The Steel Joints add-on provides you with the option to connect circular hollow sections using welds.
It is possible to connect the circular sections to each other or to planar structural components. The fillets of standard and thin-walled sections can also be connected with a weld.
In the Steel Joints add-on, you can classify the joint stiffness.
In addition to the initial stiffness, the table also shows the limit values for hinged and rigid connections for the selected internal forces N, My, and/or Mz. The resulting classification is then displayed in tables as "hinged", "semi-rigid", or "rigid".
In the "Steel Joints" add-on, you can consider preloaded bolts in all components during the calculation. You can easily activate the preloading using the check box in the bolt parameters, and it has an impact on the stress-strain analysis as well as the stiffness analysis.
Preloaded bolts are special bolts used in steel structures to generate a high clamping force between the connected structural components. This clamping force causes friction between the structural components, which allows for the transfer of forces.
Functionality Preloaded bolts are tightened with a certain torque, causing them to stretch and generate a tensile force. This tensile force is transferred to the connected components and leads to a high clamping force. The clamping force prevents the connection from loosening and ensures safe force transmission.
Advantages
High load-bearing capacity: Preloaded bolts can transfer large forces.
Low deformation: They minimize the deformation of the connection.
Fatigue strength: They are resistant to fatigue.
Easy assembly: They are relatively easy to assemble and disassemble.
Analysis and Design The calculation of preloaded bolts is performed in RFEM using the FE analysis model generated by the "Steel Joints" add-on. It takes into account the clamping force, friction between structural components, shear strength of bolts, and load-bearing capacity of the structural components. The design is carried out according to DIN EN 1993‑1‑8 (Eurocode 3) or the US standard ANSI/AISC 360‑16. You can save the created analysis model, including the results, and use it as an independent RFEM model.
The initial stiffness Sj,ini is a crucial parameter for evaluating whether a connection can be characterized as rigid, semi-rigid, or pinned.
In the "Steel Joints" add-on, you can calculate the initial stiffness Sj,ini according to Eurocode (EN 1993‑1‑8, Section 5.2.2) and AISC (AISC 360-16, Cl. E3.4) with regard to the internal forces N, My, and/or Mz.
The optional automatic transfer of initial stiffnesses allows for a directly transfer as member hinge stiffnesses in RFEM. The entire structure is then recalculated and the resulting internal forces are automatically adopted as loads in the analysis and design of the connection models.
This automated iteration process eliminates the need for manual export and import of data, reducing the amount of work and minimizing potential sources of error.
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.
In the Steel Joint add-on, you can design the connections of members with composite cross-sections. Furthermore, you can perform joint design checks for almost all thin-walled cross-sections in the RFEM library.
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:
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.
At first, the governing joint designs are arranged in groups and displayed with the basic geometry of the joint in the first result window. In the other result windows, you can see all fundamental design details.
Dimensions, material properties, and welds important for the connection construction are displayed immediately and can be printed directly. Similarly, export to DXF-file is enabled. The connections can be visualized in the RF-/JOINTS Timber - Timber to Timber module as well as in RFEM/RSTAB.
All graphics can be included in the RFEM/RSTAB printout report or printed directly. Due to the scaled output, an optimal visual check is possible as early as in the design phase.
First, select the joint type and the design standard.
The connected members are imported from the RFEM/RSTAB model. The add-on module automatically checks if all geometry conditions are fulfilled.
In addition, the loads are imported automatically from RFEM/RSTAB. In the Geometry window, you can specify the screw parameters (diameter, length, angle, and so on).
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.