How do you obtain EA, EI, w, and v for a steel sheet pile section?

Dear Diogenes,

You are correct.

Provided that for steel E = 200E6 kN/m2 (I actually know it as 210E6 kN/m2) the PLAXIS values are:

- A = 1.92E-2 m2/2, so EA = 3.84E6 kN/m 

- EI as you computed equal to 828 kNm2/m

- w  = weight * thickness, which is typical for structures that occupy a significant volume.
For sheet piles you could use the unit weight directly and convert it to kN/m/m
then w = 1.48 kN/m/m

- Poisson's ratio is for steel is usually 0.2

By the way, in case you have not found it this might interest you:
communities.bentley.com/.../material-parameter-datasets-for-sheetpiles-and-beams

Good morning,

I'm trying to back calculate the value of unit weight, w as shown by Mr. Stefanos. May I know how the value of w = 1.48 kN/m/m was obtained for this example? I will be glad if you may able to show us the step by step. 

Besides that, I'm also trying to back calculate the value of EA1, EA2, EI and w as given in the SheetProfiles2D.matdb. I'm referring to AU14-430 in the database. May I know what is the value I should key in for t, h, A, I1, Esteel, and Unit weight of steel when using the spreadsheet?

Thanks.

Best regards,

Felix

Hi Felix, 

(I'm only explaining based on Plaxis 2D because I'm using only Plaxis 2D)

If you are going to model any structures using plates, the width can't be taken in the analysis unless you are using the volume element to model. so lets say for example you are analyzing 300mm thick vertical or horizontal concrete wall, here when using plate you can't provide 300mm width in the analysis, only you can provide a small line without any thickness actually. Then from the selfweight of the structure you need to reduce the weight of the soil which are present in the 300mm width if not the plate weight is providing additional load to the soil which in-turns provide some bearing issues in the soil. but this is possible when you using the plate to check the bending and shear forces where selfweight is perpendicular to bending moment and shear force loadings (Eg: diaphragm wall in deep excavations). Otherwise proper judgment considered in this section. 

Now let's move in your case, ie sheetpile wall. Basically sheetpile thickness is very small so the above effect is not very much critical here as selfweight of the soil of that small thickness can be neglected. 

Plate element provided in the plaxis is infinitely long in z-direction (as you know), so here properties should be defined per m length into the paper. 

In your questions you have asked about the PS 31 which have unitweight (per m pile length , plate property)  151.4 kg/m2. So to calculate the the unitweight it needed to be multiply by gravity acceleration and divide by 1000 that's give 1.48 kN/m/m (151.4 * 9.81 /1000). 

Here kN/m/m which indicates force per meter length along the y direction (if you consider the vertical wall) and per meter in the z-direction as plate is infinitely long along z- direction. 

Same you can use for calculating EA and EI, get the vlaues A and I per m pile length and multiply by E of the steel. Here A and I is define by the way of the bending of the system. No need to consider thickness here as the cross-section of the sheetpile is not linear, it is complex in shape 

The properties of the steel as per the EC 3 are shown below. 

Hope it will help and sorry about my English if any wrong as my mother tongue is not English. 

Thanks. 

Good Morning Guys,

How to make sure that steel sheet pile stiffness is correct? If the steel sheet pile is modeled as a plate element, the input parameters are only EA and EI. Then the equivalent thickness is automatically calculated to depend on input EA and EI where It is thicker than actual sheet pile thickness. I mean if we input EA and EI bigger, we can get higher stiffness, so the moment force along sheet pile can bigger otherwise but actually the sheet pile thickness is thin. I think we must modify the input parameters to get the proper moment. Please advise about the issue?

Thanks

Rustama Berangket