My model is done by ABAQUS which is shear strengthening of RC beams with externally bonded FRP. I`m using tangential surface to surface interaction where the inputs are the shear stress limit after which slip will occur and normal behavior in which the default stiffness did not give good results. Can anyone help me. Thanks a lot
Dear Abdelrahman,
If you are interesting only in the ultimate state (Failure load) not the load-deformation relation, then you may simulate the FRP effect using external confiding pressure.
I used this simple technique in my attached research and it gave accurate results.
good luck
https://www.researchgate.net/publication/270449114_THEORETICAL_STUDY_FOR_RC_COLUMNS_STRENGTHENED_WITH_GFRP_WITH_DIFFERENT_MAIN_STEEL_RATIO?ev=prf_pub
Conference Paper THEORETICAL STUDY FOR R.C. COLUMNS STRENGTHENED WITH GFRP WI...
Dear Ahmed Ebid
Thanks for your answer. if i`m interested in the load- deflection curve would this simple technique gives accepted results for my problem or would it simulate the De-bonding .
Dear Abdelrahman,
If you are interesting in load-deformation curve, my simple technique will not give accurate results specially at small loads.
The problem is FRP has low elastic modulus comparing to its tensile capacity, in other words it needs large strain to archive the ultimate tensile stress, this large strain occurs only when the concrete failed after developing large cracks.Abaqus & Ansys will stop analysis just when the concrete fails and before developing the required large strain to develop tension in FRP.
I faced this problem in my research and solved it using external confining load (since I was interesting only in axial capacity not deformations), another colleague faced the same problem , she decided to split the beams in to 3 parts and join then with interface elements, the locations and slope of the separators between parts is per-determined from the geometry ( from point of applied load to point of support reaction). this procedure gives good matching with experimental results. see attached paper.
best wishes
https://www.researchgate.net/file.PostFileLoader.html?id=563fb5c05dbbbdfeec8b4577&assetKey=AS%3A293620004474880%401447015872536
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