Concentrated Load over an area 1

[Acob]

Does anyone knows how the formulas for a single-span with concentrated load changes if this concentrated load is applied over a small area, for example 50x50 mm.

Thanks

 

[Focht3]

Frankly, not enough to be concerned with for most bridge or beam problems. That's only 1/4 of the area of the palm of my hand (~100mm by 100mm.) In my view, that's essentially a point load.

Why do you ask?



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[broekie]

I agree. That's a very small area. You bascially have a point load. Every point load is applied over some kind of area. There's no such thing as a "true" point load (at least not an example that I could think of).

 

[SlideRuleEra]

Concur completely with Focht3 & broekie and can add this: The assumed point load calculations will be (slightly) conservative; spreading a load over a small area, even the size you are considering will produce a fraction less moment in the span than the point load.

 

[tincan]

Unless the load is carried by a single beam, you should be able to distribute the load over a designated strip width depending upon the material and the design code. ie, the strip width carring a proportionate load is dependent upon the load and the span. That designated width should not change appreciable with the 50mm.

 

[Acob]

Thanks for the answers.

I agree with you, but in some standards of design of structures say that i have to consider a concentrated load applied hover a small area. I've seen catalogues of various products that have a table of loads and make this consideration and i can't understand the values that they presented.

 

[Focht3]

Could you give specific examples?



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[corus]

The reference probably relates to local stresses in the bending of beams. The concentrated stresses from the loaded area are superimposed on bending stresses in the beam. Timoshenko's Strength of Materials has more details.

corus

 

[Stress02]

If you are designing a slab on steel deck (floor form), United Steel Deck has a good design example. Check their website or order their deck catalog.