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.
Frequently Asked Questions (FAQ)
Search FAQ
Further Information
Customer Support 24/7

Answer
Fire resistance design is not implemented in the RF‑LAMINATE addon 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
 LC1 (permanent) 1 kN/m² plus dead load
 LC2 (medium) 2.5 kN/m²
 3 layers
 S1 35 mm C24
 S2 20 mm C24
 S3 35 mm C24
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 ß_{0}+k_{0}d_{0}=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). 
Answer
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:

Does the RF‑LAMINATE program consider the shear correction factor for crosslaminated timber plates?
Answer
The shear correction factor is considered in the RF‑LAMINATE addon module by using the following equation.
$k_{z}=\frac{{\displaystyle\sum_i}G_{xz,i}A_i}{\left(\int_{h/2}^{h/2}E_x(z)z^2\operatorname dz\right)^2}\int_{h/2}^{h/2}\frac{\left(\int_z^{h/2}E_x(z)zd\overline z\right)^2}{G_{xz}(z)}\operatorname dz$with $\int_{h/2}^{h/2}E_x(z)z^2\operatorname dz=EI_{,net}$The calculation of shear stiffness can be found in the English version of the RFLAMINATE manual, page 15 ff.For a plate with the thickness of 10 cm in Figure 01, the calculation of the shear correction factor is shown. The equations used here are only valid for simplified symmetrical plate structures!Layer z_min z_max E_x(z)(N/mm²) G_xz(z)(N/mm²) 1 50 30 11,000 690 2 30 10 300 50 3 10 10 11,000 690 4 10 30 300 50 5 30 50 11,000 690 $\sum_iG_{xz,i}A_i=3\times0.02\times690+2\times0.02\times50=43.4N$$EI_{,net}=\sum_{i=1}^nE_{i;x}\frac{\mbox{$z$}_{i,max}^3\mbox{$z$}_{i,min}^3}3$$=11,000\left(\frac{30^3}3+\frac{50^3}3\right)+300\left(\frac{10^3}3+\frac{30^3}3\right)$$+11,000\left(\frac{10^3}3+\frac{10^3}3\right)+300\left(\frac{30^3}3\frac{10^3}3\right)+11,000\left(\frac{50^3}3\frac{30^3}3\right)$$=731.2\times10^6 Nmm$$\int_{h/2}^{h/2}\frac{\left(\int_z^{h/2}E_x(z)zd\overline z\right)^2}{G_{xz}(z)}\operatorname dz=\sum_{i=1}^n\frac1{G_{i;xz}}\left(χ_i^2(z_{i,max}z_{i,min})\;χ_iE_{i,x}\frac{z_{i,max}^3z_{i,min}^3}3+E_{i,x}^2\frac{z_{i,max}^5z_{i,min}^5}{20}\right)$$χ_i=E_{i;x}\frac{z_{i,max}^2}2+\sum_{k=i+1}^nE_{k;x}\frac{z_{k,max}^2z_{k,min}^2}2$χ_{1} 13.75 10^{6} χ_{2} 8.935 10^{6} χ_{3} 9.47 10^{6} χ_{4} 8.935 10^{6} χ_{5} 13.75 10^{6} $\sum_{i=1}^n\frac1{G_{i;yz}}\left(χ_i^2(z_{i,max}z_{i,min})χ_iE_{i,y}\frac{z_{i,max}^3z_{i,min}^3}3+{E^2}_{i,y}\frac{z_{i,max}^5z_{i,min}^5}{20}\right)=$
8.4642 10^{11} 3.147 10^{13} 2.5 10^{12} 3.147 10^{13} 8.4642 10^{11} Total 6.7133 x 10^{13}$k_z=\frac{43.4}{{(731.2e^6)}^2}6.713284\;e^{13}=5.449\;e^{3}$$D_{44}=\frac{{\displaystyle\sum_i}G_{xz,i}A_i}{k_z}=\frac{43.4}{5.449\;e^{3}}=7,964.7 N/mm$This corresponds to the resulting value in RF‑LAMINATE (Figure 02). 
Answer
In order to consider the average regions in the design in RF‑LAMINATE Surfaces, it is always necessary to activate them in the detailed settings of the addon module. See Figure&nbso;01 with the detailed settings in RF‑LAMINATE. 
Answer
In the case of the crosslaminated timber plates that are not glued to the narrow sides, and a walllike structural behavior, the torsion stress in the glued joints is often governing. This design is performed according to the following equation in compliance with the explanations in the literature reference below.$\eta_x=\frac{\tau_{tor,x}}{f_{v,tor}}+\frac{\tau_x+\tau_{xz}}{f_R}=\frac{\displaystyle\frac{3\ast n_{xy}}{b(n1)}}{f_{v,tor}}+\frac{{\displaystyle\frac{\frac{\partial n_x}{\partial x}}{n1}}+\tau_{xz}}{f_R}\leq1$where b is the board width,
 n is the number of board layers,
 n_{xy} is the shear in the layer plane,
 $\frac{\partial n_x}{\partial x}$ is the shear of board layers,
 $\tau_{xz}$ is the shear in the thickness direction,
 f_{R} is the rolling shear strength,
 f_{v,tor} is the torsional shear strength.
For the ydirection, the design is similar, but with the values for the y‑direction. 
Answer
In the case of the structures by the manufacturer Binderholz, the shear strengths are calculated according to the following equation as soon as the slabs are defined without glue at narrow sides and the design of shear failure is calculated in the wall plane.$f_{v,k}=\left\{\begin{array}{l}\begin{array}{c}3.5\\8.0\frac{D_{net}}D\\\end{array}\\2.5\frac{(n1)(a²+b²)}{6Db}\end{array}\right.$whereD is the element thickness,D_{net} is the sum of the longitudinal and transverse layer thicknesses in the element,n is the number of board layers,a = b is the width of the boards in the longitudinal or transverse layers.All values are in N/mm². For more detailed information, check the manufacturer's approval. 
Answer
These factors reduce the torsional stiffness D_{33} as well as the shear stiffness D_{88} of the corresponding stiffness matrix elements of a surface. Since crosslaminated timber is generally not glued at the narrow side, it is also not possible to transfer shear stresses to the timber narrow sides. Thus, the stiffness would be overestimated in this case. For this reason, the stiffness must be reduced accordingly.Some manufacturers have already provided us these values when delivering the layer structures. They result from the internal analysis. The explanation for determining the correction factors is covered in [1]. The analysis of this work has also been included in the Austrian Annex to EN 1995‑1‑1 [2]. The result is shown in Figure 02. The ratio of the timber width (a) to the timber thickness (t_{i}) can be taken from the respective approval. 
Answer
No, it is unfortunately not possible.
The layer structure is assigned to certain surfaces in RF‑LAMINATE.The respective surface obtains then the stiffness defined by this layer structure for the determination of internal forces in RFEM.If you want to perform a calculation with different layer structures, you have to do it in a copy of the file (another model with different layer structure). 
Answer
Displaying Main Support Direction in RFLAMINATE Addon Module
While entering data in the RF‑LAMINATE addon module, there is an option to graphically control the orthotropic direction of each individual layer. To do this, simply place the cursor in the desired row of the corresponding position. Then, a coordinate system is displayed in the surface in the RFEM model (see Figure 01). This is to be interpreted as follows:red axis = xaxis = βvalue of the corresponding layerGenerally, the outer layers specify the main support direction, which is why it is sufficient to only consider the first layer. The red axis specifies the primary loadbearing direction (see Figure 01).Displaying Main Support Direction in RFEM
However, the main support direction can also be interpreted directly in RFEM. For this, you can display the local axis systems of the surfaces in detail (see Figure 02). The orthotropic direction β refers to the local x‑axis of the surface. For the example shown in Figure 03, it has a consequence that the main support direction for the left surface runs from one support to another and the secondary surface direction to the right surface. If you want to change the support direction for the right surface, it is possible to either rotate the local surface axis system (see Figure 04) or create a new structure and rotate the orthotropic direction β by 90° (see Figure 05).If the main support direction is not clearly evident, it is worth taking a look at the stiffness matrix of the surface (see Figure 06). There, it is possible to find the "principal" support direction by means of the bending stiffness, for example. The element D_{11} refers to the local x‑axis of the surface and the element D_{22} refers to the local y‑axis of the surface. 
Answer
The manufacturerspecific structures of crosslaminated timber products are saved in the central library of RF‑LAMINATE.This library is continuously extended and maintained from our side.If a manufacturer is supposed to be added in the library, a sample file can be requested from us to save its structures. Furthermore, it is helpful if the manufacturer provides us with the information on the reduction factors of torsional and shear stiffness, the bonding of narrow sides, and so on.
Contact us
Did you find your question?
If not, contact us via our free email, 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 standalone 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. ”