Numerical study on triaxial compressive behavior of engineered cementitious composites confined by circular steel tubes

Abstract

The mechanism of engineered cementitious composites (ECC) in triaxial compression is still unclear, and the existing method cannot accurately predict its compressive capacity due to the lower elastic modulus and the effect of fiber bridging. In this paper, the compressive behavior of ECC confined by circular steel tubes was studied by performing a series of nonlinear finite element (FE) analysis. The non-linear material properties of ECC and steel and composite actions were considered in developing the FE models. The accuracy of the models was verified by comparison with the test results, such as load–displacement histories, failure modes and ultimate strengths. The verified model was utilized to explore contact pressure, the contribution of ECC to compressive capacity, ductility, energy absorption, and the influence of important parameters. Additionally, the effective confining stress (fr) was modified by average contact pressure, and a constitutive model of ECC under triaxial compression was developed by stress–strain relationships. It is shown that the effect of boundary confinement effect coefficient on the post-peak period of load–displacement history is classified and discussed. Meanwhile, the results of Richart’s model achieve a good accuracy by modifying the effective confining stress. Finally, a constitutive model of ECC under triaxial compression is proposed, of which the prediction results can describe the variation law of stress–strain relationship.