FE analysis of behavior of steel fibre reinforced Ultra-high strength concrete columns Under reversed cyclic loading

Abstract

Although ultra-high strength concrete with steel fibre has been widely used for civil and architectural engineering, from the difficult of production of ultra-high strength concrete, very little test data was available for the study of characteristics of this material. Therefore, this paper presents results of FE modelling of failure behaviour of steel fibre reinforced ultra-high strength columns under slowly reversed cyclically induced lateral load(hysteric load), for the defining the characteristics of ultra-high strength concrete at various details. High strength concrete was modelled with elasto-plastic model using isotropic hardening and softening because ultra-high strength concrete have small sized-aggregate with homogeneity. Plasticity damaged model was used for the constitutive law for compression and tensile regime. For the simulation of compressive behaviour of ultra-high strength concrete, three uniaxial stress-strain relation and test data were used (AFGC, JSCE and Obata model). Uniaxial tensile behaviour was modelled with two bi-linear model(AFGC, JSCE) and one exponential model(Mansur model). These models well predict compressive and tensile behaviour of steel reinforced ultra-high strength concrete. Steel rebars were modelled with an elasto-plastic constitutive law with Von Mises yield criterion. The FE model was calculated using FEM code, ABAQUS. FE model was compared withpreviously conducted test data of fibre reinforced columns under reversed cyclic loading. Although FE model predicted high initial stiffness, ultimate load and other characteristics, such as crack propagation and strain concentration at the column-base surface was satisfactorily described. Using proposed FE model, parametric study was conducted. The main parameters are compressive strength of concrete, steel reinforcement ratio and axial load level. Higher compressive strength of concrete reduced energy dissipation area compared with normal strength concrete. Axial load increase lateral load capacity of column but reduce the ductility ratio. For more ductile manner optimal reinforcement was found in the case of 200MPA compressive strength of concrete.