#### 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.

• ### Why is the imperfection always displayed graphically with a displacement at the column base?

In the graphic, imperfections are always oriented on a support. In the attached model and in Figure 01, the only support of an imperfection is defined at the column head. Therefore, the imperfection is oriented at this point.

Since the graphical imperfection is virtually an equivalent load, the display is only of visual relevance in this case. The display is not important for the calculation.

In order to orientate the imperfection graphically to the upper column head, you could use a rigid member, for example, and arrange the support there (Figure 02).
• ### I have manually defined a snow load of 5 kN/m² in the RX‑TIMBER program. However, the calculation uses a load of 4 kN/m². Why is the defined snow load not applied?

According to EN 1991‑1‑3, the snow load must be multiplied by the factor of 0.8 for the snow load on a roof. Therefore, the following load results:

sk = 5 kN/m² × 0.8 = 4 kN/m²

If the load has already been calculated for the roof, you can enter the load completely under the user-defined loads. This is shown in Figure 01 and in the video.

• ### Is it also possible to transfer loads and load cases by using the .stp interface (regulated according to DSTV)?

004369

The export of a member with loads is shown in the attached video.
• ### When importing a .stp (DSTV) file that I have exported to RFEM/RSTAB, I get an error message shown in the figure. No cross-sections are exported. Why?

004367

In order to carry out the import in RFEM/RSTAB by using the DSTV interface, the program requires the nodes where the cross-sections can be located.

It often happens, that members are only selected in the case of the "Export only selected objects" option (Figure 02). In this case, the nodes are missing in the selection. The model cannot be created.

Therefore, you have to select all objects that are necessary for the description of the model by using the "Select" → "Related Objects" option (Figure 03). Then, the import is carried out properly.
• ### How do I create a user-defined material in the RX‑TIMBER program?

In RX‑TIMBER, you can create a user-defined material as a new material in the material library (see the figure), similar to the programs RFEM/RSTAB.

In contrast to RFEM/RSTAB, the category is set to "timber" in this case.
• ### Is it possible to perform fire resistance design of cross-laminated timber panels in RF‑LAMINATE?

Fire resistance design is not implemented in the RF‑LAMINATE add-on module by default.

However, you can calculate the charring rates yourself and consider them accordingly in the module. In the following example, this is explained on a simple plate.

Structural system (Figure 01):

• Span 5 m
• Plate width 2 m
• LC2 (medium) 2.5 kN/m²
• 3 layers
• S1 35 mm C24
• S2 20 mm C24
• S3 35 mm C24
The information regarding the correction factors and stiffnesses can be found in the attached file.

Factors for fire resistance:

• Charring rate ß0 = 0.65 mm/min
• Pyrolysis zone k0d0 = 7 mm
• Charring time t = 30 min
• Effective thickness def=t ß0+k0d0=30 min × 0.65 mm/min+7 mm = 26.5 mm
Remaining thickness of Layer 3 = 35 − 26.5 = 8.5 mm > 3 mm → thickness may be applied. (Figure 02)

Because of the modified layer thicknesses, a new stiffness matrix results, which is applied in RFEM for accidental combinations with the characteristic stiffness values. For the ultimate limit state, the design values are calculated here (Figure 03).
• ### Is it possible to perform a detailed analysis of connections, supports, or reinforcements of cross‑laminated timber plates in RF‑LAMINATE?

In principle, it is also possible to perform detailed analysis in RF‑LAMINATE. In the case of a very high shear distortion, for example, it can be reasonable to use orthotropic solids for modeling. The video shows a simple modeling and result evaluation of a layer structure by using solids.

A criterion, as of when is the modeling using solids useful, is the shear correction factor. Further information and other criteria can be found in the following FAQ:

• ### How can I consider the flexibility of a continuous beam with slotted dowel connections?

The easiest way to consider this is to use the RF‑/JOINTS Timber - Steel to Timber add-on module. For this purpose, the module decomposes the original connection, and creates a new structural system that considers the flexibility accordingly. In this case, the ultimate limit state, the serviceability limit state, and the accidental design situations are considered separately.
• ### Where can I set the Poisson's ratio?

The Poisson's ratio is set under the material by using the Edit Material dialog box.
• ### When displaying the result diagrams on a member (the "rib" type), there is the option to display the internal force VL. What is this value and how is it calculated?

The force VL is the longitudinal shear force between the top surface and the member. It is calculated as an integrated shear flow between the plate and the member at a particular point on the member.

For the simplified example provided here, the resulting cross-section values for the integration width of 10 cm are as follows:

• $I_y=\frac{b\times h^3}{12}=\frac{10 cm\times20 cm^3}{12}=6,666.67 cm^4$
• $S_y=h_1\times b\times((h-e_z)-\frac{h_2}2)=10 cm\times10 cm\times((20 cm-10 cm)-\frac{10 cm}2)=500 cm^3$
• $\tau=V_L=\frac{V_z\times S_y}{I_y\times b}=\frac{5.53 kN\times500 cm^3}{6,666.67 cm^4}=0.415 kN/cm=41.5 kN/m$
The integration width has been set to the total of 10 cm.

Values:
• Iy second moment of area
• Sy statical moment
• h1 height of the upper cross-section part
• h2 height of the lower cross-section part
• ez centroidal distance
• h total height
The values can be adjusted for a T-beam.

1 - 10 of 48

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. ”