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Computers and Concrete Volume 4, Number 2, April 2007, pages 101-117 DOI: http://dx.doi.org/10.12989/cac.2007.4.2.101 |
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3D material model for nonlinear basic creep of concrete |
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Jorg Bockhold
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| Abstract | ||
| A new model predicting the nonlinear basic creep behaviour of concrete structures subjected to high multi-axial stresses is proposed. It combines a model based on the thermodynamic framework of the elasto-plastic continuum damage theory for time-independent material behaviour and a rheological model describing phenomenologically the long-term delayed deformation. Strength increase due to ageing is regarded. The general 3D solution for the creep theory is derived from a rate-type form of the uniaxial formulation by the assumption of associated creep flow and a theorem of energy equivalence. The model is able to reproduce linear primary creep as well as secondary and tertiary creep stages under high compressive stresses. For concrete in tension a simple viscoelastic formulation is applied. The material law is then incorporated into a finite element solution procedure for analysis of reinforced concrete structures. Numerical examples of uniaxial creep tests and concrete members show excellent agreement with experimental results. | ||
| Key Words | ||
| concrete; creep; damage; plasticity; finite-element analysis. | ||
| Address | ||
| ZERNA INGENIEURE, Engineering Consultants, Industriestrabe 27, 44892 Bochum, Germany | ||