RF-/STEEL Fatigue Members Add-on Module for RFEM/RSTAB


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Fatigue Design of Members and Sets of Members

The RF-/STEEL Fatigue Members add‑on module allows you to perform fatigue designs according to EN 1993‑1‑9 for steel members and sets of members. The fatigue design is based on the nominal stress concept. The internal forces are determined according to the structural analysis for members. The stresses are calculated according to the mechanics of materials at the location where the crack formation is expected. This means that the ranges of nominal stress Δσ and Δτ as a result of the actions are contrasted with the design values of the fatigue strength ΔσR and ΔτR.

Furthermore, the concept of the partial safety values applies in EN 1993‑1‑9. The partial safety factor γMf for the fatigue strength is graded depending on the reliability concept and the possible consequences of failure.

The RF‑/STEEL Fatigue Members add-on module provides an extensive cross‑section library and an extendable material library including the strength values given by the standard.

  1. Features

    • Full integration in RFEM/RSTAB including import of all relevant information and internal forces
    • Determination of stress ranges for the available load cases, load or result combinations
    • Free assignment of detail categories on the available stress points of the cross-section
    • User-defined specification of damage equivalent factors
    • Design of members and sets of members according to EN 1993-1-9
    • Cross-section optimization with optional transfer to RFEM/RSTAB
    • Detailed result documentation with the references to design equations used
    • Various filter and sorting options of results including result lists by member, cross-section, x-location, or by load case, load and result combination
    • Visualization of design criterion on RFEM/RSTAB model
    • Data export to MS Excel
  2. 1.1 General Data


    After opening the module, it is necessary to define designed members/sets of members, load cases, load or result combinations for the fatigue strength design.

    The materials from RFEM/RSTAB are preset and can be adjusted in RF-/STEEL Fatigue Members. Material properties listed in the respective standard are stored in the material library.

    The design requires damage equivalent factors as well as detail categories on the designed stress points to be considered in the calculation.

  3. Design results for cross-section


    The fatigue strength design is based on the analysis using damage equivalent factors. The damage-equivalent stress ranges ΔσE,2 and ΔτE,2 in relation to 2*106 stress cycles are to be compared with the limit values of the fatigue strength ΔσC or ΔτC for 2*106 stress cycles of the corresponding detail category under consideration of the partial safety factors.

    In this way, the individual design requirements are specified. Separate design cases allow for flexible analysis of selected members, sets of members, and actions as well as of individual cross-sections. You can freely define design-relevant parameters such as the design concept selection or the partial safety factors.

  4. Results graphic with design ratio


    After the calculation, the module displays results in clearly arranged result windows. All intermediate values (for example governing internal forces, adjustment factors etc.) can be included in order to make the design more transparent. The results are listed by load case, cross-section, member, and set of members.

    If the analysis fails, the relevant cross-sections can be modified in an optimization process. It is also possible to transfer the optimized cross-sections to RFEM/RSTAB for a new calculation.

    Design ratio is represented with different colors in the RFEM/RSTAB model. In this way, you can quickly recognize critical or oversized areas of the cross-section. Furthermore, result diagrams displayed on the member or set of members ensure targeted evaluation.

    In addition to input and result data including design details shown in tables, you can add any graphic into the printout report. In this way, a comprehensible and clearly arranged documentation is guaranteed. You can select the report contents and results extent specifically for the individual designs.

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