#### Further Information

In addition to our technical support (e.g. via chat), you’ll find resources on our website that may help you with your design using Dlubal Software.

Receive information including news, useful tips, scheduled events, special offers, and vouchers on a regular basis.

• ### I have defined a nonlinear line support with failure. Implausible results are displayed during the result evaluation. What can I do?

Similarly to surfaces, there are various smoothing options for displaying the results of support reactions. For a nonlinear support, you should always select the actual distribution to display the results.
• ### How can I set as quickly as possible that the load combinations generated by the program will be calculated according to the geometrically linear analysis, for example?

004331

In the "Edit Load Cases and Combinations" dialog box, you can specify in the bottom right of the "Combination Expressions" tab which method of analysis should be used as the basis for the generated load combinations. By default, the linear calculation according to the geometrically linear analysis is preset for load cases and the nonlinear calculation according to the second-order analysis for load combinations.

Thus, you can quickly determine whether the load case or the load combination is calculated according to the geometrically linear, second-order, or large deformation analysis. The postcritical analysis option allows you to carry out the stability analysis according to the large deformation analysis with regard to the post-critical failure of the entire structure.

In case the model includes cable members, the calculation according to the large deformation analysis is preset in all cases.
• ### What happens if I activate the "Soil failure" function in RF-SOILIN?

The zero coefficient of structural soil strength can be used for better convergence of deeper excavations or small loading. Damaged soil have no structural soil strength. Therefore, it better picture damaged subsoil in the upper layers with this function. The possible entry for the depth of the soil failure is from 0.0 m to 1.0 m.
• ### What is the meaning of 'Shear Failure in Glued Contact Surface' in the details of the RF-LAMINATE add-on module?

In the case of cross laminated timber panels not glued to the narrow sides and a wall-like structural behaviour, the torsion stress in the glued joints is often decisive. This design is performed according to the explanations in the literature reference below according to the following equation.

$\eta_x=\frac{\tau_{tor,x}}{f_{v,tor}}+\frac{\tau_x+\tau_{xz}}{f_R}=\frac{\displaystyle\frac{3\ast n_{xy}}{b(n-1)}}{f_{v,tor}}+\frac{{\displaystyle\frac{\frac{\partial n_x}{\partial x}}{n-1}}+\tau_{xz}}{f_R}\leq1$

Values:
• b board width
• n number of board layers
• nxy shear in pane plane
• $\frac{\partial n_x}{\partial x}$ shear of board layers
• $\tau_{xz}$ shear in thickness direction
• fR rolling shear strength
• fv,tor torsional shear strength
For the y-direction, the design is analogous but with the values for the y-direction.
• ### What is the note 40162 saying regarding the shear strengths of Binderholz company?

For the superstructures of the manufacturer Binderholz, as soon as the slabs are defined without glue at narrow sides and design of shear failure is calculated in the wall plane, the shear strengths are calculated according to the following equation.

$f_{v,k}=\left\{\begin{array}{l}\begin{array}{c}3,5\\8,0\frac{D_{net}}D\\\end{array}\\2,5\frac{(n-1)(a²+b²)}{6Db}\end{array}\right.$

Values:
D element thickness
Dnet sum of longitudinal and transverse layer thicknesses in the element
n number of board layers
a = b width of the boards in the longitudinal or transverse layers

All values in N/mm². For more detailed information, check the manufacturer's approval.
• ### How do I apply prestress to tension members?

To correctly combine the planned prestress with the other load cases, define a suitable load case and apply a "pulling" strain load to the members concerned. The pulling strain load can be, for example:

• a negative temperature load Tc distributed uniformly over a cross‑section,
• a negative axial strain ε,
• a negative axial displacement Δl,
• a positive initial prestress V, or
• a positive final prestress V (in RFEM only).

The input by using the axial displacement is the most comprehensible input as you can directly measure the displacement at the turnbuckle of the tension member.

• ### How can I determine the post-critical load of a structural system with a post-critical analysis?

004122

There is currently no direct way to determine the post-critical load. It is important that there are also several different states, and thus that there can be several local post-critical loads.

You can assign load increments to the structure and retroactively view the individual load increments, and thus find a load factor close to the post-critical failure (depending on the number of load increments).

In the attached model, 20 load increments and saving of the intermediate results have been set (Figure 01). Figure 02 shows Load Increment 10 as the last load increment before the post-critical failure, and Figure 03 shows the first load increment after the post-critical failure, whereby the deformation is significantly higher.

• ### In a nonlinear structural system, some load cases do not converge. However, load combinations can be calculated without any problems. What could be the reason for this?

When defining nonlinearities, such as support failure under tension, it may happen that some load cases cannot be calculated. If these are the loads that cannot exist without other stabilizing loads, the problem resolution is simple: You can set the load cases to "Not To Be Calculated." As a result, the load combinations are only considered in the "Calculate All" option of the calculation process. This is possible because some loads can never appear without a dead load, for example.

In the attached example, it is clearly evident that the structural system would buckle in the Wind load case, and thus no convergence is found. In contrast to this, it is possible to calculate the load combination, where the dead load and the wind are combined without any problem because the dead load stabilizes the system.
• ### I have modeled a continuous beam. One of the supports should only act as of the deformation of 10 mm. How can I set such a nonlinearity?

In this case, it is recommended to use the definition of slippage. For this, select Partial Activity as a "Nonlinearity" in the "Edit Nodal Support" dialog box. In the "Nonlinearity - Partial Activity" dialog box, you can define the slippage in the respective zone. For checking purposes, there is a diagram, see Figure 01.

• ### What is the critical load factor and how is it possible to determine it?

A critical load factor specifies which factor can be used to increase the load until the structural system fails. If it is smaller than one, the calculation according to the second-order analysis is usually unstable as the structural system is already subjected to the critical load. This factor is also referred to in standards. For example, Eurocode 3 specifies that the calculation according to the second-order analysis is no longer necessary as of the critical load factor of 10.
The critical load factor can be determined by using the RF‑STABILITY or RSBUCK add-on module.

1 - 10 of 31

If not, contact us via our free e-mail, chat, or forum support, or send us your question via the online form.

#### 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.

#### Your support is by far the best

“Thank you for the valuable information.

I would like to pay a compliment to your support team. I am always impressed how quickly and professionally the questions are answered. I have used a lot of software with a support contract in the field of structural analysis, but your support is by far the best. ”