FRP under reinforced concrete beam

[mehabb]

Is it possible to model concrete beam sections (rectangular) with FRP laminet layer under it? plaease kindley tell me wich section type must be used and how.

Thanks

[seismosoft]

yes, of course, search this Forum for "frp".

Seismosoft Support

[fakharifar.mostafa]

How can I specify an explicit strain limit as effective FRP rupture strain (considering debonding of FRP laminates) for the frp_tl material. I somehow tried to incorporate the ultimate rupture strain by increasing the Post-peak stiffness to a large value (negative value), as it apparently reduces the strain, however, it seems it can't be reduced lesser than 0.01.

I know performance criteria for the frp could be used, but I rather need to reflect the frp rupture in the force-displacement curve. Thanks.

[seismosoft]

What do you mean you could not reduce it less than 0.01? Which is the strain that you could not reduce?
Note that the ultimate strain is determined by the negative stiffness, but also by the (strain at peak)=(tensile strength)/(initial stiffness)

Seismosoft Support

[fakharifar.mostafa]

Thanks. I know your point, but I was trying to capture the residual post-ruture of the FRP material, thus was thinking of using two strain values (strain at peak and ultimate strain for residual strength).

[seismosoft]

The residual strength of the material model is zero, which is in accordance with the the typical behaviour of FRPs, i.e. brittle failure.
If we are not mistaken you are looking for a model similar to con_trl but in tension, rather than compression, right? Unfortunately, such a model is not available in the current release.

Seismosoft Support

[fakharifar.mostafa]

Yes, that's correct. I was not referring to the linear eleastic FRP material's behavior. I was considering a model like con_trl in tension, where member's residual response upon frp's rupture could be somehow tweaked. Anyhow, thanks for your reply to my concern.