#### Further Information

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• ### Do I have the opportunity to consider cross-sectional weakenings due to drilling or the like without having to re-model the cross-section in, for example, the DUENQ program?

If the holes are subject to a regular grid, they may be defined by the composite cross sections (Figure 1).

Otherwise it is still possible to reduce the cross section in the properties as a whole (Fig. 2).

Thus, a flat reduction of the stiffness of the cross section is made. Unfortunately, it is not possible to distinguish between reductions in the compression and tension of the cross section.

This possibility results from a reshaping of the cross-section in the DUENQ program or in some modules of the JOINTS family.
• ### Can be dimensioned in RSTAB and RFEM with the add-on module joints, wood-wood joints according to EN 1995-1-1 chapter 8.2.2?

The design of wood joints with pin-shaped fasteners is currently limited to steel-wood joints according to Chapter 8.2.3. Pure wood-wood compounds on shear under consideration of the Johansen theory are therefore currently not possible. Direct wood-wood connections by means of full-thread screws are possible with the module RF- / JOINTS wood - wood to wood with which main secondary beam connections can be calculated.
• ### How can a displacement of bars in a certain connection point be taken into account?

There are basically two options here:

• The use of rod eccentricities, see technical contribution Consideration of rod and surface eccentricities
• In the case of, for example, differently defined rod end joints in combination with different dimensions of offsets, the use of couplings or rigid rods may help, see Figure 1

• ### For a proof with RF glass according to DIN 18008, I have to carry out one calculation with full safety glass and one without fusion for insulating glass with laminated safety glass. Is it possible to do this in a single model with just one pass?

Unfortunately, it is not possible to perform the calculation with and without push group in a file. For each state a separate file must be created.
• ### Why can not I prove a double bend with the module RF- / JOINTS?

In the current regulations, connection means or connections are always detected in one plane only. The reason for this is that the evidence of shear etc. can only be analyzed in the 2D plane. The verification of the bearing evidence, for example, is not possible for off-plane failure.

Since in a three-dimensional calculation also internal forces in v y and v z can occur, it has been proven in practice to allow a small proportion of internal forces in the secondary direction and not fully exploit the connection. However, if the proportion of the lateral force in the secondary direction becomes too high, a detailed investigation with an FE simulation may be necessary.
• ### What does the design information mean:Geometry error left side:End plate of the girder: Lamda2> 1.4Column flange: Lamda2> 1.4Neither the manual nor online, I can find an explanation.

The auxiliary values λ1 and λ2 are required to determine the effective lengths.

These two values are used to determine an α value from Figure 6.19 of EN 1993-1-8, which is then used to calculate the effective lengths (for non-circular flow lines) of the T-stub flanges.
The maximum value for λ1 is 0.9 and the maximum value for λ2 is 1.4 -> see Figure 6.11 of EN 1993-1-8
Based on your geometry, however, the result is, for example, a λ2 of> 1.4 for the end plate
α can only be calculated with the maximum value of 1.4.
• ### Where do I find the connection moments due to the applied rotational restraint in RF‑/STEEL EC3?

Connection moments are not calculated in RF-/STEEL EC3.
• ### How is the rotational restraint stiffness calculated for a non-continuous rotational restraint (for example, purlins) in RF‑/STEEL EC3?

FAQ 002542 EN-US Results STEEL EC3 RF-STEEL EC3

The total rotational spring comprises of several individual rotational springs, which are given in [1] as Equation 10.11.

In the case of a non-continuous rotational restraint by purlins, RF‑/STEEL EC3 takes into account the rotational stiffness due to the connection stiffness CD,A, the rotational stiffness CD,C due to the bending stiffness of the available purlins, and also the rotational stiffness CD,B due to the section deformation, if activated.

Since the execution of the connection is unknown, the infinite value is set by default. The spring stiffnesses are considered as a reciprocal value 1/C, thus giving 'infinitely' the result of spring stiffness = 0. If you know the rotational spring stiffness of the connection, you can specify this value manually.

The rotational stiffness CD,C due to the bending stiffness is determined according to the following formula:

$\begin{array}{l}{\mathrm c}_{\mathrm D,\mathrm C}\;=\;{\mathrm C}_{\mathrm D,\mathrm C}\;/\;\mathrm e\\{\mathrm C}_{\mathrm D,\mathrm C}\;=\frac{\mathrm k\;\cdot\;\mathrm E\;\cdot\;\mathrm I}{\mathrm s}\end{array}$

where

E is the modulus of elasticity
k is the coefficient for position (inner span, outer span)
I is the moment of inertia Iy
s is the distance of the beams
e is the distance of the purlins

The rotational stiffness CD,B due to the bending stiffness is determined according to the following formula:

$\begin{array}{l}{\mathrm c}_{\mathrm D,\mathrm B}\;=\;{\mathrm C}_{\mathrm D,\mathrm B}\;/\;\mathrm e\\{\mathrm C}_{\mathrm D,\mathrm B}\;=\sqrt{\mathrm E\;\cdot\;\mathrm t_{\mathrm w}^3\;\cdot\;\mathrm G\;\cdot\;{\mathrm I}_{\mathrm T,\mathrm G}\;/\;(\mathrm h-{\mathrm t}_{\mathrm f})}\\{\mathrm I}_{\mathrm T,\mathrm G}\;=\mathrm b\;\cdot\;\mathrm t_{\mathrm f}^3\;/\;3\end{array}$

where

E is the modulus of elasticity
tw is the web thickness of the truss or the supported component
G is the G modulus
h is the height of the truss or the supported component
tf is the flange thickness of the truss
b is the truss width
e is the distance of the purlins

The attached example includes two design cases.

Case 1 was designed without taking into account the cross-section deformation. The total rotational spring stiffness is
CD = CD,C = 4,729 kNm/m

Case 2 was designed while taking into account the cross-section deformation. The total rotational spring stiffness is
CD = 72.02 kNm/m

Single spring CD,B = 73.14 kNm/m
Single spring CD,C = 4,729 kNm/m

Total spring:

$\begin{array}{l}\frac1{{\mathrm C}_{\mathrm D}}=\frac1{{\mathrm C}_{\mathrm D,\mathrm B}}+\frac1{{\mathrm C}_{\mathrm D,\mathrm C}}\;=\;\frac1{73.14}+\frac1{4,729}\\{\mathrm C}_{\mathrm D}\;=72.02\;\mathrm{kNm}/\mathrm m\end{array}$

• ### Where can I find the internal forces at certain nodes in the printout report?

The easiest way to find the internal forces at these nodes is to print the pictures of members into the printout report.

If this solution is not an option, you can also find the values in the result table 4.1 in the printout report. Since the extreme values are only activated by default, it is still necessary to activate nodal values in the selection.

It is usually not reasonable to include the internal forces of all member in the printout report. Therefore, you can only select the members that are relevant to you.

• ### I have designed a steel connection using RF‑JOINTS and then created a model to compare it in RFEM. Why are the results not identical?

RF-JOINTS performs an idealized design of a steel connection according to the standard, which cannot be easily compared with an exact FE calculation.

Thus, the following conditions must be met:

• Consideration or exclusion of friction/compression/tension within the contact solid (tab "Solid") as well as for the bolts modeled subsequently
• Consideration of internal forces and deformations within the subsequently modeled end plates or similar, which causes redistribution of bolt forces in the FE calculation (in contrast to the idealized design in RF‑JOINTS)
This can be corrected by rigid connection objects, for example (an end plate as a rigid surface).
• Uniform load introduction into the FE model, for example, by using rigid members or rigid surfaces as described in the article "FEM Modeling Approaches of Rigid Connections"

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