Moment redistribution in hybrid FRP–steel RC beams: proposed model incorporating relative stiffness
Yanan Wu,Bo Chen,Sergio M.R. Lopes,Adelino V. Lopes,Yi Dong,Tiejiong Lou
Abstract
For concrete beams reinforced with hybrid fiber reinforced polymer (FRP)–steel bars, prevailing codes typically employ the neutral axis depth (c/d) to quantify the degree of moment redistribution (B). Nonetheless, this parameter predominantly reflects sectional behavior and may not accurately capture global structural response. Furthermore, the inherent bond–slip between FRP and concrete significantly influences the moment redistribution characteristics of the structure. To address these deficiencies, this research develops a finite element (FE) model that explicitly incorporates bond–slip effects. An improved simplified model for predicting moment redistribution is also proposed, highlighting the influence of relative stiffness, expressed as pt1/pt2, where pt1 and pt2 represent the effective reinforcement ratios in the sagging and hogging moment regions, respectively. Numerical analyses demonstrate that the B is dictated not only by c/d, but is also strongly governed by pt1/pt2. Accordingly, the BSI model is modified to incorporate both c/d and pt1/pt2 as key parameters within the redistribution assessment framework. Comparative evaluation against FE model results confirms that the proposed simplified model significantly improves prediction accuracy for B, affirming its applicability and reliability for this class of beams.
Key Words
bond–slip; finite element model; hybrid FRP–steel bars; moment redistribution; simplified model
Address
Yanan Wu — Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Bo Chen — Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Sergio M.R. Lopes — CEMMPRE, ARISE, Faculty of Sciences and Technology, University of Coimbra, Coimbra 3030-788, Portugal
Adelino V. Lopes — INESC Coimbra, Department of Civil Engineering, University of Coimbra, Coimbra 3030-788, Portugal
Yi Dong — School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China
Tiejiong Lou — Sanya Science and Education Innovation Park, Wuhan University of Technology, Sanya, 572000, China; School of Civil Engineering and Architecture, Wuhan University of Technology, Wuhan, 430070, China; CEMMPRE, ARISE, Faculty of Sciences and Technology, University of Coimbra, Coimbra 3030-788, Portugal
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