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Redistribution of moments in reinforced high-strength concrete beams with and without confinement

  • Lou, Tiejiong (CEMUC, Department of Civil Engineering, University of Coimbra) ;
  • Lopes, Sergio M.R. (CEMUC, Department of Civil Engineering, University of Coimbra) ;
  • Lopes, Adelino V. (Department of Civil Engineering, University of Coimbra)
  • Received : 2015.03.01
  • Accepted : 2015.06.16
  • Published : 2015.07.25

Abstract

Confinement is known to have important influence on ductility of high-strength concrete (HSC) members and it may therefore be anticipated that this parameter would also affect notably the moment redistribution in these members. The correctness of this "common-sense knowledge" is examined in the present study. A numerical test is performed on two-span continuous reinforced HSC beams with and without confinement using an experimentally validated nonlinear model. The results show that the effect of confinement on moment redistribution is totally different from that on flexural ductility. The moment redistribution at ultimate limit state is found to be almost independent of the confinement, provided that both the negative and positive plastic hinges have formed at failure. The numerical findings are consistent with tests performed on prototype HSC beams. Several design codes are evaluated. It is demonstrated that the code equations by Eurocode 2 (EC2), British Standards Institution (BSI) and Canadian Standards Association (CSA) can well reflect the effect of confinement on moment redistribution in reinforced HSC beams but the American Concrete Institute (ACI) code cannot.

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