#### Further Information

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• ### Is it possible to perform a fire resistance design for cross-laminated timber panels with RF-LAMINATE?

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FAQ 004349 EN

By default, the fire resistance design is not implemented in the RF-LAMINATE module.

However, it is possible to calculate the burn-up rates yourself and consider them accordingly in the module. The following example explains this on a simple plate.

System (Figure 1):

• Span 5m
• Slab width 2m
• LC1 (permanent) 1kN/m² plus self-weight
• LC2 (medium) 2.5kN/m²
• 3 layers
• S1, 35mm, C24
• S2, 20mm, C24
• S3, 35mm, C24
Information regarding the correction factors and stiffnesses can be found in the attached file.

Factors Fire Resistance:

• Burning rate ß0 = 0.65mm/min
• Pyrolysis zone k0 d0 = 7 mm
• Burning time t = 30min
• Effective thickness def = t ß0 + k0 d0 = 30min x 0.65mm/min + 7mm = 26.5mm
Residual thickness of layer 3 = 35-26.5 = 8.5mm> 3mm => thickness may be applied. (Photo 2)

Due to the changed layer thicknesses, a new stiffness matrix results, which is applied in RFEM for the Extraordinary Combinations with characteristic stiffness values. Design values are calculated for the ultimate limit state (Figure 3).
• ### After splitting a column with intermediate nodes, I get different results than before in the RF-/CONCRETE Columns add-on module. Why?

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FAQ 004348 EN

The reason for the different results is probably due to the settings of the effective lengths for the stability analysis. According to the default setting, they are determined automatically in the RF-/CONCRETE Columns add-on module. However, this method does not work for separate members and no stability analysis is performed (a corresponding warning message appears).

If the effective lengths have been entered manually, they only apply to the single member. To perform a correct stability analysis for the column as an entire structural component, it has to be defined as a set of members.

• ### Is it possible to perform a detailed analysis of connections, supports, or reinforcements of cross‑laminated timber plates in RF‑LAMINATE?

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FAQ 004347 EN

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?

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FAQ 004346 EN

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 situation are considered separately.
• ### Is it possible to generate a parts list in RFEM?

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FAQ 004345 EN

This is not possible directly in RFEM, but the RF‑/STEEL EC3 add-on module allows you to create a list of steel parts. In Details of the add-on module, you can specify whether the parts list should apply to all members or only for members to be designed. Then, you can simply carry out the calculation and the parts list will be displayed. It is also possible to export the parts list to Excel and further edit it.
• ### I have set a variable load distribution for a generated load. This should be applied incrementally in a certain direction. However, the load is not stepped, but is displayed with a linear distribution. How can I display the load correctly?

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FAQ 004344 EN

In order to display the loads correctly, it is necessary to make some adjustments. In the case of an incrementally applied load, the boundary of the area load plane may only be defined in sections (by load increment). Otherwise, the load is distributed linearly over the entire area load plane.
• ### Why are there the intermediate results for some members exactly at the member end node in the result table of member internal forces?

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FAQ 004343 EN

The result display of intermediate values is generally linked to the member division property. Also, member loads defined in sections in RFEM generate further intermediate results. For example, if a member load defined in sections is distributed from the member start to the member end, the intermediate results are obtained at the member end nodes.

• ### In RF-/DYNAM PRO - Forced Vibrations, why does my time diagram function formula output incorrect values which appear to be off by only a factor?

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FAQ 004342 EN

In the Dlubal programs, all values are stored internally based on SI units. When a user changes the units in the program to metric or imperial, SI units are still used internally and only the value displayed in the interface is modified. Therefore, all values set in the time diagram function also default to SI units unless the user clarifies an alternative unit.

Let's look at a simple example shown in Figure 1 where the parameter x = 1 ft has been set in RFEM.

In RF-DYNAM PRO - Forced Vibrations, the time diagram function is defined as k(t) = 1*x where 1 is the multiplier (1/ft) to convert x to a dimensionless value. You can see in Figure 2, because all values default to SI units, the Multiplier column produces values of 0.305 instead of the correct value of 1.000.

In order to correct the issue, the user only needs to specify the units of the multiplier as (1/ft) in the function equation. This can be done with the formula modification k(t) = 1/1[ft]*x as shown in Figure 3. Notice the Multiplier column now shows the correct values of 1.000.

In summary, when using units in the program other than SI units, coefficients or multipliers in the time diagram function should be accompanied with alternative units defined in brackets.

• ### Where can I set the Poisson's ratio?

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FAQ 004341 EN

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?

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FAQ 004340 EN

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.

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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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