Abstract

The first part of this article presents the results of an experimental researchexecuted on 42 high strength concrete columns. The parametric experimental study investigates the performance of high strength concrete columns under three loading levels 0.2, 0.4, and 0.6 subjected to moderate axial restraint degree = 0.1 and exposed to two heating rates. The second part of the article presents a three-dimensional finite element model of the reinforced concrete columns taking into account exposure to high temperatures. The effects of tension softening is included in the model and based on Hordijik, Cornelissen,and Rienhardt curve. The concrete columns were modeled taking into account the embedded reinforcement, and cracks formation using smeared cracks model which allowed a non-linear transient structural analysis to be conducted.The comparison of the results of the FEM and the performed tests showed a reasonable agreement and divergence in some cases due to concrete spalling. An assessment of the compressive stresses generated due to axial restraint under fire is also presented in the article. The experimental and the FEM study showed that imposing axial restraint against concrete columns expansion may reduce explosive spalling of concrete in fire.