Numerical evaluation of localization and softening behavior of concrete confined by steel tubes

摘要

A newly developed coupled numerical model is presented to investigate the compressive localization and softening behavior of concrete under steel tube confinement. The coupled model combines the use of rigid body spring model (RBSM) and nonlinear shell finite element method (FEM) to simulate concrete and steel in steel tube-confined concrete members. Numerical evaluation of compression localization in steel tube-confined concrete columns showed that the compressive behavior of this type of column is also localized and that the length of compressive fracture zone was found to be more localized in square cross section than equivalent circular cross section. With increasing slenderness and level of confinement, it was found that localization length increases with increasing confinement, and for higher confinement level, localization zone can only be observed in longer specimens. This means that localization and softening of concrete can always occur irrespective of confinement level but depends on the size (height) of the member.