Tensile & Compressive action on a plate 1

[Frustrated_Form]

Hi,

Could someone please help me i'm trying to understand how Ft and Fc (kN) are achieved in the attached table. The table has the other know values but I cannot seem to confirm the figures for Ft and Fc and don't wish to take them as gospel.

From the diagram I know:
Ft= Tensile Action
Fs= Shear action
L= Length (mm)
Fc= Compressive action
Si= Operating load (This is always 10kN)
H= Height (This is always 35mm)

 

[rb1957]

well Ft (and Fc) are functions of L ... graph to understand (looks linear).

I'd've thought it would be Ft*2L = S*H ... but it isn't ??

another day in paradise, or is paradise one day closer ?

 

[Frustrated_Form]

jec67 you are a star.

 

[jec67]

I deleted my post. I don't believe it was correct. I mistook L as the full length of the horizontal member, but he sketch indicates it is not.

That said, a question I do have are the support conditions are? It appears it is simply supported at the ends? However; there are values reported for Ft/fix, etc. - what are these?

 

[Frustrated_Form]

Jec67 it was right though

Ft=(Si*H)/L for some reason the first result is wrong but this is probably rounding. All the rest of the results work for that.

 

[jec67]

My original post (since delted) is wrong: rb1957's formula is correct. The length is 2L (assuming the vertical member is at the midspan of the horizontal member.

can you provide some more info about this table 9source, what is L1xL2 referring to, end conditions, etc.?

 

[rb1957]

yes, the table seems to work (incorrectly) on S*H/L (except for a round-off in the first line)

another day in paradise, or is paradise one day closer ?

 

[Frustrated_Form]

L1 and L2 are the length and width of the plate. So depending on the orientation of the plate the Ft changes.

ie (10x0.035)=350 /0.25 = 1.4kN

That works for them all except the 2.4kN figure which is 2.333kN

 

[Frustrated_Form]

rb1957 is this because Fc is the inverse figure?

 

[rb1957]

yes, that's the table math, but the table is incorrect, should be SH/(2*L)

another day in paradise, or is paradise one day closer ?

 

[rb1957]

no. Ft calc'd by taking moments about the other end ... S*H = Ft*(2L)

alternatively you can take moments about the middle (or anywhere) and have moment contributions from both Ft and Fc ...
S*H = Ft*L+Fc*L; but Ft = Fc so S*H = Ft*2L

another day in paradise, or is paradise one day closer ?

 

[Frustrated_Form]

Thank you for all of the help.