In the Geotechnical Analysis add-on, the Hoek-Brown material model is available. The model shows linear-elastic ideal-plastic material behavior. Its nonlinear strength criterion is the most common failure criterion for stone and rocks.
You can enter the material parameters using
Rock parameters directly, or alternatively via
GSI classification.
Detailed information about this material model and the definition of the input in RFEM can be found in the respective chapter Hoek-Brown Model of the online manual for the Geotechnical Analysis add-on.
In the Construction Stages Analysis (CSA) add-on, you can use built-up cross-sections by means of what are known as phase sections. This allows you to activate and deactivate the parts of the "Parametric - Massive II" section type throughout the construction stages.
Enter and model a soil solid directly in RFEM. You can combine the soil material models with all common RFEM add-ons.
This allows you to easily analyze the entire models with a complete representation of the soil-structure interaction.
All parameters required for the calculation are automatically determined from the material data that you have entered. The program then generates the stress-strain curves for each FE element.
Have you created the entire structure in RFEM? Very well, now you can assign the individual structural components and load cases to the corresponding construction stages. In each construction stage, you can modify release definitions of members and supports, for example.
You can thus model structural modifications, such as those that occur when bridge girders are successively grouted or when columns are settled. Then, assign the load cases created in RFEM to the construction stages as permanent or non-permanent loads.
Did you know that The combinatorics allows you to superimpose the permanent and non-permanent loads in load combinations. In this way, it is possible for you to determine the maximum internal forces of different crane positions or to consider temporary mounting loads available in one construction stage only.
Simple definition of construction stages in the RFEM structure including visualization
Adding, removing, modifying, and reactivating member, surface, and solid elements and their properties (for example, member and line hinges, degrees of freedom for supports, and so on)
Automatic and manual combinatorics with load combinations in the individual construction stages (for example, to consider mounting loads, mounting cranes, and other loads)
Consideration of nonlinear effects such as tension member failure or nonlinear supports
If there are geometry differences arising between the ideal and the deformed structural system from the previous construction stage, they are compared in the program. The next construction stage is built on top of the stressed system from the previous construction stage. This calculation is nonlinear.
Compared to the RF‑/STAGES add-on module (RFEM 5), the following new features have been added to the Construction Stages Analysis (CSA) add-on for RFEM 6:
Consideration of construction stages at RFEM level
Integration of the construction stage analysis into the combinatorics in RFEM
Additional structural elements, such as line hinges, are supported
Analysis of alternative construction processes in a model
Was the calculation successful? Now you can view the results of the individual construction stages graphically and in tables in RFEM. Moreover, RFEM allows you to consider the construction stages in the combinatorics and include it in further design.
The modal relevance factor (MRF) can help you to assess to which extent specific elements participate in a specific mode shape. The calculation is based on the relative elastic deformation energy of each individual member.
The MRF can be used to distinguish between local and global mode shapes. If multiple individual members show significant MRF (for example, > 20%), the instability of the entire structure or a substructure is very likely. On the other hand, if the sum of all MRFs for an eigenmode is around 100%, a local stability phenomenon (for example, buckling of a single bar) can be expected.
Furthermore, the MRF can be used to determine critical loads and equivalent buckling lengths of certain members (for example, for stability design). Mode shapes for which a specific member has small MRF values (for example, < 20%) can be neglected in this context.
The MRF is displayed by mode shape in the result table under Stability Analysis → Results by Members → Effective Lengths and Critical Loads.
The Dlubal structural analysis software does a lot of work for you. The input parameters, which are relevant for the selected standards, are suggested by the program in accordance with the rules. Furthermore, you can enter response spectra manually.
Load cases of the type Response Spectrum Analysis define the direction in which response spectra act and which eigenvalues of the structure are relevant for the analysis. In the spectral analysis settings, you can define details for the combination rules, damping (if applicable), and zero-period acceleration (ZPA).
If there is a load case or load combination in the program, the stability calculation is activated. You can define another load case in order to consider initial prestress, for example.
For this, you need to specify whether to perform a linear or nonlinear analysis. Depending on the case of application, you can select a direct calculation method, such as the Lanczos method or the ICG iteration method. Members not integrated in surfaces are usually displayed as member elements with two FE nodes. With such elements, the program cannot determine the local buckling of single members. That's why you have the option to divide members automatically.
Compared to the RF-/DYNAM Pro - Equivalent Loads add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Response Spectrum Analysis add-on for RFEM 6 / RSTAB 9:
Response spectra of numerous standards (EN 1998, DIN 4149, IBC 2018, and so on)
User-defined response spectra or those generated from accelerograms
Direction-relative response spectrum approach
Results are stored centrally in a load case with underlying levels to ensure clarity
Accidental torsional actions can be taken into account automatically
Automatic combinations of seismic loads with the other load cases for use in an accidental design situation
Entering soil layers for soil samples is performed in a clearly arranged dialog box. A corresponding graphical representation supports clarity and makes checking the input user-friendly.
An extensible database facilitates the selection of soil material properties. The Mohr-Coulomb model as well as a nonlinear model with stress and strain dependent stiffness are available for a realistic modeling of the soil material behavior.
You can define any number of soil samples and layers. The soil is generated from all entered samples using 3D solids. Assignment to the structure is carried out using coordinates.
The soil body is calculated according to the nonlinear iterative method. The calculated stresses and settlements are displayed graphically and in tables.
The load cases of the type Response Spectrum Analysis contain the generated equivalent loads. First, the modal contributions have to be superimposed with the SRSS or CQC rule. In this case, you can use the signed results based on the dominant mode shape.
Afterwards, the directional components of earthquake actions are combined with the SRSS or the 100% / 30% rule.
Did you know? You can enter the soil layers that you have obtained from the subsoil expertises done in the locations into the program in the form of soil samples. Assign the explored soil materials, including their material properties, to the layers.
For the definition of the samples, you can enter the data in tables as well as in the respective editing dialog box. Furthermore, you can also specify the groundwater level in the soil samples.
As the first results, the program presents you with the critical load factors. You can then perform an evaluation of stability risks. For member models, the resulting effective lengths and critical loads of the members are displayed to you in tables.
Use the next result window to check the normalized eigenvalues sorted by node, member, and surface. The eigenvalue graphic allows you to evaluate the buckling behavior. This makes it easier for you to take countermeasures.
You already know that it is possible to model and analyze a soil and a structure in the entire model. As a result, you have explicitly taken into account the soil-structure interaction. By modifying a component, you achieve the immediate correct consideration in the analysis as well as in the results for the entire system of the soil and structure.