This chapter covers the fundamental concepts of flow simulation and modeling of physical processes. Due to the high Reynolds numbers in wind engineering, directly solving the Navier-Stokes equations for viscous flows is not possible, which is why turbulent processes must be modeled. The focus is on representing time-varying phenomena, with methods ranging from steady RANS approaches to the more computationally intensive LES methods, which offer a more realistic depiction of flow conditions.
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Knowledge Base
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Knowledge Base
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Knowledge Base
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The RF-PIPING and RF-PIPING Design add-on modules allow you to design piping systems according to EN 13480-3 [1], ASME B31.1 and B31.3. In the case of the European standard, the determination of pipe stresses is based on the formulas of Section 12.3 Flexibility Analysis. Depending on the stress type, one or more resulting moments is applied without regard to each other. This differentiation occurs when determining the stresses due to occasional loads, for example.
Not all structural elements of a real building are included in a structural model. As an example, we can look at a pipe that runs along a steel girder frame.
It may become necessary to analyze pipe cross‑sections as surface models in plant engineering in particular, but also when analyzing details of structural systems. For this purpose, RFEM offers the option to create pipe cross‑sections automatically by means of a line.
In RFEM 5 and RSTAB 8, it is possible to assign nonlinearities to member hinges. In addition to the nonlinearities "Fixed if" and "Partial activity", you can select "Diagram". If you select the "Diagram" option, you have to specify the according settings for the activity of the member hinge. For the individual definition points, it is necessary to specify the abscissa and ordinate values (deformations or rotations and the according internal forces) that define the hinge.
After activating the RF‑PIPING add‑on module, a new toolbar is available in RFEM and the project navigator and tables are extended. The piping system is now modeled in the same way as the members. Pipe bends are defined simultaneously by tangents (straight pipe sections) and radius. Thus, it is easy to subsequently change bend parameters.
It is also possible to extend the piping subsequently by defining special components (expansion joints, valves, and others). The implemented libraries of structural components facilitate the definition.
Continuous pipe sections are defined as sets of piping systems.
For piping loads, member loads are assigned to the respective load cases. The combination of loads is included in piping load combinations and result combinations.
After the calculation, you can display deformations, member internal forces, and support forces graphically or in tables.
Pipe stress analysis according to standards can then be performed in the RF‑PIPING Design add‑on module. You only need to select the relevant sets of piping systems and load situations.
After modeling piping systems in RFEM using RF‑PIPING and defining loads as well as load and result combinations, you can carry out pipe stress analysis in the RF‑PIPING Design add‑on module.
You can select all or only some pipelines and loads, load or result combinations for piping design. The material library provides various materials according to EN 13480‑3, ASME B31.1‑2012, and ASME B31.3‑2012 standards.
After the calculation, the results are displayed in clearly arranged windows; for example, by cross‑section, by pipeline, or by members. You can also display the design ratio graphically on the entire model in RFEM. This way, you can quickly recognize critical or oversized areas of the cross-section.
In addition to the input and result data, including design details displayed in tables, you can add all graphics into the printout report. This way, comprehensible and clearly arranged documentation is guaranteed. You can select the report contents and extent specifically for the individual designs.
- Design according to EN 13480-3, ASME B31.1-2012, and ASME B31.3-2012
- Check of the minimum required wall thickness of the pipes, taking into account manufacturing allowances, corrosion, and welding factor
- Analysis of stresses due to sustained loads, sustained and occasional loads as well as due to thermal expansion
- Result documentation with tables and graphics in the RFEM printout report
- Graphical input of piping systems and piping components
- Illustrative visualization of piping systems and piping components in RFEM graphic window
- Comprehensive libraries for piping cross‑sections and materials
- Comprehensive libraries for flanges, reducers, tees, and expansion joints
- Consideration of piping structure (insulation, lining, tin‑plate)
- Automatic calculation of stress intensification factors and flexibility factors
- Specific piping action categories for load cases
- Optional automatic combinatorics of load cases
- Consideration of material properties (modulus of elasticity, coefficient of thermal expansion) either during operating temperature (default setting) or during reference (assembly) temperature of material
- Consideration of strain and uplift due to pressure (Bourdon effect)
- Interaction between the supporting structure and the piping system
Is it possible to analyze and design piping systems with Dlubal Software?
Why is it not possible to load the OPE combinations in the RF‑PIPING Design add-on module?
Is it possible to consider the eccentricity of unsymmetrical line welds for the stress analysis in RFEM 6?
I design pipelines using the RF-PIPING Design add-on module. I have created a new prestress load case and loaded the piping with longitudinal displacement. Is it possible to add this new load case to combinations that are generated automatically?
In the case of stairs with a complicated geometry, it is often difficult to design welds by using the analytical methods. How can I do this with RFEM?
How do I activate pipeline modeling?
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