Steel Plate Design

[struggle67]

Hi everyone I'm a fresh graduate in civil engineering and now I'm doing a steel plate design which is 400mm wide, 35mm thick and it's simply supported.The span length is .25m.It's in flexural condition. It look like elementary but I don't know how to consider the width thickness ratio of the plate.If someone knows about steel plate design plz help me thz

 

[manstrom]

Is it flat?

If so, it's as easy as you think. M/S = fb

 

[par060]

the AISC steel manual specifies how you are to determine allowable bending

 

[briancpotter]

manstrom is correct, it's basic steel bending.

Brian C Potter, PE

http://simplesupports.wordpress.com

 

[fegenbush]

If is simply supported on two ends only, manstrom has your answer. If it is simply supported on all four sides, check Roark's Formulas for Stress and Strain.

 

[dik]

or check Blodgett... he has a formula, or look for Alex Tomanovitch's spreadsheet (loaded it... had to check for the spelling of his name).

The spreadsheet is excellent.

You can also use Z=bd^2/4 rather than bd^2/6 for section modulus...

Dik

 

[theonlynamenottaken]

It shouldn't matter much for this particular application, but as a fresh grad I'd recommend you get used to checking serviceability as well as strength. Calculating deflection for a plate should be very straightforward if your load is uniformly distributed pressure, and that's included in the spreadsheet dik posted.

 

[BAretired]

You can also use Z=bd^2/4 rather than bd^2/6 for section modulus...

If you use the Plastic Modulus, Z=bd^2/4, you would be using factored loads, right dik?

BA

 

[BAretired]

aungthu,
35mm seems like a pretty thick plate to be spanning 250mm. What type of load do you have on this plate?

BA

 

[frv]

BAretired,

No, dik is correct. The limit state is calculated independently of design method. For LRFD, the value is multiplied by 0.9; for ASD, it is divided by 1.67.

 

[BAretired]

Okay, frv thank you. In Canada, ASD is not recognized, so for LRFD or LSD (Limit States Design), factored loads would be used and compared with 0.9Fy*Z, correct?

BA

 

[dik]

Correct... BA, and although not common, WSD occasionally pops up.

Dik

 

[frv]

BARetired, I believe the "plastification" of the cross-section has always been accounted for in AISC, albeit indirectly. I don't have the previous (ASD) codes in front of me (and I am unfamiliar with them , as I begun with the 13th (combined) Edition), but I believe there was an increase allowed in the capacity for the Yielding limit state depending on the shape of the member under consideration.. this essentially accounted for the plastic section modulus.

 

[BAretired]

Now that you mention it frv, I believe a similar provision was in the Canadian code prior to the exclusive adoption of Limit States Design (LSD).

BA

 

[dik]

In addition to the plastification of the section, the section can be considered as a Class 1 section, generally permitting a higher stress level.

 

[BAretired]

I'm still wondering what type of load would require a 35 mm steel plate spanning 250 mm.

BA

 

[dik]

Big <G>

 

[struggle67]

Thank you all the plate is used for pretension work to grip the strands at both ends (stressing end and dead end)of the form work.There are fives holes in the plate to hold five strands with wedges. The prestressed force in each strand is 144 kN.Ive checked shear, deflection, flexural. Among them, flexural is control.I used plastic modulus Z.I just wanted to know what else I still need to check.

 

[dhengr]

You ask... “I just wanted to know what else I still need to check.”

One of the things you oughta check..., is to check back in here when you post a question, quickly and regularly, so there aren’t 16 guesses before you actually define your problem for the first time. And, drop the twitter speak/twitter spell and use regular engineering speak, full words and sentences. There are plenty of smart people here willing to help you with your problem, but you are wasting their time when you don’t make the effort to fully define your problem, so they know all the facts.

 

[BAretired]

I think you need to check flexural again. A 35mm plate does not work for the loads given.

BA