Concentrated loads on steel plate

[RHB51]

I am designing an outrigger which will consist of steel beams at 30" oc with a 1/4" steel plate continuous over several spans. The concentrated load will be from a pallet jack with a very small wheel. My question is how much load distribution could I expect in the steel plate parallel to the steel beam supports. What would be a reasonable approach (not finite element).
Thanks

 

[271828]

I don't suppose you're into yield line analysis are you?

Other than FEA or YLA, your guess is about as good as anybody's as to an equivalent one-way span.

The thing I dislike soooo much about coming up with a width by judgment is that the strength can be made just about anything you want. Also, without having done a bunch of YLA or FEA, I don't know where the judgment comes from.

 

[jike]

This problem has been solved many times over in the pre-computer age after all wheel loads and steel plates have existed for a long, long time! No sense re-inventing the wheel or guessing at a solution.

I am not at my office right now so I do not have my references but will send info. as soon as I can.

 

[dbuzz]

Roarks Formulas should address this case, however I don't have my copy at hand.

In the Australian code for concrete design (AS 3600), the effective width of a one-way slab, deemed to resist moments caused by a concentrated load, not located near an unsupported edge, is given by the following equation:
b[sub]ef[/sub] = b + 2.4*a*[1-(a/L)]

where:
- b[sub]ef[/sub] is the effective width
- b is the load width
- a is the perpendicular distance from the nearer support to the section under consideration
- L is the clear span of the slab

If the load width, b, is conservatively assumed to be 0 and the concentrated load is at midspan, then the effective width of the slab, b[sub]ef[/sub], is 60% of the clear span, L.

 

[bkal]

Appendix A of British design code for steel bridges (BS5400-3) deals with this issue in quite a lot of details.

 

[DTGT2002]

One important consideration is your ability to limit the applied load to the outrigger to just pallet jacks or similar loadings. When rolling load to the outrigger, the assumption is probably fair. When someone puts a load onto the outrigger, things can get troublesome. However, this doesn't answer your question.

How much of the width do you need to work for the load to be acceptable? How will you attach the place to the beams?

Keep discussing. I have a plate loading reference somewhere if I can think of it, I will post.

Daniel Toon

 

[jike]

The references that I have are for designing battledeck floor plates and orthotropic steel deck bridges. All the formulas are in the form for AASTHO wheel loads with relatively large loaded areas (12" x 22" and 12" x 26"). It is not easy to modify these formulas for use with other loads and contact areas.

Roark does give a formula for stress on a rectangular plate (of different aspect ratios) for one concentrated load of a particular diameter.

If you have the possibility of two loaded wheels with the wheel spacing less than about 0.6 x clear span (as mentioned by dbuzz), you may need to take into account overlapping stresses by reducing the effective width to 0.3 x clear span + 1/2 wheel spacing. For wheels with small contact areas such as you have, I would ignore any affect that may have on increasing the effective width.

 

[RHB51]

Thank you for all of your responses.
Is there any chance you may provide Roark's formula?
I can't find it in any of my reference material.

Also, How can I find the British standard; I have done a search on google with no luck.

Thanks

 

[csd72]

Roarks Formulas for stress and strain is a book. No engineering company should be without one. You should convince your employer to buy a copy.

There is a table for this so it is not really possible to give you a formula.

csd

 

[dbuzz]

You'll find British Standards at

http://www.bsi-global.com/

 

[RHB51]

Thank you all for your time in responding to my question.
I will purchase the text as suggested and possibly the British standard also.

Thanks again to everyone.

 

[csd72]

Roarks will give you all the plate formulas you need, no need to buy the british standard if you have this.

csd

 

[bkal]

I would agree with csd72 as BS could be a bit too limiting for your needs.