The flexural design of Fiber-Reinforced-Concrete (FRC) tunnel linings typically uses a material-specific stress strain relationship (SSR) based on beam tests. The evaluation of beam tests to gain the SSR as well as the calculation of the bearing capacity of tunnel linings using a SSR is work intensive. The latter typically requires specialized software. Getting quick results for changed input parameters is therefore a challenge.The paper introduces design diagrams that allow, in a simple and quick manner, to either evaluate beam test results to gain the corresponding SSR or evaluate the bearing capacity of a tunnel lining for a given SSR in the Ultimate Limit State (ULS) or for the Serviceability Limit State (SLS). For given loading conditions, the diagrams can also be used to evaluate the required material properties, which can subsequently be used to assess the required fiber dosage. Therefore, the diagrams provide a powerful tool for a rough estimation and are considered very beneficial if quick results with very little effort are needed, i.e., during preliminary design stages, the bidding phase, or if the effect of changes of material properties, quality deficiencies or loading conditions need to be assessed. The paper discusses briefly the basics of FRC design and how the diagrams were developed. In addition, the paper provides design examples to explain the use of the introduced diagrams.
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