In the Modal Analysis add-on, you have the option to automatically increase the sought eigenvalues until reaching a defined effective modal mass factor. All translational directions activated as masses for the modal analysis are taken into account.
Thus, it is possible to easily calculate the required 90% of the effective modal mass for the response spectrum method.
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 Concrete Design add-on provides you with the option to perform the simplified fire resistance design according to EN 1992‑1‑2 for columns (Section 5.3.2) and beams (Section 5.6).
The following design checks are available for the simplified fire resistance design:
Columns: Minimum cross-sectional dimensions for rectangular and circular sections according to Table 5.2a as well as Equation 5.7 for calculating time of fire exposure
Beams: Minimum dimensions and center distances according to Table 5.5 and Table 5.6
You can determine the internal forces for the fire resistance design according to two methods.
1 Here, the internal forces of the accidental design situation are included directly into the design.
2 The internal forces of the design at normal temperature are reduced by the factor Eta,fi (ηfi), then used in the fire resistance design.
Furthermore, it is possible to modify the axis distance according to Eq. 5.5.
The Concrete Design add-on allows you to perform the seismic design of reinforced concrete members according to EC 8. This includes, among other things, the following functionalities:
Seismic design configurations
Differentiation of the ductility classes DCL, DCM, DCH
Option to transfer the behavior factor from a dynamic analysis
Check of the limit value for the behavior factor
Capacity design checks of "Strong column - weak beam"
Detailing and particular rules for curvature ductility factor
Detailing and particular rules for local ductility
In the Steel Joints add-on, you can design connections according to the American standard ANSI/AISC 360‑16. The following design procedures are integrated:
For timber surfaces with the "Constant" thickness type, the crack factor kcr and thus the negative influence of cracks on the shear capacity is taken into account.
Did you use the eigenvalue solver of the add-on to determine the critical load factor within the stability analysis? In this case, you can then display the governing mode shape of the object to be designed as a result.
Note that the definition of the effective lengths in the Aluminum Design add-on is an essential requirement for the stability analysis. For this, define the nodal supports and effective length factors in the input dialog box. Do you want to clearly document the nodal supports and the resulting segments with the associated effective length factors? To check the input data, it is best for you to use the graphic display in the RFEM/RSTAB work window. Thus, you can comprehend the design at any time with minimum effort.
Is the calculation finished? The results of the modal analysis are then available both graphically and in tables. Display the result tables for the load case or the load cases of the modal analysis. Thus, you can see the eigenvalues, angular frequencies, natural frequencies, and natural periods of the structure at first glance. The effective modal masses, modal mass factors, and participation factors are also clearly displayed.
A wide range of cross-sections, such as rectangular sections, square sections, T‑sections, circular sections, built-up cross-sections, irregular parametric cross-sections, and many others (suitability for design depends on the selected standard)
Design of cross-laminated timber (CLT)
Design of timber-based materials and laminated veneer lumber according to EC 5
Design of tapered and curved members (design method according to 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
Consideration of a notch
Design of compression perpendicular to the grain on the end and intermediate supports with (EC 5) and without reinforcement elements (fully threaded screws)
Optional shear force reduction at the support (see the Product Feature)
Design of curved and tapered members
Consideration of higher strengths for similar components that are close together (factor ksys according to EN 1995‑1‑1, 6.6(1)-(3))
Option to increase shear resistance for softwood timber according to DIN EN 1995‑1‑1:NA NDP to 6.1.7(2)
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
Determination of the equivalent member lengths for tapered members
Consideration of Lateral-Torsional Bracing Position
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)
As you probably know, the design checks for the selected members are carried out, taking into account the defined charring time. All necessary reduction factors and coefficients are stored accordingly in the program and are taken into account when determining the load-bearing capacity. That saves you a lot of work.
The effective lengths for the equivalent member design are taken directly from the strength entries. You do not have to enter them again.
After completing the design, the program presents the fire resistance design checks clearly and with all result details. This allows you to follow the results completely transparently. The results also contain all the required parameters, so you can determine the component temperature at the design time.
In addition to all these features, the program allows you to integrate all result tables and graphics, including the ultimate and serviceability limit state results,into the global printout report of RFEM/RSTAB as a part of the steel design results.
Here you have a free choice. You can perform the support pressure design at any point for the loading in the y- and z-directions of a cross-section. You are free to differentiate between inner and outer supports. A factor kc,90 for the pressure perpendicular to the grain can be user-defined (for example, 1.75 for glued-laminated timber). If allowed, the support length is increased automatically according to the standard specifications. This allows you to achieve a more efficient design with minimum effort.
Did you use the eigenvalue solver of the add-on to determine the critical load factor within the stability analysis? If so, you can then display the governing mode shape of the object to be designed as a result. The eigenvalue solver is available here for the lateral-torsional buckling analysis, depending on the design standard used.
The design checks for the members you have selected are carried out taking into account the governing component temperature. You can perform the cross-section design checks and stability analyses according to EN 1993‑1‑2, Section 4.2.3, in the Steel Design add-on. All reduction factors and coefficients that are necessary are stored accordingly and are taken into account when determining the load-bearing capacity.
The effective lengths for the equivalent member design are taken directly from the strength entries. You don't need to enter them again.
In each design, perform the cross-section classification first. For the cross-sections of Class 4, the design is performed automatically according to EN 1993‑1‑2, Annex E.
Do you want to perform a stability analysis in the Steel Design add-on? Then it is absolutely necessary to define the effective lengths. To do this, define the nodal supports and effective length factors in the input dialog box. For easy documentation and a comprehensible check of the entries, you can also graphically display the nodal supports and the resulting segments with the corresponding effective length factor in the work window of RFEM/RSTAB.
Did you use the eigenvalue solver of the add-on to determine the critical load factor for the stability analysis? Verz well, you can then display the governing mode shape of the object to be designed as a result. The eigenvalue solver is available for the lateral-torsional buckling analysis, depending on the design standard used. You can also use the internal eigenvalue solver for the general method according to EN 1993‑1‑1, 6.3.4.
In this case, you calculate the critical load factor for all analyzed load combinations and the selected number of mode shapes for the connection model. Compare the smallest critical load factor with the limit value 15 from the standard EN 1993‑1‑1, Clause 5. Furthermore, you can make user-defined adjustment of the limit value. As a result of the stability analysis, the program displays the corresponding mode shapes graphically.
For the stability analysis, RFEM uses the adapted surface model to specifically recognize the local buckling shapes. You can also save and use the model of the stability analysis, including the results, as a separate model file.
You can be sure that costs are an important factor in the structural planning of any project. It is also essential to adhere to the provisions on emissions estimation. The two-part add-on Optimization & Costs/CO2 Emission Estimation makes it easier for you to find your way through the jungle of standards and options. It uses the artificial intelligence technology (AI) of the particle swarm optimization (PSO) to find the right parameters for parameterized models and blocks that guarantee the compliance with the usual optimization criteria. This add-on also estimates the model costs or CO2 emissions by specifying unit costs or emissions per material definition for the structural model. With this add-on, you are on the safe side.
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
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.
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.
The program does a lot of work for you. The members to be designed are directly imported from RFEM/RSTAB.
You can easily define constructional properties of columns as well as other details for determining the required longitudinal and shear reinforcement. In this case, you can manually define the effective length factor ß or import it from the Structure Stability add-on.
Import of relevant information and results from RFEM
Integrated, editable material and section library
Sensible and complete presetting of input parameters
Punching design on columns (all section shapes), wall ends, and wall corners
Automatic recognition of the punching node position from an RFEM model
Detection of curves or splines as a boundary of the control perimeter
Automatic consideration of all slab openings defined in the RFEM model
Construction and graphical display of the control perimeter
Optional design with unsmoothed shear stress along the control perimeter that corresponds to the actual shear stress distribution in the FE model
Determination of the load increment factor β via full-plastic shear distribution as constant factors according to EN 1992‑1‑1, Sect. 6.4.3 (3), based on EN 1992‑1‑1, Fig. 6.21N, or by a user‑defined specification
Numerical and graphical display of results (3D, 2D, and in sections)
Punching design of the slab without punching reinforcement
Qualitative determination of the required punching reinforcement
Design and analysis of the longitudinal reinforcement
Complete integration of results in an RFEM printout report
RFEM supports you and save you a lot of work. The materials and surface thicknesses defined in RFEM are already preset in the Concrete Design add-on. Thus, you can directly define the nodes to be designed.
Any openings in the area with risk of punching shear are automatically taken into account in the RFEM model. The add-on recognizes the position of the nodes of punching shear and automatically determines whether it is a node of punching shear in the center of the slab, on the edge of the slab, or in a slab corner. Again, you save your time.
You can individually select the method for determining the load increment factor β.
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