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.
Did you know? In the Design Supports, you can now define fully threaded screws as transversal compression stiffening elements for the "Compression Perpendicular to Grain" design. In this case, the pressing-in and buckling of the bolts is analyzed.
Moreover, the design shear resistance is checked in the plane of the screw tip. The angle of dispersal can be considered as linear under 45° or nonlinear (according to Bejtka, I. (2005). Verstärkung von Bauteilen aus holz mit vollgewindeschrauben. KIT Scientific Publishing.).
Graphical display of the connection geometry that is updated in parallel with the input
The Steel Joints Template included in the add-on allows you to select from several connection types and, and once selected, it will be applied to your model.
Wide range of cross-section shapes: Includes I-sections, channel sections, angles, T-sections, built-up cross-sections, RHS (rectangular hollow sections), and thin-walled sections
The Template covers connections from three general categories: Rigid, Pinned, Truss
Automatic adaptation of the connection geometry, even if the structural components are subsequently edited, based on the relative relation of the components
Beam to Column joint category: connection possible as joint of the beam to the column flange as well as joint of the column to the girder flange
Beam to Beam joint category: design of beam joints as both moment-resisting end plate connections and rigid splice connections possible
Automatic export of model and load data possible from RFEM or RSTAB
Bolt sizes from M12 to M36 with strength grades 4.6, 4.8, 5.6, 5.8, 6.8, 8.8, and 10.9 as long as the strength grades are available in the selected National Annex
Almost any bolt spacing and edge distances (a check of the allowable distances is performed)
Beam strengthening with tapers or stiffeners on the top and bottom surfaces
End plate connection with and without overlap
Connection with pure bending stress, pure normal force load (tension joint), or combination of normal force and bending possible
Calculation of connection stiffnesses and check if a hinged, semi-rigid, or rigid connection exists
End plate connection in a beam-column setup
Joint beams or columns can be stiffened with tapers on one side or with stiffeners to one or both sides
Wide range of possible stiffeners of the connection (for example, complete or incomplete web stiffeners)
Up to ten horizontal and four vertical bolts possible
Connected object possible as constant or tapered I-section
Designs:
Ultimate limit state of the connected beam (such as shear or tension resistance of the web plate)
Ultimate limit state of the end plate at the beam (for example, T-stub under tensile stress)
Ultimate limit state of the welds at the end plate
Ultimate limit state of the column in the area of the connection (for example, column flange under bending – T-stub)
All designs are performed according to EN 1993-1-8 and EN 1993-1-1
Moment-resisting end plate joint
Two or four vertical and up to 10 horizontal bolt rows
Joint beams can be stiffened with tapers on one side or with stiffeners to one or both sides
Connected objects are possible as constant or tapered I-sections
Designs:
Ultimate limit state of the connected beams (such as shear or tension resistance of the web plates)
Ultimate limit state of the end plates at the beam (for example, T-stub under tensile stress)
Ultimate limit state of the welds at the end plates
Ultimate limit state of the bolts in the end plate (combination of tension and shear)
Rigid splice plate connection
For the flange plate connection, up to ten bolt rows one behind the other possible
For the web plate connection, up to ten bolt rows possible each in vertical and horizontal directions
Material of the cleat can be different from the one of the beams
Designs:
Ultimate limit state of the joint beams (for example, net cross-section in the tension area)
Ultimate limit state of the cleat plates (for example, net cross-section under tensile stress)
Ultimate limit state of the single bolts and the bolt groups (for example, shear resistance design of the single bolt)
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
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.
All joint types are considered with the moment release at the column flange, or at the column web in the case of a rotated column. Therefore, the module determines the eccentric moment of a web cleat and fin plate connection, which additionally affects the bolt group at the girder flange.
Further eccentric moments may result from the locations of the angles and sheets. In the case of cleat connection, the forces are transferred separately. Shear forces act on the cleat; tension forces and stabilizing moment are assigned to the bolts. Before the calculation, the connection is checked for geometrical plausibility; for example, the bolt hole spacing and edge distance of the bolts.
There are various options available for beam modeling. A roof type determines the exact purlin location for wind and snow generation.
Two beam types are available: continuous beam and purlin. If you select the continuous beam, it is possible to define several hinge conditions of the beam. If you select the purlin, it is not possible to modify hinge conditions. In this case, the calculation considers a double cross-section in the coupling zone. In addition, several coupling elements are available in the purlin settings:
Nails (prebored/not prebored)
Ring and plate connectors and bolts
Screw connection with fastening system WT from SFS intec
User-defined specification using characteristic strength
The relevant timber grade of the material can be selected from the material library. All material grades for glulam, hardwood and softwood timber specified in EC 5 are available. Furthermore, you have the option to generate a strength class with user-defined material properties and thus extend the library.A comprehensive and extensible material library can also be used for entering permanent loads (for example, roof structure).
Generators integrated in RX-TIMBER Purlin allow for convenient generation of various wind and snow load cases. By clicking the information buttons, the map of wind and snow zones for the relevant country is displayed. The corresponding zone can be selected with a double-click. Load cases can be checked graphically.
However, you can enter load specifications manually as well. According to the generated loads, the program automatically creates combinations for the ultimate and serviceability limit states as well as for fire resistance design in the background.