Automatic generation of FE analysis models: The add-on automatically creates a finite element model (FE) of the steel connection in the background.
Consideration of all internal forces: The calculation and design checks include all internal forces (N, Vy, Vz, My, Mz, MT) and are not limited to planar loading.
Automatic load transfer: All load combinations are automatically transferred to the FE analysis model of the connection. The loads are transferred directly from RFEM, so manual data input is not necessary.
Efficient modeling: The add-on saves you time when modeling complex connection situations. You can also save the created FE analysis model and use it further for your own detailed analyses.
Extensible library: An extensive and extensible library with predefined steel connection templates is available.
Wide applicability: The add-on is suitable for connections of any type and shape, compatible with almost all rolled, welded, built-up, and thin-walled cross-sections.
First, the governing design checks of the connection for the respective load case, and load combination, or result combination are displayed. In addition, it is possible to display results separately for sets of members, surfaces, cross-section, members, nodes, and nodal supports.
You can use a filter to further reduce the displayed results and thus present them in a clearer way.
Design of member ends, members, nodal supports, nodes, and surfaces
Consideration of specified design areas
Check of cross-section dimensions
Design according to EN 1995-1-1 (European Timber Standard) with the respective National Annexes + DIN 1052 + DSTV DIN EN 1993-1-8 + ANSI / AWC - NDS 2015 (US Standard)
Design of various materials, such as steel, concrete, and others
No necessary linking to specific standards
Extensible library including timber fasteners (SIHGA, Sherpa, WÜRTH, Simpson StrongTie, KNAPP, PITZL) and steel fasteners (standardized connections in steel building design according to EC 3, M-connect, PFEIFER, TG-Technik)
Ultimate load capacities of timber beams by the companies STEICO and Metsä Wood available in the library
Connection to MS Excel
Optimization of connecting elements (the most utilized element is calculated)
Design of moment resistant and simple joints of I-shaped rolled cross-sections according to Eurocode 3:
Moment-resisting end plate connections (type IH/IM)
Moment resistant purlin splices (PM type)
Simple joints with angle cleat and long angles (IW and IG types)
Simple joints with header end plates mounted either on web only or on web and flange (IS type)
Check of coped connections (IK) in combination with pinned end plates (IS) and angle connections (IW)
Automatic design of required joint with bolt sizes (all types)
Check of required thickness of load-bearing members for shear connections
Results of all required structural details such as appliances, hole arrangements, necessary extensions, a number of bolts, end plate dimensions, and welds
Results including stiffnesses Sj,ini of bending-resistant connections
Documentation of available loading and comparison with resistances
Results of design ratio for each individual joint
Automatic determination of governing internal forces for several load cases and connection nodes
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
The result windows list all results of the calculation in detail. In addition, 3D graphics are created, where individual components as well as dimension lines and, for example, This allows you, for example, to display or hide the weld data. The summary shows if the individual designs have been fulfilled: The design ratio is additionally visualized with a green data bar, which turns red when the design is not fulfilled. Furthermore, the node number and the governing LC/CO/RC are displayed.
When selecting a design, the module shows the detailed intermediate results including the actions and the additional internal forces from the connection geometry. There is the option to display the results by load case and by node. The connections are represented in a realistic 3D rendering possible to scale. In addition to the main views, it is possible to show the graphics from any perspective.
You can add the graphics with dimensions and labels to the RFEM/RSTAB printout or export them as DXF. The printout report includes all input and result data prepared for test engineers. It is possible to export all tables to MS Excel or in a CSV file. A special transfer menu defines all specifications required for the export.
After opening the add-on module, it is necessary to select the joint type (moment resistant or pinned I-beam connection). You can select the individual nodes graphically in the RFEM/RSTAB model.
The RF-/JOINTS Steel - DSTV add-on module recognizes the cross-section including the corresponding material automatically, and checks if a joint design according to the DSTV guideline is possible. Furthermore, you can model and design structurally similar connections on several locations in the beam structure.
After selecting the loads required for the design and, if necessary, the desired standard for the design, you can define the limit loads in Window 1.2 Limit Parameters. In addition to the manufacturers listed in the limit library, it is possible to add user-defined entries.
After selecting all limit elements for the design, you can optionally define the load duration class (LDC). However, this module window is available only for timber fastener design according to EN 1995-1-1 or DIN 1052.
No manual editing of the FE model required by the user, the essential calculation settings can be changed via the configuration settings
Automatic adaptation of the connection geometry, even if the members are subsequently edited, due to the relative relation of the components to each other
Parallel to the input, a plausibility check is carried out by the program to quickly detect missing input or collisions, for example
Graphical display of the connection geometry that is updated in parallel with the input
After you have selected the joint type, the connection category, and the design standard in the first input window, you can define the node to be imported from RFEM/RSTAB and to be used for the design of the joint in Window 1.2. Optionally, you can define the connection geometry manually.
In the other input windows, you can then define the parameters of the connection, such as The loading is imported from RFEM/RSTAB or, in the case of manual joint definition, loads are entered.
The design includes detailed information about analyzed internal forces, validity limits, and design conditions. Design failures are clearly marked in the result overview.
All input and result data are also documented in the general RFEM/RSTAB printout report. Separate design cases allow flexible analysis of the individual components in large structures.
First, the module combines governing designs of the column and the horizontal beam and displays the connection geometry in a result table. The other result tables include all important design details such as flow line lengths, load-bearing capacity of screws, weld stresses, or connection stiffnesses. All connections are visualized in a 3D rendering graphic.
Dimensions, material specifications, and welds that are important for the construction of the connection are visible immediately and can be printed out. It is possible to visualize the connections in RF-/FRAME-JOINT Pro or directly in the RFEM/RSTAB model. 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.
Design of knee joints, T-joints, cross joints, and continuous column connections with I-shaped sections
Import of geometry and load data from RFEM/RSTAB or manual specification of the connection (for example, for recalculation without an existing RFEM/RSTAB model)
Flush top connections or connections with bolt row in extension
Design of positive and negative frame joint moments
Various inclinations of right and left horizontal beams as well as application to frames of duopitch and monopitch roofs
Consideration of additional flanges in a horizontal beam, for example for tapered sections
Symmetrical and asymmetrical T-joints or cross joints
Two-sided connection with different cross-section depth on the right and left
Automatic preliminary design of bolt layout and required stiffening
Optional design mode with possibility to specify all bolt spacing, welds, and sheet thicknesses
Screwability check with adjustable dimensions of used wrenches
Connection classification by stiffness and calculation of the spring stiffness of connections considered in the internal forces determination
Check up to 45 individual designs (components) of the connection
Automatic determination of governing internal forces for each individual design
Controllable connection graphics in rendering mode with specifications of material, sheet thickness, welds, bolt spacing, and all dimensions for construction
Integrated and flexibly extensible settings of National Annexes according to EN 1993-1-8 standard
Automatic conversion of internal forces from structural analysis into respective sections, also for eccentric member connections
Automatic determination of initial stiffness Sj,ini of the connection
Detailed plausibility check of all dimensions, including specifications of input limits (for example, for edge distances and hole spacing)
Optional application of compression forces to a column through contact
Possibility to update the cross-section depth of horizontal beams in case of tapered connections after connection geometry optimization in RF-/FRAME-JOINT Pro
After the design, all results are displayed in clearly arranged result tables; for example, by load case or by node. The governing internal forces are compared with the limit values listed in the DSTV guideline.
You can visualize the joints graphically in the add-on module or in RFEM/RSTAB. In addition to the input and result data, including design details displayed in tables, you can add all graphics into the printout report. This way, comprehensible and clearly arranged documentation is guaranteed.
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 RF-/FRAME-JOINT Pro add-on module designs connections of structures calculated in RFEM/RSTAB. If there is no RFEM/RSTAB structure available, you can define the geometry and loading manually; for example, when checking external calculations, for example.
Designed nodes are usually imported from RFEM/RSTAB. The module recognizes all connected members automatically and assigns a connection type to them. Depending on the connection type, you can define further details of ribs, backing plates, web plates, bolts, welds, and hole spacing. As loads, you can select any load case, load combination or result combination in RFEM/RSTAB.
In the case of the "preliminary design" calculation mode, RF-/FRAME-JOINT Pro performs the first calculation step to suggest applicable layouts. After you select the relevant layout, the module displays all designs in detailed result tables and various graphics.
It is possible to select connection nodes graphically in the RFEM/RSTAB model. The relevant cross-section data and geometry are imported automatically. You can also define the parameters of hollow section connections manually. If necessary, you can modify the sections in the module.
The default angle between struts and chords can be modified as well. The geometric relation of the struts to each other is important for the correct choice of design. This relationship can be defined by specifying a gap between the struts or by overlapping them.
The extensive DSTV guideline is included in the database of the RF-/JOINTS Steel - DSTV add-on module. Each joint is characterized by a unique alphanumeric code.
The possible DSTV connections can be filtered out by the corresponding specifications for the DSTV connection type (IH, IW, IS, IG, and IK) and the used cross-section. This way, it is possible to determine the load-carrying capacity of the selected joint.
After opening the add-on module, it is necessary to select the joint group (Pinned Joints), then the joint category and joint type (web cleat, fin plate, short end plate, end plate with cleat). Then, you can select the nodes for design in the RFEM/RSTAB model. RF-/JOINTS Steel - Pinned automatically recognizes the joint members and determines from its location whether they are columns or beams.
It is possible to exclude particular members from the calculation, if required. Structurally similar connections can be designed for several nodes at the same time. Loads require selection of the governing load cases, load combinations, or result combinations. Alternatively, you can enter the cross‑section and load data manually. In the last input window, the connection is configured step by step.
It is possible to freely model a cross-section using surfaces limited by polygonal lines, including openings and point areas (reinforcements). Alternatively, you can use the DXF interface to import the geometry. An extensive material library facilitates the modeling of composite cross-sections.
Definition of limit diameters and priorities allows for a curtailment of reinforcements. In addition, you can consider the respective concrete covers and prestresses.
Iterative nonlinear calculation of deformations for beam and plate structures consisting of reinforced concrete by determining the respective element stiffness subjected to the defined loads
Deformation analyses of cracked reinforced concrete surfaces (state II)
General nonlinear stability analysis of compression members made of reinforced concrete; for example, according to EN 1992-1-1, 5.8.6
Tension stiffening of concrete applied between cracks
Numerous National Annexes available for the design according to Eurocode 2 (EN 1992-1-1:2004 + A1:2014, see EC2 for RFEM)
Optional consideration of long-term influences such as creep or shrinkage
Nonlinear calculation of stresses in reinforcing steel and concrete
Nonlinear calculation of crack widths
Flexibility due to detailed setting options for basis and extent of calculations
Graphical representation of results integrated in RFEM; for example, deformation or sag of a flat slab made of reinforced concrete
Numerical results clearly arranged in tables and graphical display of the results in the model
Complete integration of results in the RFEM printout report
After the calculation, the module shows clearly arranged tables listing the results of the nonlinear calculation. All intermediate values are included in a comprehensible manner. Graphical representation of design ratios, deformations, concrete and reinforcing steel stresses, crack widths, crack depths, and crack spacing in RFEM facilitates a quick overview of critical or cracked areas.
Error messages or remarks concerning the calculation help you find design problems. Since the design results are displayed by surface or by point including all intermediate results, you can retrace all details of the calculation.
Due to the optional export of input or result tables to MS Excel, the data remain available for further use in other programs. The complete integration of results in the RFEM printout report guarantees verifiable structural design.
The nonlinear calculation is activated by selecting the design method of the serviceability limit state. You can individually select the analyses to be performed as well as the stress-strain diagrams for concrete and reinforcing steel. The iteration process can be influenced by these control parameters: convergence accuracy, maximum number of iterations, arrangement of layers over cross-section depth, and damping factor.
You can set the limit values in the serviceability limit state individually for each surface or surface group. Allowable limit values are defined by the maximum deformation, the maximum stresses, or the maximum crack widths. The definition of the maximum deformation requires additional specification as to whether the non-deformed or the deformed system should be used for the design.
RF-CONCRETE Members
The nonlinear calculation can be applied to the ultimate and the serviceability limit state designs. In addition, you can specify the concrete tensile strength or the tension stiffening between the cracks. The iteration process can be influenced by these control parameters: convergence accuracy, maximum number of iterations, and damping factor.
The nonlinear deformation analysis is performed by an iterative process considering the stiffness in cracked and non-cracked sections. The nonlinear reinforced concrete modeling requires definition of material properties varying across the surface thickness. Therefore, a finite element is divided into a certain number of steel and concrete layers in order to determine the cross-section depth.
The mean steel strengths used in the calculation are based on the 'Probabilistic Model Code' published by the JCSS technical committee. It is up to the user whether the steel strength is applied up to the ultimate tensile strength (increasing branch in the plastic area). Regarding material properties, it is possible to control the stress-strain diagram of the compressive and tensile strength. For the concrete compressive strength, you can select a parabolic or a parabolic-rectangular stress-strain diagram. On the tension side of the concrete, it is possible to deactivate the tensile strength as well as to apply a linear-elastic diagram, a diagram according to the CEB-FIB model code 90:1993, and concrete residual tensile strength considering the tension stiffening between the cracks.
Furthermore, you can specify which result values should be displayed after the nonlinear calculation at the serviceability limit state:
Deformations (global, local based on non-/deformed system)
Crack widths, depths, and spacing of the top and bottom sides in principal directions I and II
Stresses of the concrete (stress and strain in principal direction I and II) and of the reinforcement (strain, area, profile, cover, and direction in each reinforcement direction)
RF-CONCRETE Members:
The nonlinear deformation analysis of beam structures is performed by an iterative process considering the stiffness in cracked and non-cracked sections. The material properties of concrete and reinforcing steel used in the nonlinear calculation are selected according to a limit state. The contribution of the concrete tensile strength between the cracks (tension stiffening) can be applied either by means of a modified stress-strain diagram of the reinforcing steel, or by applying a residual concrete tensile strength.