The design of cold-formed steel members according to the AISI S100-16 / CSA S136-16 is available in RFEM 6. Design can be accessed by selecting “AISC 360” or “CSA S16” as the standard in the Steel Design Add-on. “AISI S100” or “CSA S136” is then automatically selected for the cold-formed design.
RFEM applies the Direct Strength Method (DSM) to calculate the elastic buckling load of the member. The Direct Strength Method offers two types of solutions, numerical (Finite Strip Method) and analytical (Specification). The FSM signature curve and buckling shapes can be viewed under Sections.
- 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
- Full integration with RFEM and RSTAB
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.
- You can activate or deactivate the use of torsional warping in the Add-ons tab of the model's Base Data.
- After activating the add-on, the user interface in RFEM is extended by some new entries in the navigator, tables, and dialog boxes.
- Modeling of the cross-section via elements, sections, arcs, and point elements
- Expansible library of material properties, yield strengths, and limit stresses
- Section properties of open, closed, or non-connected cross-sections
- Ideal section properties of cross-sections consisting of different materials
- Determination of weld stresses in fillet welds
- Stress analysis including design of primary and secondary torsion
- Check of c/t-ratios
- Effective cross-sections according to
- EN 1993-1-5 (including stiffened buckling panels according to Section 4.5)
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EN 1993-1-3
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EN 1999-1-1
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to DIN 18800-2
- Classification according to
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EN 1993-1-1
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EN 1999-1-1
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- Interface with MS Excel to import and export tables
- Printout report
- Applicable for members defined as sets of members
- Separate solver that considers 7 deformation directions (ux, uy, uz, φx, φy, φz, ω) or 8 internal forces (N, Vu, Vv, Mt,pri, Mt,sec, Mu, Mv, Mω)
- Nonlinear design according to second-order analysis
- Input of imperfections
- Calculation of critical load factors and buckling mode shapes as well as the visualization of them (incl. warping)
- Integration into member design in the RF-/STEEL AISC and RF‑/STEEL EC3 add‑on modules
- Available for all thin‑walled steel cross‑sections
All results can be evaluated and visualized in an appealing numerical and graphical form. Selection functions facilitate the targeted evaluation.
The printout report corresponds to the high standards of RFEM and rstab/rstab-9/what-is-rstab RSTAB. Modifications are updated automatically.
SHAPE-THIN calculates all relevant cross‑section properties, including plastic limit internal forces. Overlapping areas are set close to reality. If cross-sections consist of different materials, SHAPE‑THIN determines the effective cross‑section properties with respect to the reference material.
In addition to the elastic stress analysis, you can perform the plastic design including interaction of internal forces for any cross‑section shape. The plastic interaction design is carried out according to the Simplex Method. You can select the yield hypothesis according to Tresca or von Mises.
SHAPE-THIN performs a cross-section classification according to EN 1993-1-1 and EN 1999-1-1. For steel cross-sections of cross-section class 4, the program determines effective widths for unstiffened or stiffened buckling panels according to EN 1993-1-1 and EN 1993-1-5. For aluminum cross-sections of cross-section class 4, the program calculates effective thicknesses according to EN 1999-1-1.
Optionally, SHAPE‑THIN checks the limit c/t-values in compliance with the design methods el‑el, el‑pl, or pl‑pl according to DIN 18800. The c/t-zones of elements connected in the same direction are recognized automatically.
SHAPE-THIN includes an extensive library of rolled and parameterized cross-sections. They can be composed or supplemented by new elements. It is possible to model a section consisting of different materials.
Graphical tools and functions allow for modeling complex section shapes in the usual way common for CAD programs. The graphical entry provides the option of setting point elements, fillet welds, arcs, parameterized rectangular and circular sections, ellipses, elliptical arcs, parabolas, hyperbolas, spline, and NURBS. Alternatively, it is possible to import a DXF file that is used as the basis for further modeling. You can also use guidelines for modeling.
Furthermore, parameterized input allows you to enter model and load data in a specific way so they depend on certain variables.
Elements can be divided or attached to other objects graphically. SHAPE-THIN automatically divides the elements and provides for an uninterrupted shear flow by introducing dummy elements. In the case of dummy elements, you can define a specific thickness to control the shear transfer.
SHAPE-THIN determines the section properties and stresses of any open, closed, built-up, or non-connected cross-sections.
- Section Properties
- Cross-sectional area A
- Shear areas Ay, Az, Au, and Av
- Centroid position yS, zS
- moments of area 2 degrees Iy, Iz, Iyz, Iu, Iv, Ip, Ip,M
- Radii of gyration iy, iz, iyz, iu, iv, ip, ip,M
- Inclination of principal axes α
- Cross-section weight G
- Cross-section perimeter U
- torsional constants of area degrees IT, IT,St.Venant, IT,Bredt, IT,s
- Location of the shear center yM, zM
- Warping constants Iω,S, Iω,M or Iω,D for lateral restraint
- Max/min section moduli Sy, Sz, Su, Sv, Sω,M with locations
- Section ranges ru, rv, rM,u, rM,v
- Reduction factor λM
- Plastic Cross-Section Properties
- Axial force Npl,d
- Shear forces Vpl,y,d, Vpl,z,d, Vpl,u,d, Vpl,v,d
- Bending moments Mpl,y,d, Mpl,z,d, Mpl,u,d, Mpl,v,d
- Section moduli Zy, Zz, Zu, Zv
- Shear areas Apl,y, Apl,z, Apl,u, Apl,v
- Position of area bisecting axes fu, fv,
- Display of the inertia ellipse
- First moments of area Qu, Qv, Qy, Qz with location of maxima and specification of shear flow
- Warping coordinates ωM
- moments of area (warping areas) Sω,M
- Cell areas Am of closed cross-sections
- Normal stresses σx due to axial force, bending moments, and warping bimoment
- Shear stresses τ from shear forces as well as primary and secondary torsional moments
- Equivalent stresses σv with customizable factor for shear stresses
- Stress ratios, related to limit stresses
- Stresses for element edges or center lines
- Weld stresses in fillet welds
- Section properties of non-connected cross-sections (cores of high-rise buildings, composite sections)
- Shear wall shear forces due to bending and torsion
- Plastic capacity design with determination of the enlargement factor αpl
- Check of the c/t-ratios following the design methods el-el, el-pl or pl-pl according to DIN 18800
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.
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.