FRP - Sh (Design Stress _ BS-7159)

Dear Srs.,

Just to have an idea, what is the mean value for the Sh (allowable design stress) used in BS-7159 code?

The pipe vendor provided a value equal to 14MPa. Very low, isn´t it?

Thank you very much.

Roberto

A value of 14 MPa for FRP allowable hoop stress seems low indeed. I would expect a value of approx 60-70 MPa or something like that. However you're bound to the information given by the pipe vendor as allowable stress depends on a lot of things, like for example winding angle and base materials used. If the pipe is made for non-pressurized usage the winding angle may be far of from 55 degrees and may provide much axial strength and less hoop strength.

As per section 4 clause 4.3.1 of BS7159

Allowable stress = axial design strain x axial modulus of elasticity.

properties will depend on manufacturing.

Ok, thank you you all.

So as per section 4 clause 4.3.1 of BS7159 my Sh will be:

Sh = 0,325% * 14572MPa = 47MPa (both parameters provided by the pipe vendor)

47MPa for Sh is more coherent!

Regards,
Roberto

Maybe the manufacturer isn't convinced about his material strength, or he has determined the allowables in a different way in comparison to BS7159. Without more information we can't solve this for you. Only thing I can say is that 14MPa is very low, 47MPa is average and about 60 to 70 MPa is expected in my opinion, see also my post above.

Oh right!

It helps me a lot.

Thank you very much.

Regards!