Question
I am designing a cross-section created in the SHAPE‑THIN program using the design add-on module, but the program shows the error message "ER006 Invalid type of c/t-part for cross-section of type General". What can I do?
Answer:
In the SHAPE‑THIN stand-alone program, it is not possible to calculate the c/t-field for rounded elements entered in the cross-section. If you replace all arc parts in this cross-section, calculate the cross-section, save it, and import it into RFEM again, the design will be possible.
Do you have any questions?
![Warping Restraint via End Plate](/en/webimage/010484/2978100/1_warping_restraint_from_end_plate.png?mw=512&hash=b43e17cbb11faa3b51820d5bc88f6c5f2d58db81)
In the case of open cross-sections, the torsional load is removed mainly via secondary torsion, since the St. Venant torsional stiffness is low compared to the warping stiffness. Therefore, warping stiffeners in the cross-section are particularly interesting for the lateral-torsional buckling analysis, as they can significantly reduce the rotation. For this, end plates or welded stiffeners and sections are suitable.
![Entering Intermediate Lateral Restraint in Center of Member 1](/en/webimage/010537/2968407/1_Intermediate_lateral_restraint_in_the_middle_of_beam_1.png?mw=512&hash=b59e15e6f9f5b251a280addda3968092369a2f14)
The support conditions of a beam subjected to bending are essential for its resistance to lateral-torsional buckling. If, for example, a single-span beam is held laterally in the middle of the span, the deflection of the compressed flange can be prevented, and a two-wave eigenmode can be enforced. The critical lateral-torsional buckling moment is increased significantly by this additional measure. In the add-on modules for member design, different types of lateral supports on a member can be defined using the "Intermediate supports" input window.
![KB 001883 | Plate Girder Design According to AISC 360-22 in RFEM 6](/en/webimage/051561/3980997/im1.png?mw=512&hash=b8237709c4f30213fac51d86d32a42bddde72f03)
Plate girder is an economical choice for long spans construction. I-section steel plate girder typically has a deep web to maximize its shear capacity and flange separation, yet thin web to minimize the self-weight. Due to its large height-to-thickness (h/tw) ratio, transverse stiffeners may be required to stiffen the slender web.
![Steel Connection Rigidity and Its Influence on Structural Design](/en/webimage/051432/3972404/Rigidity-caseA.png?mw=512&hash=3be64e68ab2956fd2b92f0afa1559b3a8c72b468)
Understanding steel connection rigidity is crucial in structural design. Often, connections are treated as strictly pinned or rigid, but this can lead to uneconomical or even dangerous designs. Explore how Dlubal Software's RFEM and Steel Joints add-on help verify connection stiffness and moment resistance, ensuring safer and more economical designs.
![Add-on "Steel Joints for RFEM 6" | Component Library](/en/webimage/043097/3898884/steel_joints_components.png?mw=512&hash=e4f835906155863fc7019d5043b22e553dc766f9)
- Numerous component types, such as base and end plates, web angles, fin plates, gusset plates, stiffeners, tapers, or ribs for easy input of typical connection situations
- Universally applicable basic components (such as plates, welds, bolts, auxiliary planes) for modeling complex connection situations
- Graphical display of the connection geometry with dynamic updating during the input
- Wide range of cross-section shapes: I-sections, U-sections, angles, T-sections, hollow sections, built-up cross-sections and thin-walled sections
- Library in the Dlubal Center with a large number of program-side template connections, including user-defined templates
- Automatic adaptation of the connection geometry based on the relative arrangement of the components to each other – even in case of subsequent editing of the structural components
![Feature 002820 | Limit Plastic Strain for Welds](/en/webimage/050344/3881226/1.png?mw=512&hash=9d7f6c198b6d4ae6ee8f2fa8bca75f85579e14c9)
In the ultimate configuration of the steel joint design, you have the option to modify the limit plastic strain for welds.
![Component "Base Plate"](/en/webimage/050345/3936120/50345.png?mw=512&hash=3bd641cb1a2445804b338855e4debfc40c6563e9)
The "Base Plate" component allows you to design base plate connections with cast-in anchors. In this case, plates, welds, anchorages, and steel-concrete interaction are analyzed.
![Feature 002807 | 3D Display of FSM Results](/en/webimage/049281/3861162/2024-05-01_10-32-55.png?mw=512&hash=2377d291bc20ac3d78d617b50c131614e99ac6f7)
In the "Edit Section" dialog box, you can display the buckling shapes of the Finite Strip Method (FSM) as a 3D graphic.
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