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• ### How can I additionally model welds for the connection of two surfaces with a contact solid?

Since the boundary surfaces of contact solids can only be of the Null Surface type, it is necessary to model additional surfaces with a section. The following is an example for this.

There is a reinforcement of a plate with an additional plate. Both plates are connected by means of a contact solid:

In order to simulate a weld, borders are required on both plates:

You can simply create the bottom border by inserting a new rectangular surface. In this case, the program asks whether the surface should be integrated into the base surface, which must be confirmed by clicking Yes. There are then two openings in the bottom surface; one in the outermost surface where lies the surface for the border, and another in the surface for the border where lies the bottom surface of the contact solid:

For the upper border, it is also necessary to create a new surface, and the opening to the upper surface of the contact solid must be inserted manually:

After creating the borders, you can insert the actual surfaces for the weld:

If the reinforcing plate is subjected to tension now, the modeled weld transfers the tension stresses:

• ### I would like to use surface releases to model a bolt connection, which can only absorb compressive stresses from the support. Unfortunately, I cannot do this because my model is always unstable. Is there a model as a template?

The best way is to create the bolt as a single solid and not from several partial solids (within the hole). Then, you can arrange the surface release between the contact surfaces of the solids. In the case of a bolt connection, the setting for the surface release type would have to be defined with a nonlinearity in the uz direction.

As an alternative, you can also enter releases and spring stiffnesses for the other directions.

• ### The design of my connection is not possible because of an incorrect geometry input. What can I do?

The RF‑/FRAME‑JOINT Pro add-on module designs rigid bolt connections between columns and horizontal beams, and classifies these connections. The rigid bolt connections are designed with the ultimate load method according to Eurocode 3 or DIN 18800.

The dimensions of an end plate can be defined in the add-on module. However, the bolts in the extensions are only possible in the extended top.

A bolt row in the extended bottom is not provided, and therefore the error message appears.

You can check the minimum dimension under the design hints in the add-on module.

The desired geometry can be entered in the RF‑/JOINTS Steel - Rigid add-on module.

• ### For design in FRAME‑JOINT Pro, I get Error No. 30011 "The selected nodes have different geometry [...]". How can I design my connection?

The program checks whether the assignment of members is allowed for the calculation. If this is not the case, a footnote is displayed, which is explained in the "Comment" column. You have probably used a cross-section that is not intended for the connection design.

In our example, Note 23 is displayed and then the left beam is assigned manually: "Left Beam: Cross-section is not an I-section."

In Window 1.2 Cross-Sections, you can open the cross-section library to check which cross-sections can be selected for the frame joint type (activate the manual definition of geometry in Window 1.1 "General Data").

• ### Can I consider the normal force when designing a rigid end plate connection according to the DSTV guideline?

In the first place, the typified moment-resisting connections of the DSTV guideline are not designed for loading by a normal force. However, a load of up to 5% of the plastic normal force resistance of the connected beam may be neglected according to the instructions given in the guideline. If there is a higher axial force contained in the beam, a warning message also appears in RF‑/JOINTS Steel - DSTV.

With the additional volume of the 2018 guideline, additional moment-resistant connections of the IM designation were added. In the beam-to-beam connection type, they are also designed to resist the normal forces. If you design such a connection, the normal force resistance design including the MN interaction appears instead of the warning message.

For beam-column connections, the normal force resistance of column components is not included in the table values according to the DSTV guideline. Therefore, the connection must be designed separately again. Consequently, the warning message appears anyway. As an alternative, you can use RF‑/JOINTS Steel - Rigid.

• ### It is not possible to calculate the connection that I have created. Error No. 30863 appears. What should I do?

You have probably forgotten to define "extra bolts" in the upper and lower flange of the beam for the end plate connection. If this function is not activated, JOINTS only allows you to arrange the bolts within both beam flanges.

• ### In RF‑/JOINTS Steel - DSTV, I get the notes "Wrong geometry" and "Invalid material." Which entries do I have to adjust?

The connections in the RF‑/JOINTS Steel - DSTV module are typical steel connections for the transmission or introduction of moments and shear forces.

If the note "Wrong geometry" appears, check whether the connection geometry meets the requirements of the typified connections. This can be also caused by inconsistencies in the model input. In the example, a small deviation in the coordinates of the Y‑axis leads to the incorrect model geometry.

If the message "Invalid material" appears, check whether the material is provided for the typified connection. For cross-sections and metal sheets, you can select the material S 235 or S 355 for these connections.

• ### How can I model and design general bolted connections with the surface and solid elements in RFEM?

In RFEM, you can model and design connections with the individual dimensions. The video on the left shows an example of modeling and calculation of a rigid bolted connection by using member and surface elements as well as contact solids.

Furthermore, you can define bolt prestressing forces and perform plastic design (RF‑MAT NL add-on module required), for example.

• ### Are the models and presentations from Info Day 2015 freely available, and can you send them to me?

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#### First Steps

We provide hints and tips to help you get started with the main programs RFEM and RSTAB.

#### Wind Simulation & Wind Load Generation

With the stand-alone program RWIND Simulation, wind flows around simple or complex structures can be simulated by means of a digital wind tunnel.

The generated wind loads acting on these objects can be imported to RFEM or RSTAB.

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