FINITE ELEMENT ANALYSIS ON LARGE-RUPTURE-STRAIN (LRS) FRP-CONFINED CONCRETE BASED ON MODIFIED CONCRETE DAMAGED PLASTICITY MODEL

Accurate finite element analysis (FEA) depends on the accurate definition of materials. The definition of material properties of large-rupture-strain fiber reinforced polymer (LRS FRP) in the fiber direction is realized by writing the user subroutine UMAT. Based on the theoretical framework of the concrete damaged plasticity model in Abaqus, a modified concrete damaged plasticity model is proposed to define the material properties of LRS FRP-confined concrete. These modifications include: the parameter K related to the yield criterion is calibrated by the test data of LRS FRP-confined concrete; the hardening/softening criterion is related to the confinement stiffness; the flow rule is related to axial plastic strain. The modified material model is used for FEA. The results show that the stress-strain curve predicted by FEA is consistent with the test results. Based on the FEA results, the non-uniform of stress distribution on the rectangular column section is discussed, which can be divided into effective confinement area and weak confinement area according to the confinement effect, and the non-uniform stress distribution in the effective confinement area increases with the increase of section ratio (the ratio of long side to short side).