Nonlinear finite element modeling of concrete confined by fiber composites

Since use of fiber composites for confirming concrete columns is relatively new, analytical models are limited to those of steel ties and hoops, which tend to overestimate the strength of cross section. A nonlinear finite element model with a non-associative Drucker-Prager plasticity is developed to account for restraint pressure sensitivity of concrete. The predicted stress-strain curves compare favorably with test results. Volumetric expansion tendency of confined concrete, however, is not preserved. The model shows stress concentrations around corners of square sections, as previously observed by the experiments. The stress concentration depends on corner radius. The model, however, does not allow for stiffness degradation under cyclic loading. (C) 2000 Elsevier Science B.V. All rights reserved.