In the "Group of Imperfection Cases" imperfection case, you can enter several geometric imperfection cases. This allows you to carry out GMNIA analyses where several geometric imperfections have to be superimposed.
Have you already discovered the tabular and graphical output of masses in mesh points? That's right, this is also part of the modal analysis results in RFEM 6. This way, you can check the imported masses that depend on various settings of the modal analysis. They can be displayed in the Masses in Mesh Points tab of the Results table. The table provides you with an overview of the following results: Mass - Translational Direction (mX, mY, mZ), Mass - Rotational Direction (mφX, mφY, mφZ), and the Sum of Masses. Would it be best for you to have a graphical evaluation as quickly as possible? Then you can also graphically display the masses in mesh points.
As you've already learned, the results of a Modal Analysis load case are displayed in the program after a successful calculation. You can thus immediately see the first mode shape graphically or as an animation. You can also easily adjust the representation of the mode shape standardization. Do that directly in the Results navigator, where you have one of four options for the visualization of the mode shapes available for the selection:
Scaling the value of the mode shape vector uj to 1 (considers the translation components only)
Selecting the maximum translational component of the eigenvector and setting it to 1
Considering the entire eigenvector (including the rotation components), selecting the maximum, and setting it to 1
Setting the modal mass mi for each mode shape to 1 kg
You can find a detailed explanation of the mode shape standardization in the OnlineManual here.
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)
In RFEM, there are new useful result types available for you:
2D | XZ | 3D
2D | XY | 3D
1D | X | 3D
These model types allow you the modeling in a 1D or 2D environment (with optional cross-section rotation in all directions), but also a three-dimensional load application and resulting 3D internal forces.
Compared to the RF‑/ALUMINUM add-on module (RFEM 5 / RSTAB 8), the following new features have been added to the Aluminum Design add-on for RFEM 6 / RSTAB 9:
In addition to Eurocode 9, the US standard ADM 2020 is integrated.
Consideration of the stabilizing effect of purlins and sheets by rotational restraints and shear panels
Graphical display of the results in the gross section
Output of the used design check formulas (including a reference to the used equation from the standard)
Do you know exactly how the form-finding is performed? First, the form-finding process of the load cases with the load case category "Prestress" shifts the initial mesh geometry to an optimally balanced position by means of iterative calculation loops. For this task, the program uses the Updated Reference Strategy (URS) method by Prof. Bletzinger and Prof. Ramm. This technology is characterized by equilibrium shapes that, after the calculation, comply almost exactly with the initially specified form-finding boundary conditions (sag, force, and prestress).
In addition to the pure description of the expected forces or sags on the elements to be formed, the integral approach of the URS also enables a consideration of regular forces. In the overall process, this allows, for example, for a description of the self-weight or a pneumatic pressure by means of corresponding element loads.
All these options give the calculation kernel the potential to calculate anticlastic and synclastic forms that are in an equilibrium of forces for planar or rotationally symmetric geometries. In order to be able to realistically implement both types individually or together in one environment, the calculation provide you with two ways to describe the form-finding force vectors:
Tension method - description of the form-finding force vectors in space for planar geometries
Projection method - description of the form-finding force vectors on a projection plane with fixation of the horizontal position for conical geometries
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.
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
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)
Stability analyses for flexural buckling, torsional buckling, and flexural-torsional buckling under compression
Lateral-torsional buckling analysis of the structural components subjected to moment loading
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
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 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)
Also on the rendered model, you see your results in a clear color display. Thus, you can exactly recognize the rotation of a member or the stress distribution in a surface, for example. If you want to set the colors and value ranges, you can easily do so in the control panel.
Do you want to combine actions? Then use this feature. Here, the actions are automatically superimposed in accordance with combination expressions and then displayed as "action combinations". You can define which action combinations will eventually be used for the generation of load or result combinations. Based on the created action combinations, you can estimate how the combination expressions affect the number of combinations.
Rely on RFEM 6 even in the case of result combinations. First, you can have the contained load cases calculated in the result combinations. Then, the results are superimposed by taking into account the corresponding factors. In the result combinations, you can superimpose the results of load cases, load combinations, and other result combinations. Internal forces are added together by default. However, you have the option of a square addition, which is relevant for dynamic analysis.
In STEEL AISC, it is possible to consider lateral intermediate supports at any location. For example, it is possible to stabilize only the upper flange.
Furthermore, user-defined lateral intermediate supports can be assigned; for example, single rotational springs and translational springs at any location at the cross-section.
Import of materials, cross-sections, and internal forces from RFEM/RSTAB
Steel design of thin‑walled cross‑sections according to EN 1993‑1‑1:2005 and EN 1993‑1‑5:2006
Automatic classification of cross-sections according to EN 1993-1-1:2005 + AC:2009, Cl. 5.5.2, and EN 1993-1-5:2006, Cl. 4.4 (cross-section class 4), with optional determination of effective widths according to Annex E for stresses under fy
Integration of parameters for the following National Annexes:
DIN EN 1993-1-1/NA:2015-08 (Germany)
ÖNORM B 1993-1-1:2007-02 (Austria)
NBN EN 1993-1-1/ANB:2010-12 (Belgium)
BDS EN 1993-1-1/NA:2008 (Bulgaria)
DS/EN 1993-1-1 DK NA:2015 (Denmark)
SFS EN 1993-1-1/NA:2005 (Finland)
NF EN 1993-1-1/NA:2007-05 (France)
ELOT EN 1993-1-1 (Greece)
UNI EN 1993-1-1/NA:2008 (Italy)
LST EN 1993-1-1/NA:2009-04 (Lithuania)
UNI EN 1993-1-1/NA:2011-02 (Italy)
MS EN 1993-1-1/NA:2010 (Malaysia)
NEN EN 1993-1-1/NA:2011-12 (Netherlands)
NS EN 1993-1-1/NA:2008-02 (Norway)
PN EN 1993-1-1/NA:2006-06 (Poland)
NP EN 1993-1-1/NA:2010-03 (Portugal)
SR EN 1993-1-1/NB:2008-04 (Romania)
SS EN 1993-1-1/NA:2011-04 (Sweden)
SS EN 1993-1-1/NA:2010 (Singapore)
STN EN 1993-1-1/NA:2007-12 (Slovakia)
SIST EN 1993-1-1/A101:2006-03 (Slovenia)
UNE EN 1993-1-1/NA:2013-02 (Spain)
CSN EN 1993-1-1/NA:2007-05 (Czech Republic)
BS EN 1993-1-1/NA:2008-12 (the United Kingdom)
CYS EN 1993-1-1/NA:2009-03 (Cyprus)
In addition to the National Annexes (NA) listed above, you can also define a specific NA, applying user‑defined limit values and parameters.
Automatic calculation of all required factors for the design value of flexural buckling resistance Nb,Rd
Automatic determination of the ideal elastic critical moment Mcr for each member or set of members on every x-location according to the Eigenvalue Method or by comparing moment diagrams. You only have to define the lateral intermediate supports.
Design of tapered members, unsymmetric sections or sets of members according to the General Method as described in EN 1993-1-1, Cl. 6.3.4
In the case of the General Method according to Cl. 6.3.4, optional application of "European lateral-torsional buckling curve" according to Naumes, Strohmann, Ungermann, Sedlacek (Stahlbau 77 [2008], pp. 748‑761)
Rotational restraints can be taken into account (trapezoidal sheeting and purlins)
Optional consideration of shear panels (for example, trapezoidal sheeting and bracing)
RF-/STEEL Warping Torsion module extension (license required) for stability analysis according to the second-order analysis as stress analysis including consideration of the 7th degree of freedom (warping)
Module extension RF-/STEEL Plasticity (license required) for plastic analysis of cross‑sections according to Partial Internal Forces Method (PIFM) and Simplex Method for general cross‑sections (in connection with the RF‑/STEEL Warping Torsion module extension, it is possible to perform the plastic design according to the second‑order analysis)
Module extension RF-/STEEL Cold-Formed Sections (license required) for ultimate and serviceability limit state designs for cold-formed steel members according to the EN 1993-1-3 and EN 1993-1-5 standards
ULS design: Selection of fundamental or accidental design situations for each load case, load combination, or result combination
SLS design: Selection of characteristic, frequent, or quasi-permanent design situations for each load case, load combination, or result combination
Tension analysis with definable net cross-section areas for member start and end
Weld designs of welded cross-sections
Optional calculation of warp spring for nodal support on sets of members
Graphic of design ratios on cross-section and in RFEM/RSTAB model
Determination of governing internal forces
Filter options for graphical results in RFEM/RSTAB
Representation of design ratios and cross‑section classes in the rendered view
Color scales in result windows
Automatic cross-section optimization
Transfer of optimized cross-sections to RFEM/RSTAB
Parts lists and quantity surveying
Direct data export to MS Excel
Verifiable printout report
Possibility to include the temperature curve in the report
RF-/STEEL EC3 automatically imports the cross-sections defined in RFEM/RSTAB. It is possible to design all thin-walled cross-sections. The program automatically selects the most efficient method according to standards.
The ultimate limit state design takes into account several loads and you can select the interaction designs available in the standard.
The classification of designed cross-sections into Classes 1 to 4 is an essential part of the analysis according to Eurocode 3. This way, you can check the limitation of the design and rotational capacity by means of the local buckling of cross-section parts. RF-/STEEL EC3 determines the c/t-ratios of the cross-section parts subjected to compression stress and performs the classification automatically.
For the stability analysis, you can specify for each member or set of members whether flexural buckling occurs in the y- and/or the z-direction. You can also define additional lateral restraints in order to represent the model close to reality. The slenderness ratio and elastic critical load are determined automatically on the basis of the boundary conditions of RF-/STEEL EC3. The elastic critical moment for lateral-torsional buckling required for the lateral-torsional buckling analysis can be determined automatically or specified manually. The load application point of transverse loads, which has an influence on the torsional resistance, can also be taken into account via the setting in the details. In addition, you can take into account rotational restraints (for example trapezoidal sheeting and purlins) and shear panels (for example trapeziodal sheeting and bracing).
In modern construction, where cross-sections are increasingly slender, the serviceability limit state is an important factor in structural analysis. RF-/STEEL EC3 assigns load cases, load combinations, and result combinations to different design situations. The respective limit deformations are preset in the National Annex and can be adjusted, if necessary. In addition, it is possible to define reference lengths and precambers for the design.
The geometry is entered by means of templates, as in all other programs of the RX‑TIMBER family. By selecting the roof structure, you define the base geometry, which can be adjusted by user-defined settings. The relevant timber grade of the material can be selected from the material library. All material grades for glulam, hardwood, poplar and softwood timber specified in EN 1995-1-1 are available. Furthermore, it is possible to generate a strength class with user-defined material properties in order to extend the library.
Since the stiffening bracing includes the steel cross-sections, current steel grades are integrated in the library as well. Therefore, rolled and welded cross-sections are also available. Stiffening of coupling elements can be considered in Table 1.5 Connections as translational and rotational spring stiffnesses. The program handles these stiffnesses with a stiffness divided by the partial safety factor for the design of the bearing capacity and with the mean values of the stiffness for the serviceability limit state design. The loading can be entered directly as a lateral load (equivalent lateral load) resulting from a truss girder design.
The wind load is applied automatically to all four sides of the structure. Additionally, you can specify user-defined loads; for example, concentrated loads from columns (buckling load). According to the generated loads, the program automatically creates combinations for the ultimate and serviceability limit states as well as for fire resistance design in the background. The generated combinations can be considered or adjusted by user-defined specifications.
There are various options available for modeling a roof. Graphical representations facilitate the geometry input. Modifications are updated automatically.
In addition, it is possible to consider cross‑section weakening on supports. Optionally, you can define if the design of support pressure on the rafter side should be performed.
Permanent loads (for example, roof structure) can be entered using the comprehensive and extensible material library. Loads due to cantilevers and collars/ties can be entered separately. Generators integrated in RX-TIMBER Purlin allow for convenient generation of various wind and snow load cases. You can manually add any concentrated and distributed loads.
Load cases are displayed graphically and superimposed in automatically generated load combinations according to EC 5. For stability and serviceability limit state designs, you can change the data manually, for example, for example, for cantilevers (roof overhang), it is necessary to ignore the SLS.
Definition of any additional support and free selection of degrees of freedom (additional free definition of translational and rotational spring stiffness of supports and hinges)
Arrangement of up to five collar/tie beams, including intermediate support for duopitch roof
Automatic generation of wind and snow loads
Automatic generation of required combinations for the ultimate and serviceability limit states, as well as fire resistance design (additional definition of several member and nodal loads)
For design according to EC 5 (EN 1995), the following National Annexes are available:
Germany DIN EN 1995-1-1/NA:2013-08 (Germany)
NBN EN 1995-1-1/ANB:2012-07 (Belgium)
BDS EN 1995-1-1/NA:2012-02 (Bulgaria)
DK EN 1995-1-1/NA:2011-12 (Denmark)
SFS EN 1995-1-1/NA:2007-11 (Finland)
NF EN 1995-1-1/NA:2010-05 (France)
I S. EN 1995-1-1/NA:2010-03 (Ireland)
UNI EN 1995-1-1/NA:2010-09 (Italy)
NEN EN 1995-1-1/NB:2007-11 (Netherlands)
ÖNORM B 1995-1-1:2015-06 (Austria)
PN EN 1995-1-1/NA:2010-09 (Poland)
SS EN 1995-1-1 (Sweden)
STN EN 1995-1-1/NA:2008-12 (Slovakia)
SIST EN 1995-1-1/A101:2006-03 (Slovenia)
CSN EN 1995-1-1:2007-09 (Czech Republic)
BS EN 1995-1-1/NA:2009-10 (the United Kingdom)
CYS EN 1995-1-1/NA:2011-02 (Cyprus)
Simple geometry input with illustrative graphics
Input of tapered cantilevers with cut-to-grain on the bottom side of rafters
Extensive material library that can be extended by user-defined materials
Determination of design ratios, support forces, and deformations
Color reference scales in result tables
Direct data export to MS Excel
Program languages: English, German, Czech, Italian, Spanish, French, Portuguese, Polish, Chinese, Dutch, and Russian
Verifiable printout report, including all required designs. Printout report available in many output languages; for example, English, German, French, Italian, Spanish, Russian, Czech, Polish, Portuguese, Chinese, and Dutch.
The results on a rendered model are represented by a number of colors in order to easily detect deformations such as member rotation. You can freely define the colors and the range of values in the control panel. Deformations, surface stresses, and internal forces can be animated and saved as a video file.
The load cases included in the result combinations are calculated first. Then, the results are superimposed by taking into account the corresponding factors. In the result combinations, you can superimpose the results of load cases, load combinations, and other result combinations. Internal forces are added together by default. However, there is the option of a square addition, which is relevant for dynamic analysis.
The actions are automatically superimposed in accordance with combination expressions and then displayed as "action combinations". It is possible to define which action combinations will eventually be used for the generation of load or result combinations. Based on the created action combinations, you can estimate how the combination expressions affect the number of combinations.
The results on a rendered model are represented by a number of colors in order to easily detect deformations such as member rotation. You can freely define the colors and the range of values in the control panel. Deformation diagrams can be animated and saved as a video file.
Comprehensive and easy options in the individual input windows facilitate the representation of the structural system:
Nodal Supports
The support type of each node is editable.
It is possible to define a warp stiffening on each node. The resulting warp spring is determined automatically using the input parameters.
Elastic member foundation
In the case of elastic member foundations, you can manually enter spring constants.
Alternatively, you can use the various options to define the rotational and translational springs from a shear panel.
Member End Springs
RF-/FE-LTB calculates the individual spring constants automatically. You can use the dialog boxes and detailed pictures to represent a translational spring by connecting component, a rotational spring by a connecting column, or a warping stiffener (available types: end plate, channel section, angle, connecting column, cantilevered portion).
Member Hinges
If there are no member hinges defined in RFEM/RSTAB for the set of members, you can define them directly in the RF-/FE-LTB add-on module.
Load Data
The nodal and member loads of the selected load cases and combinations are displayed in separate windows. There you can edit, delete, or add them individually.
Imperfections
RF-/FE-LTB automatically applies the imperfections by scaling the lowest eigenvector.
In RF‑/LTB, the design is usually performed according to the equivalent member method according to DIN 18800, Part 2. However, you can specify extensive detailed settings for the design in a separate dialog box:
Design according to Bird/Heil
Optionally, it is possible to apply the method according to Bird/Heil in the program
the required shear stiffness Sreq
the lateral-torsional buckling load Nki
the critical buckling moment Mki
.
This plastic-plastic calculation method is only valid for lateral and torsional restraints with simple bending with simultaneous load introduction on the upper flange. Further requirements that must be met can be found in the program manual. In case of invalid conditions (for example, biaxial bending), RF-/LTB displays the corresponding error message. In addition, the reduction factorκM for the bending moments My can be set to 1.0 if a restrained rotation axis is present.
Non-Designable Internal Forces
It is possible to neglect non-designable internal forces and thus exclude them from the design if the quotient of the internal force and the fully plastic internal force falls below a certain value. This way, you can neglect, for example, a small moment about the minor axis, thus avoiding the method for biaxial bending.
Allowance according to DIN 18800, Part 2, Element (320) and Element (323)
Automatic determination of ζ
If you want the factor for the determination of the ideal elastic critical moment Mcr to be determined automatically, you can select one of the following types:
Solving the elastic potential numerically
Comparison of moment diagrams
Australian Standard AS 4100-1990
US standard AISC LRFD
When aligning the moment distributions, you can use the library which contains more than 600 moment distributions in tables.
The details for the lateral-torsional buckling analysis are defined separately for members and sets of members. The following parameters can be set:
Support Type/Lateral-Torsional Buckling Load
Available options are Lateral and torsional restraint, Lateral and torsional restraint or Cantilever
Special supports are possible by specifying the degree of restraint βz and the degree of warping restraint β0. In this section as well, you can consider the elastic warping restraint of an end plate, a channel section, an angle, a column connection, and a beam cantilever by specifying the geometry dimensions.
As an alternative, it is also possible to enter the lateral-torsional buckling load NKi or the effective length sKi directly
Shear panel
A shear panel can be defined from a trapezoidal sheeting, bracing, or a combination of these
Alternatively, you can enter the shear panel stiffness Sprov directly
Rotational restraint
Choose between continuous and discontinuous rotational restraint
Position of Positive Transverse Load Application
The z-coordinate of the load application point can be freely selected in a detailed cross-section graphic. (upper chord, lower chord, centroid)
Alternatively, you can specify the data by selecting them or entering the data manually.
Beam Type
For standard sections, the rolled beam, welded beam, castellated beam, notched beam, or tapered beam (web or flange welded) options are available
For special cross-sections, it is possible to directly enter the beam factor n, the reduced beam factor n, or the reduction factor κM
Integration in RFEM/RSTAB with automatic geometry recognition and transfer of internal forces
Optional manual definition of connections
Extensive library of hollow sections for chords and struts:
Round sections
Square sections
Rectangular sections
Implemented steel grades: S 235, S 275, S 355, S 420, S 450, and S 460
Various types of connections available, depending on the standard specifications:
K connection (gap/overlapping)
KK connection (spatial)
N connection (gap/overlapping)
KT connection (gap/overlapping)
DK connection (gap/overlapping)
T connection (planar)
TT connection (spatial)
Y connection (planar)
X connection (planar)
XX connection (spatial)
Selection of partial safety factors according to the National Annex for Germany, Austria, Czech Republic, Slovakia, Poland, Slovenia, Switzerland, or Denmark
Adjustable angles between struts and chords
Optional chord rotation of 90° for rectangular hollow sections
Consideration of gaps between struts or overlapping struts
Optional consideration of additional nodal forces
Design of the connection as the maximum load-bearing capacity of the struts of a truss for axial forces and bending moments