed something? What was wrong with the suggestions made by Ron, Herewegothen and myself? All of this work has already been done. There is no need to formulate your own solution, nor any need to work it out from fundamentals. Simply go get any decent performance based code for bridges and use the barrier design formulae.

There's no mystery here: If you want no plasticity, set your mu to 1 in the formulae, and implement the 95% of the maximum speed of the forklifts, with 95% of the maximum factored load. Then you simply work out the deflection for your column.

It will be huge, as it should be. And it will be fictitious unless you concrete fill, or encase, since it's going to rip under point loading.

Regards,

YS


B.Eng (Carleton), P.Eng (Ontario), MIPENZ (Structural-New Zealand)
Working in Canada, and missing my adoptive New Zealand family... at least I brought the little Kiwi with me!