reading specs of crfp

[itez]

for example, sika has the following specs for 2 kinds of crfp

SikaWrap Hex-230C
Strength 4,100 Mpa
Stiffness 230 Gpa
Max. Strain % 1.7
Thickness mm 0.12
Areal Weight g/m^2 220

SikaWrap-103C
Strength 3,900 Mpa
Stiffness 230 Gpa
Max. Strain % 1.5
Thickness mm 0.34
Areal Weight g/m^2 610

Questions.

1. Is 4,100 Mpa for example for just one carbon strand (if not, how many)?
2. Max Strain of 1.7% for example means if it is stretched 1.7%. It breaks. So which do you think is better, 1.5% strain or 1.7%? I think 1.5% because it confines the concrete better, ins't it?

3. What is the tensile strength of say 4000 psi concrete? Do they match it with the strain of the fabric?

3. The sika103c is thicker, almost 3 times.. does it mean it is 3 times stronger even if it has similar tensile strength of say 4,100 Mpa with another model?

4. Area thick of sika103c is twice that of 230c. What significance is this?


Just want an idea of reading specs. Of course I know Crfp has its own unique calculations. What software is used for crfp anyway? Etabs? Staads? or purely manual?

Thanks.

 

[hokie66]

I'm no expert on carbon fibre, but your questions indicate that you do not have the basic understanding required to evaluate specifications. For instance,

1. MPa is a unit of stress, so is independent of area.
2. The tensile strength of concrete is many times less than your quoted 4100 MPa, in the order of 1/1000 of that number, but I don't know why that would be relevant.
3. Refer item 1.
4. One material is denser than the other.

 

[itez]

For 2, It's relevant in that in shear in beams, diagonal cracks occur. This can be resisted by the strain of the fabric in confining the shear diagonal cracks.

About 1. Right. 28 Mpa of concrete is same for any sizes of concrete. So in the carbon fiber.. since it's a sheet... then I wonder how is it measure when one dimension is so thin in the order of 0.1mm. How is 4000 mpa in a carbon fiber derived?

If one fabric is denser than the other. It means the individual fiber for the denser sheet is weaker? I haven't heard one concrete being denser than the other yet have same mpa.

 

[rb1957]

"then I wonder how is it measure when one dimension is so thin in the order of 0.1mm. How is 4000 mpa in a carbon fiber derived?" ... it (a laminate) has finite thickness (0.12mm), so 1 mm width (of 1 ply) of this can carry 4100*0.12 = 400N
the CFRP is basically a plastic resin with Very strong carbon fibers embedded in it.

remember, not all the sheets are oriented the same direction (90/45/0/-45/90) so the strength of the combined plies is very different.


Quando Omni Flunkus Moritati

 

[rb1957]

ok ... my math is off ... 400N should be 410+82 = 492N ... sigh

Quando Omni Flunkus Moritati

 

[itez]

Beam shear is in Vu. Let's say Vu is 50K. If the fiber can carry 50K or more. Does it mean it resist the Vu?

 

[rb1957]

depends on the ply lay-up ...

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