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.
You can select several methods that are available for the eigenvalue analysis:
- Direct Methods
- The direct methods (Lanczos [RFEM], roots of characteristic polynomial [RFEM], subspace iteration method [RFEM/RSTAB], and shifted inverse iteration [RSTAB]) are suitable for small to medium-sized models. You should only use these fast solver methods if your computer has a larger amount of memory (RAM).
- ICG Iteration Method (Incomplete Conjugate Gradient [RFEM])
- In contrast, this method only requires a small amount of memory. Eigenvalues are determined one after the other. It can be used to calculate large structural systems with few eigenvalues.
Use the Structure Stability add-on to perform a nonlinear stability analysis using the incremental method. This analysis delivers close-to-reality results also for nonlinear structures. The critical load factor is determined by gradually increasing the loads of the underlying load case until the instability is reached. The load increment takes into account nonlinearities such as failing members, supports and foundations, and material nonlinearities. After increasing the load, you can optionally perform a linear stability analysis on the last stable state in order to determine the stability mode.
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.
- Calculation of models consisting of member, shell, and solid elements
- Nonlinear stability analysis
- Optional consideration of axial forces from initial prestress
- Four equation solvers for an efficient calculation of various structural models
- Optional consideration of stiffness modifications in RFEM/RSTAB
- Determination of a stability mode greater than the user-defined load increment factor (Shift method)
- Optional determination of the mode shapes of unstable models (to identify the cause of instability)
- Visualization of the stability mode
- Basis for determining imperfection
- General stress analysis
- Automatic import of internal forces from RFEM/RSTAB
- Graphical and numerical output of stresses, strains, clearance, and design ratios fully integrated in RFEM/RSTAB
- User-defined specification of the limit stress
- Summary of similar structural components for the design
- Wide range of customization options for graphical output
- Clearly arranged result tables for a quick overview after the design
- Simple traceability of the results due to the complete documentation of the calculation method including all formulas
- High productivity due to the minimal amount of input data required
- Flexibility due to detailed setting options for basis and extent of calculations
- Gray zone display for unimportant value ranges (see Product Feature)
- Cross-section optimization
- Transfer of optimized sections to RFEM/RSTAB
- Design of any thin-walled section from RSECTION
- Representation of a stress diagram on a section
- Determination of normal, shear, and equivalent stresses
- Output of stress components for the individual member internal force types
- Detailed representation of stresses in all stress points
- Determination of the largest Δσ for each stress point (for example, for fatigue design)
- Colored display of stresses and design ratios for a quick overview of the critical or oversized zones
- Output of parts lists
- Determination of principal and basic stresses, membrane and shear stresses, as well as equivalent stresses and equivalent membrane stresses
- Stress analysis for structural surfaces including simple or complex shapes
- Equivalent stresses calculated according to different approaches:
- Shape modification hypothesis (von Mises)
- Shear stress hypothesis (Tresca)
- Normal stress hypothesis (Rankine)
- Principal strain hypothesis (Bach)
- Optional optimization of surface thicknesses and data transfer to RFEM
- Output of strains
- Detailed results of individual stress components and ratios in tables and graphics
- Filter function for solids, surfaces, lines, and nodes in tables
- Transversal shear stresses according to Mindlin, Kirchhoff, or user-defined specifications
- Stress evaluation for welds at connection lines between surfaces (see the Product Feature)
After you have completed the design, the program takes care of clearly arranged results. Thus, the program shows you the resulting maximum stresses and stress ratios sorted by section, member/surface, solid, member set, x-location, and so on. In addition to the tabular result values, the add-on shows you the corresponding cross-section graphic with stress points, stress diagram, and values as well. You can relate the design ratio to any kind of stress type. The current location is highlighted in the RFEM/RSTAB model.
In addition to the tabular evaluation, the program offers you even more. You can also graphically check the stresses and design ratios on the RFEM/RSTAB model. It is possible for you to adjust the colors and values individually.
The display of result diagrams of a member or set of members enables you a targeted evaluation. For each design location, you can open the respective dialog box to check the design-relevant section properties and stress components of any stress point. Finally, you have the option of printing the corresponding graphic, including all design details.
- A wide range of available sections, such as rolled I-sections; channel sections; T-sections; angles; rectangular and circular hollow sections; round bars; symmetrical and asymmetrical, parametric I-, T-, and angle sections; built-up cross-sections (suitability for design depends on the selected standard)
- Design of general RSECTION cross-sections (depending on the design formats available in the respective standard); for example, equivalent stress design
- Design of tapered members (design method depending on the standard)
- Adjustment of the essential design factors and standard parameters is possible
- Flexibility due to detailed setting options for basis and extent of calculations
- Fast and clear results output for an immediate overview of the result distribution after the design
- Detailed output of the design results and essential formulas (comprehensible and verifiable result path)
- Numerical results clearly arranged in tables and graphical display of the results in the model
- Integration of the output into the RFEM/RSTAB printout report
- Design of tension, compression, bending, shear, torsion, and combined internal forces
- Tension design with consideration of a reduced section area (for example, hole weakening)
- Automatic classification of cross-sections to check local buckling
- Internal forces from the calculation with Torsional Warping (7 DOF) are taken into account by means of the equivalent stress check (currently not for the design standards AISC 360‑16 and GB 50017).
- Design of cross-sections of Class 4 with effective cross-section properties according to EN 1993‑1‑3 (licenses for RSECTION and Effective Sections are required for the RSECTION cross-sections)
- Shear buckling check according to EN 1993‑1‑5 with consideration of transverse stiffeners
- Design of stainless steel components according to EN 1993‑1‑4
- Stability analyses for flexural buckling, torsional buckling, and flexural-torsional buckling under compression
- Import of the effective lengths from the calculation using the Structure Stability add-on
- Graphical input and check of the defined nodal supports and effective lengths for stability analysis
- Lateral-torsional buckling analysis of the structural components subjected to moment loading
- Depending on the standard, a choice between user-defined input of Mcr, analytical method from the standard, and use of internal eigenvalue solver
- Consideration of a shear panel and a rotational restraint when using the eigenvalue solver
- Graphical display of a mode shape if the eigenvalue solver was used
- Stability analysis of structural components with the combined compression and bending stress, depending on the design standard
- Comprehensible calculation of all necessary coefficients, such as the factors for considering moment distribution or interaction factors
- Alternative consideration of all effects for the stability analysis when determining internal forces in RFEM/RSTAB (second-order analysis, imperfections, stiffness reduction, possibly in combination with the Torsional Warping (7 DOF) add-on)
You enter the structural system and calculate the internal forces in the programs RFEM and RSTAB. You have full access to the extensive material and cross-section libraries. Did you know? You can also use the RSECTION program to create general cross-sections.
You find Steel Design fully integrated in the main programs. They automatically take into account the structure and the available calculation results. You can assign further entries for the aluminum design, such as effective lengths, cross-section reductions, or design parameters, to the objects to be designed. At many places of the program, you can easily select the elements graphically using the [Select] function.
- For the design according to Eurocode 3, the parameters of the National Annexes (NA) are integrated for the following countries:
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DIN EN 1993-1-1/NA:2016-04 (Germany)
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ÖNORM EN 1993-1-1/NA:2015-12 (Austria)
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SN EN 1993-1-1/NA:2016-07 (Switzerland)
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BDS EN 1993-1-1/NA:2015-10 (Bulgaria)
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BS EN 1993-1-1/NA:2016-07 (United Kingdom)
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CEN EN 1993-1-1/2015-06 (European Union)
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CYS EN 1993-1-1/NA:2015-07 (Cyprus)
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CZE EN 1993-1-1/NA:2016-06 (Czech Republic)
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DS EN 1993-1-1/NA:2015-07 (Denmark)
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ELOT EN 1993-1-1/NA:2017-01 (Greece)
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EVS EN 1993-1-1/NA:2015-08 (Estonia)
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HRN EN 1993-1-1/NA:2016-03 (Croatia)
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I S. EN 1993-1-1/NA:2016-03 (Ireland)
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ILNAS EN 1993-1-1/NA:2015-06 (Luxembourg)
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IST EN 1993-1-1/NA:2015-11 (Iceland)
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LST EN 1993-1-1/NA:2017-01 (Lithuania)
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LVS EN 1993-1-1/NA:2015-10 (Latvia)
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MS EN 1993-1-1/NA:2010-01 (Malaysia)
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MSZ EN 1993-1-1/NA:2015-11 (Hungary)
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NBN EN 1993-1-1/NA:2015-07 (Belgium)
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NEN EN 1993-1-1/NA:2016-12 (Netherlands)
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NF EN 1993-1-1/NA:2016-02 (France)
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NP EN 1993-1-1/NA:2009-03 (Portugal)
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NS EN 1993-1-1/NA:2015-09 (Norway)
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PN EN 1993-1-1/NA:2015-08 (Poland)
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SFS EN 1993-1-1/NA:2015-08 (Finland)
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SIST EN 1993-1-1/NA:2016-09 (Slovenia)
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SR EN 1993-1-1/NA:2016-04 (Romania)
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SS EN 1993-1-1/NA:2019-05 (Singapore)
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SS EN 1993-1-1/NA:2015-06 (Sweden)
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STN EN 1993-1-1/NA:2015-10 (Slovakia)
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TKP EN 1993-1-1/NA:2015-04 (Belarus)
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UNE EN 1993-1-1/NA:2016-02 (Spain)
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UNI EN 1993-1-1/NA:2015-08 (Italy)
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- The design according to US standard AISC 360 includes analysis methods according to:
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Load and Resistance Factor Design (LRFD)
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Allowable Stress Design (ASD)
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The parameters of the National Annexes (NA) to Eurocode 3 of the following countries are integrated:
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DIN EN 1993-1-1/NA:2016-04 (Germany)
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ÖNORM EN 1993-1-1/NA:2015-12 (Austria)
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SN EN 1993-1-1/NA:2016-07 (Switzerland)
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BDS EN 1993-1-1/NA:2015-10 (Bulgaria)
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BS EN 1993-1-1/NA:2016-07 (United Kingdom)
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CEN EN 1993-1-1/2015-06 (European Union)
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CYS EN 1993-1-1/NA:2015-07 (Cyprus)
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CSN EN 1993-1-1/NA:2016-06 (Czech Republic)
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DS EN 1993-1-1/NA:2015-07 (Denmark)
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ELOT EN 1993-1-1/NA:2017-01 (Greece)
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EVS EN 1993-1-1/NA:2015-08 (Estonia)
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HRN EN 1993-1-1/NA:2016-03 (Croatia)
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I S. EN 1993-1-1/NA:2016-03 (Ireland)
-
ILNAS EN 1993-1-1/NA:2015-06 (Luxembourg)
-
IST EN 1993-1-1/NA:2015-11 (Iceland)
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LST EN 1993-1-1/NA:2017-01 (Lithuania)
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LVS EN 1993-1-1/NA:2015-10 (Latvia)
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MS EN 1993-1-1/NA:2010-01 (Malaysia)
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MSZ EN 1993-1-1/NA:2015-11 (Hungary)
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NBN EN 1993-1-1/NA:2015-07 (Belgium)
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NEN EN 1993-1-1/NA:2016-12 (Netherlands)
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NF EN 1993-1-1/NA:2016-02 (France)
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NP EN 1993-1-1/NA:2009-03 (Portugal)
-
NS EN 1993-1-1/NA:2015-09 (Norway)
-
PN EN 1993-1-1/NA:2015-08 (Poland)
-
SFS EN 1993-1-1/NA:2015-08 (Finland)
-
SIST EN 1993-1-1/NA:2016-09 (Slovenia)
-
SR EN 1993-1-1/NA:2016-04 (Romania)
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SS EN 1993-1-1/NA:2019-05 (Singapore)
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SS EN 1993-1-1/NA:2015-06 (Sweden)
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STN EN 1993-1-1/NA:2015-10 (Slovakia)
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TKP EN 1993-1-1/NA:2015-04 (Belarus)
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UNE EN 1993-1-1/NA:2016-02 (Spain)
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UNI EN 1993-1-1/NA:2015-08 (Italy)
Was your design successful? Just sit back and relax. The program gives you the performed design checks in tables. All result details are displayed for you and you can easily follow them using the clearly arranged design formulas.
The design checks are carried out at all governing locations of the members. A graphical display is provided as a result diagram. Furthermore, you have access to detailed graphics, such as the stress distribution on a cross-section or the governing mode shape, available in the result output.
All input and result data are part of the RFEM/RSTAB printout report. You can select the report contents and extent specifically for the individual design checks.
- Automatic consideration of masses from self-weight
- Direct import of masses from load cases or load combinations
- Optional definition of additional masses (nodal, linear, or surface masses, as well as inertia masses) directly in the load cases
- Optional neglect of masses (for example, mass of foundations)
- Combination of masses in different load cases and load combinations
- Preset combination coefficients for various standards (EC 8, SIA 261, ASCE 7,...)
- Optional import of initial states (for example, to consider prestress and imperfection)
- Structure Modification
- Consideration of failed supports or members/surfaces/solids
- Definition of several modal analyses (for example, to analyze different masses or stiffness modifications)
- Selection of mass matrix type (diagonal matrix, consistent matrix, unit matrix), including user-defined specification of translational and rotational degrees of freedom
- Methods for determining the number of mode shapes (user-defined, automatic - to reach effective modal mass factors, automatic - to reach the maximum natural frequency - only available in RSTAB)
- Determination of mode shapes and masses in nodes or FE mesh points
- Results of eigenvalue, angular frequency, natural frequency, and period
- Output of modal masses, effective modal masses, modal mass factors, and participation factors
- Masses in mesh points displayed in tables and graphics
- Visualization and animation of mode shapes
- Various scaling options for mode shapes
- Documentation of numerical and graphical results in printout report
In the modal analysis settings, you have to enter all data that are necessary for the determination of the natural frequencies. These are, for example, mass shapes and eigenvalue solvers.
The Modal Analysis add-on determines the lowest eigenvalues of the structure. Either you adjust the number of eigenvalues or let them determined automatically. Thus, you should reach either effective modal mass factors or maximum natural frequencies. Masses are imported directly from load cases and load combinations. In this case, you have the option to consider the total mass, load components in the global Z-direction, or only the load component in the direction of gravity.
You can manually define additional masses at nodes, lines, members, or surfaces. Furthermore, you can influence the stiffness matrix by importing axial forces or stiffness modifications of a load case or load combination.
In RFEM, you can use these three powerful eigenvalue solvers:
- Root of Characteristic Polynomial
- Method by Lanczos
- Subspace Iteration
RSTAB, on the other hand, provides you with these two eigenvalue solvers:
- Subspace Iteration
- Shifted inverse power method
The selection of the eigenvalue solver depends primarily on your model size.
As soon as the program has completed the calculation, the eigenvalues, natural frequencies and periods are listed. These result windows are integrated in the main program RFEM/RSTAB. You can find all mode shapes of the structure in tables and also have an option to display them graphically and to animate them.
All result tables and graphics are part of the RFEM/RSTAB printout report. In this way, you can ensure clearly arranged documentation. You can also export the tables to MS Excel.
- Automatic generation of FE analysis models: The add-on automatically creates a finite element model (FE) of the steel connection in the background.
- Consideration of all internal forces: The calculation and design checks include all internal forces (N, Vy, Vz, My, Mz, MT) and are not limited to planar loading.
- Automatic load transfer: All load combinations are automatically transferred to the FE analysis model of the connection. The loads are transferred directly from RFEM, so manual data input is not necessary.
- Efficient modeling: The add-on saves you time when modeling complex connection situations. You can also save the created FE analysis model and use it further for your own detailed analyses.
- Extensible library: An extensive and extensible library with predefined steel connection templates is available.
- Wide applicability: The add-on is suitable for connections of any type and shape, compatible with almost all rolled, welded, built-up, and thin-walled cross-sections.
- Selection of nodes in the RFEM model, automatic recognition and assignment of the members connected to the node
- Many predefined components available for easy input of typical connection situations (for example, end plates, cleats, fin plates)
- Universally applicable basic components (plates, welds, auxiliary planes) for entering complex connection situations
- No manual editing of the FE model required by the user, the essential calculation settings can be changed via the configuration settings
- Automatic adaptation of the connection geometry, even if the members are subsequently edited, due to the relative relation of the components to each other
- Parallel to the input, a plausibility check is carried out by the program to quickly detect missing input or collisions, for example
- Graphical display of the connection geometry that is updated in parallel with the input
The program supports you: It determines the bolt forces on the basis of the FE analysis model and evaluates them automatically. The add-on performs the standard-compliant design of bolt resistance for failure cases, such as tension, shear, hole bearing, and punching, and clearly displays all required coefficients.
Do you want to perform weld design? The welds are modeled as elastic-plastic surface elements, and their stresses are read out from the FE analysis model. The plasticity criteria is set in the way that they represent failure according to AISC J2-4, J2-5 (strength of welds), and J2-2 (strength of base metal). The design can be performed with the partial safety factors of the selected National Annex of EN 1993‑1‑8.
The plates in the connection are designed plastically by comparing the existing plastic strain to the allowable plastic strain. The default setting is 5% according to EN 1993‑1‑5, Annex C, but can be adjusted by user-defined specifications, as well as 5% for AISC 360.
You can display all essential results on the FE model. In this case, you can filter the results separately according to the respective components.
Furthemore, RFEM delivers you all design checks in a tabular form, including the display of the formulas used. If you wish, you can transfer the result tables to the RFEM printout report.
- Stress determination using an elastic-plastic material model
- Design of masonry disc structures for compression and shear on the building model or single model
- Automatic determination of stiffness of a wall-slab hinge
- An extensive material database for almost all stone-mortar combinations available on the Austrian market (the product range is continuously being expanded, for other countries as well)
- Automatic determination of material values according to Eurocode 6 (ÖN EN 1996‑X)
- Option to create pushover analysis
You enter and model the structure directly in RFEM. You can combine the masonry material model with all common RFEM add-ons. This enables you to design the entire building models in connection with masonry.
The program automatically determines for you all parameters required for the calculation by using the material data that you have entered. Then, it finally generates the stress-strain curves for each FE element.
Was your design successful? Then just sit back and relax. You benefit from the numerous functions in RFEM also here. The program gives you the maximum stresses of the masonry surfaces, whereby you can display the results in detail at each FE mesh point.
Moreover, you can insert sections in order to carry out a detailed evaluation of the individual areas. Use the display of the yield areas to estimate the cracks in the masonry.
Compared to the RF‑/STABILITY (RFEM 5) and RSBUCK (RSTAB 8) add-on modules, the following new features have been added to the Structure Stability add-on for RFEM 6 / RSTAB 9:
- Activation as a property of a load case or a load combination
- Automated activation of the stability calculation via combination wizards for several load situations in one step
- Incremental load increase with user-defined termination criteria
- Modification of the mode shape normalization without recalculation
- Result tables with filter option
Compared to the RF‑/DYNAM Pro - Natural Vibrations add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Modal Analysis add-on for RFEM 6 / RSTAB 9:
- Preset combination coefficients for various standards (EC 8, ASCE, and so on)
- Optional neglect of masses (for example, mass of foundations)
- Methods for determining the number of mode shapes (user-defined, automatic - to reach effective modal mass factors, automatic - to reach the maximum natural frequency)
- Output of modal masses, effective modal masses, modal mass factors, and participation factors
- Masses in mesh points displayed in tables and graphics
- Various scaling options for mode shapes in the Result navigator
Compared to the RF‑/STEEL add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Stress-Strain Analysis add-on for RFEM 6 / RSTAB 9:
- Treatment of members, surfaces, solids, welds (line welded joints between two and three surfaces with subsequent stress design)
- Output of stresses, stress ratios, stress ranges, and strains
- Limit stress depending on the assigned material or a user-defined input
- Individual specification of the results to be calculated through freely assignable setting types
- Non-modal result details with prepared formula display and additional result display on the cross-section level of members
- Output of the design check formulas used
Compared to the RF‑/STEEL EC3 add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Steel Design add-on for RFEM 6 / RSTAB 9:
- In addition to Eurocode 3, other international standards are integrated (such as AISC 360, CSA S16, GB 50017, SP 16.13330)
- Consideration of hot-dip galvanizing (DASt guideline 027) in the fire protection design according to EN 1993‑1‑2
- Input option for transverse stiffeners that can be taken into account in the shear buckling analysis
- Lateral-torsional buckling can also be checked for hollow sections (for example, relevant for slender, high rectangular hollow sections)
- Automatic detection of members or member sets valid for the design (for example, automatic deactivation of members with invalid material or members already contained in a member set)
- Design settings can be adjusted individually for each member
- Graphical display of the results in the gross section or the effective section
- Output of the used design check formulas (including a reference to the used equation from the standard)