Plate Analysis 1

[LIGWY]

I have a 3/8" plate that is span over a 26'x6' area and is supported every 4'3". The circumference is welded. I have a uniform load for the area at 2,200 lbs/ft or a 515 lbs/ft^2 and I also have a point load that is 4,985 lbs (there are two of them at 3' apart)

How do I go about analysis a plate for moment shear and deflection?

The formulas would really help and how the K or C factors are found.

 

[LIGWY]

The problem is where I live there is not a good library to go to I tried and I also do not have one day air here. I do appreciate all the help I can receive here. I do know I am out of my area and trying and I guess I DO HAVE the fear of what exactly you said that is why I do not want to wing it and all the PE's in my office are not aware either of how to solve it so I appreciate everything and I am doing my research so I know why and how this system will or will not work.

I hope you do not feel I am taking advantage of this forum because I believe there is great knowledge to be shared here

 

[aggman]

I guess I don't think you are taking advantage, but at some point the help from here has to stop and you have to get the books and teach yourself about it. Is someone going to sign off on this? It seems odd to me that your P.E.'s are not trying to figure it out since they would have to approve it. If you somehow get your hands on Roark's formula's for stress and strain it will tell you everything you need to know about your problem. It is one of those must have books for all structural offices.

 

[UcfSE]

I agree with aggman that you need to take what you have and do what you can. While we all do not mind helping, we cannot do it for you or engineer it for you and say "yes" or "no". You'll just have to get to a library or a book store or order one and have it delivered. If the library is not close, you have a long drive. If you cannot get immediate delivery from an online store, you'll have to order what you need and wait. That's not to be harsh or mean-spirited, but that's just how it is. You have to do what it takes to do the job that needs doing.

 

[LIGWY]

Thank You Everyone The Book Has Been On Order Since Friday Morning. I really do appreciate all the help

 

[rb1957]

ok, group hug !

now that we're over that; Abutler, i think the posters are pointing you in a direction. Roark is a fabulously detailed book; somewhere in it is the solution to your problem (though probably by superposition, and maybe by approximation). have a care about using the equations if you don't understand the underlying analysis; there could be assumptions that invalidate the answers (even if they came from Roark). This problem looks quite tricky, as large flat plates with out-of-plane loads tend to be (how much membrane reaction develops?)!

several posters have suggested that the stress induced is about 30 - 40ksi, which should be good for the plate (has anyone looked at the welds?), and possibly enough untill you can calc things for yourself. presumably you don't have a simple FE program on hand ? mind you, if you want to capture the membrane action, you're either in for a lot of modelling (projecting the originally flat plat onto a surface to account for deformation), or some reasonably sophisticated software (non-linear FE); or you can say "tell heck with this membrane stuff", and be conservative by considering a pinned supported plate.

you've had several suggestions about redesigning things if you want to. no-one has suggested a thicker plate, but if you're weight insensitive, maybe its a case of why not ? other suggestions (about stiffeners (integral or separate pieces) but adopting this depends upon your faciliaty (what can you do cheaply ? what do you care about in the design ?) and after several days of discussion, you let us know that the big point loads are moving, which obviously affects things.

good luck

 

[miecz]

You may want to consider impact from the moving load (is this a forklift?), and fatigue of welds.

 

[LIGWY]

I did have an impact factor involved and it is for moving fine soda ash material.