After the calculation, the deformations, internal forces, support forces, and stresses are displayed. Since the module considers warping torsion, the diagrams of the warping bimoment, as well as of the primary and the secondary torsional moment, are also available. Stability analysis uses the imperfections during the calculation and determines the critical load factors that can be used to determine Mki and Nki.
In addition to the result values in tables, the corresponding cross-section graphic is shown. In RFEM/RSTAB, various results are highlighted in different colors on the member model. You can modify the colors and values assigned.
Result diagrams of a set of members provide targeted evaluation. It is also possible to represent all intermediate values. Finally, it is possible to export all tables to MS Excel or in a CSV file. A dialog box includes the necessary export data.
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.
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
Geometry, material, cross-section, action, and imperfection data are entered in clearly arranged input windows:
Geometry
Quick and convenient data input
Definition of support conditions based on various support types (hinged, hinged movable, rigid, and user-defined, as well as lateral on upper or bottom flange)
Optional specification of warping restraint
Variable arrangement of rigid and deformable support stiffeners
Possibility to insert hinges
CRANEWAY Cross-Sections
I-shaped rolled cross-sections (I, IPE, IPEa, IPEo, IPEv, HE-B, HE-A, HE-AA, HL, HE-M, HE, HD, HP, IPB-S, IPB-SB, W, UB, UC, and other cross-sections according to AISC, ARBED, British Steel, Gost, TU, JIS, YB, GB, and others) combinable with section stiffener on the upper flange (angles or channels) as well as rail (SA, SF) or splice with user-defined dimensions
Unsymmetrical I-sections (type IU) also combinable with stiffeners on the upper flange as well as with rail or splice
Actions
It is possible to consider the actions of up to three simultaneously operated cranes. You can simply select a standard crane from the library. You can also enter data manually:
Number of cranes and crane axles (maximum of 20 axles per crane), center distances, position of crane buffers
Classification in damage classes with editable dynamic factors according to EN 1993-6, and in lifting classes and exposure categories according to DIN 4132
Vertical and horizontal wheel loads from self-weight, hoist load, mass forces from drive, as well as loads from skewing
Axial loading in driving direction as well as buffer forces with user-defined eccentricities
Permanent and variable secondary loads with user-defined eccentricities
Imperfections
The imperfection load applies in compliance with the first natural vibration mode - either identically for all load combinations to be designed, or individually for each load combination, as mode shapes may vary depending on the load.
Convenient tools available for scaling the mode shapes (rise determination of inclination and precamber).
The results of warping torsion analysis are displayed in RF-/STEEL AISC and RF-/STEEL EC3 in the usual way. Among other results, the corresponding result windows include the critical warping and torsional values, internal forces, and design summary.
The graphical display of mode shapes (incl. warping) enables a realistic assessment of buckling behavior.
Since RF-/STEEL Warping Torsion is fully integrated in RF-/STEEL AISC and RF‑/STEEL EC3, the data are entered in the same way as for the usual design in these modules. It is only necessary to select the option "Perform warping analysis" in the Details dialog box, tab Warping Torsion (see the figure on the right). You can also define the maximum number of iterations in this dialog box.
The warping torsion analysis is performed for sets of members in RF-/STEEL AISC and RF‑/STEEL EC3. You can define boundary conditions such as nodal supports or member end releases for them. It is also possible to specify imperfections for the nonlinear calculation.
Full integration in the RF-/STEEL EC3 add‑on module
Design of cross-sections for tension, compression, bending, torsion, shear, and combined internal forces
Plastic design of members according to the second‑order analysis with 7 degrees of freedom, including warping torsion (requires module extension RF‑/STEEL Warping Torsion).
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
Due to the integrated RF-/STEEL Warping Torsion module extension, it is possible to perform the design according to Design Guide 9 in RF-/STEEL AISC.
The calculation is performed with 7 degrees of freedom according to the warping torsion theory and enables a realistic stability design, including consideration of torsion.
Available for cold-formed L, Z, C, channel, top-hat, and CL sections from the cross-section database, as well as for general cold-formed (non-perforated) SHAPE-THIN-9 sections
Determination of the effective cross-section considering the local buckling and the distortional buckling
Cross-section ultimate limit state, stability, and serviceability limit state designs according to EN 1993‑1‑3
Design of local transverse forces for webs without stiffening
Available for all National Annexes included in RF-/STEEL EC3
Module extension RF-/STEEL Warping Torsion (license required) for stability analysis according to second-order analysis as stress analysis including consideration of the 7th degree of freedom (warping)
The number of degrees of freedom in a node is no longer a global calculation parameter in RFEM (6 degrees of freedom for each mesh node in 3D models, 7 degrees of freedom for the warping torsion analysis). Thus, each node is generally considered with a different number of degrees of freedom, which leads to a variable number of equations in the calculation.
This modification speeds up the calculation, especially for models where a significant reduction of the system could be achieved (for example, trusses and membrane structures).
Consideration of 7 local deformation directions (ux, uy, uz, φx, φy, φz, ω) or 8 internal forces (N, Vu, Vv, Mt,pri, Mt,sec, Mu, Mv, Mω) when calculating member elements
Usable in combination with a structural analysis according to linear static, second-order, and large deformation analysis (imperfections can also be taken into account)
In combination with the Stability Analysis add-on, allows you to determine critical load factors and mode shapes of stability problems such as torsional buckling and lateral-torsional buckling
Consideration of end plates and transverse stiffeners as warping springs when calculating I-sections with automatic determination and graphical display of the warping spring stiffness
Graphical display of the cross-section warping of members in the deformation
You can perform the calculation of the warping torsion on the entire system. Thus, you consider the additional 7th degree of freedom in the member calculation. The stiffnesses of the connected structural elements are automatically taken into account. It means, you don't need to define equivalent spring stiffnesses or support conditions for a detached system.
You can then use the internal forces from the calculation with warping torsion in the add-ons for the design. Consider the warping bimoment and the secondary torsional moment, depending on the material and the selected standard. A typical application is the stability analysis according to the second-order theory with imperfections in steel structures.
Did you know that The application is not limited to thin-walled steel cross-sections. Thus, it is possible for you, for example, to perform the calculation of the ideal overturning moment of beams with solid timber cross-sections.
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)