| Abstrakt: |
This article explains the time‐dependent parameters critical to the performance of post‐tensioned concrete structures, as treated in the design codes and practiced by design engineers, with an emphasis on recent developments in the field. Following an introduction to the application of time‐dependent analysis in post‐tensioned construction and to the technical requirements for its successful utilization, the treatment of time‐dependent parameters in model codes is presented. The discussion then introduces the basics for the practical implementation of creep, shrinkage, aging of concrete and relaxation in prestressing in the context of code requirements. The application of laboratory‐generated data is also discussed, for materials not adequately covered in the codes such as high performance concrete. Finally, the paper outlines a modern analytical technique for the structural modeling of prestressing tendons and its advantages over previous methods. The method yields an integrated solution, inclusive of all time‐dependent phenomena. The new method eliminates the need for a separate analysis to determine immediate and long‐term losses in prestressing because the losses become an integral part of the overall structural analysis. |
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