Techno Press
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Computers and Concrete   Volume 19, Number 5, May 2017, pages 477-488
Analysis of actively-confined concrete columns using prestressed steel tubes
Mahdi Nematzadeh and Akbar Haghinejad

Abstract     [Full Text]
    In this paper, an innovative technique for finite element (FE) modeling of steel tube-confined concrete (STCC) columns with active confinement under axial compressive loading is presented. In this method, a new constitutive model for the stress-strain relationship of actively-confined concrete is proposed. In total, 14 series of experimental STCC stub columns having active confinement were modeled using the ABAQUS software. The results obtained from the 3D model including the compressive strength at the initial peak point and failure point, as well as the axial and lateral stress-strain curves were compared with the experimental results to verify the accuracy of the 3D model. It was found that there existed a good agreement between them. A parametric study was conducted to investigate the effect of the concrete compressive strength, steel tube wall thickness, and pre-stressing level on the behavior of STCC columns with active confinement. The results indicated that increasing the concrete core\'s compressive strength leads to an increase in the compressive strength of the active composite column as well as its earlier failure. Furthermore, a reduction in the tube external diameter-to-wall thickness ratio affects the axial stress-strain curve and the confining pressure, while increasing the pre-stressing level has a negligible effect on the two.
Key Words
    concrete constitutive models; confined concrete; finite elements method; pre-tensioned concrete; computer modeling
Mahdi Nematzadeh and Akbar Haghinejad: Department of Civil Engineering, University of Mazandaran, Babolsar, Iran

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