A neuro-fuzzy approach to estimate the shear contribution of externally bonded FRP composites
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ORIGINAL PAPER
A neuro‑fuzzy approach to estimate the shear contribution of externally bonded FRP composites Swapnasarit Kar1 · A. R. Pandit1 · K. C. Biswal1 Received: 1 July 2020 / Accepted: 26 October 2020 © Springer Nature Switzerland AG 2020
Abstract The wide usage of fiber-reinforced polymer (FRP) composites as an external shear strengthening material have resulted in the development of various design guidelines. However, the accuracy of the design guidelines is a matter of concern since the shear behavior of the RC beam becomes more complex with the addition of FRP composites. On the other side, soft computing methods have been proved to be efficient enough to analyze complex systems. However, their application in structural engineering is limited. Therefore, in the current investigation, an effort has been made to evaluate the shear contribution of the EB-FRP composites with the help of adaptive neuro-fuzzy inference system (ANFIS). A total of 151 sets of data assembled from literature was utilized for the development and evaluation of the ANFIS model. The ANFIS predictions were validated against the obtained experimental results as well as with the estimations of six widely implemented design guidelines. The comparative study has shown that the ANFIS estimates are in decent agreement with that of experimental outcomes and the accurateness of the current ANFIS model is superior to the considered design guidelines. Finally, a parametric investigation was performed to explore the combined effect of various parameters as well as the impact of independent parameters. Keywords RC beam · ANFIS · FRP · Shear strengthening · Shear contribution List of symbols Af Area of the FRP reinforcement and Af = 2ntf wf bw Width of the RC beam d Effective depth of RC T-beam d0 Distance of extreme compression fiber from the centroid of the outermost layer of tensile reinforcements df Effective depth of FRP dv Effective depth in the CSA guidelines, maximum of 0.9d or 0.72 × overall depth of RC beam Ef Elastic modulus of FRP (MPa) (in GPa for fib) ffd/ffe Design strength/effective design strength of FRP fc Mean cylindrical compressive strength of concrete, as specified in the original article fctm Mean tensile strength of concrete KEN Covering coefficient kv Bond-reduction coefficient k1 Modification factor applied to kv to account for concrete strength
k2 Modification factor applied to kv to account for wrapping scheme Le Effective bond length n Number of FRP layers sf Center to center spacing of FRP strips pf Spacing of FRP strips, measured orthogonally to the fiber direction tf Thickness of FRP strip/sheet per layer wf Width of FRP strip/sheet z Internal lever arm α Angle in between principal fibers of FRP and the line perpendicular to the longitudinal axis of the member β Angle in between the longitudinal axis of the beam and principal fiber direction εf,e/εfu Effective/ultimate strain of FRP τmax Maximum bond strength θ Inclination of critical shear crack (assumed equal to 45°) ρf FRP reinforcem
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