 #### 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.

• ### Is it possible with RF-LAMINATE to perform a detailed analysis of connections, supports or reinforcements of cross-laminated timber panels?

New FAQ 004347 EN-US

In principle, RF-LAMINATE can also be used for detailed analyzes. For example, in the case of a very high shear strain, it may be useful to perform the modeling using orthotropic solids. The video shows the simple modeling and result evaluation of a layer structure by means of solids.

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

New FAQ 004346 EN-US

The easiest way to consider this is to use the RF-/JOINTS Timber - Steel to Timber module. For this purpose, the module dissolves the original connection and creates a new static system that takes flexibility into account accordingly. The consideration is separately for load-bearing capacity, serviceability and exceptional.
• ### Where can I set the Poisson's ratio?

New FAQ 004341 EN-US

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?

New FAQ 004340 EN-US

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.
• ### Does the program RF-LAMINATE consider the shear correction factor for cross-laminated timber slabs?

FAQ 004281 EN-US

The shear correction factor is taken into account in the RF-LAMINATE program 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 the shear stiffness itself can be found on page 15 of the English version to the manual of RF-LAMINATE as follows:

For the 10 cm thick plate in Figure 1, the calculation of the shear correction factor is shown. The equations used here are only valid for the simplified symmetrical plate structures!

 Layer z_min z_max E_x (z) (N/mm²) G_xz (z) (N/mm²) 1 -50 -30 11000 690 2 -30 -10 300 50 3 -10 10 11000 690 4 10 30 300 50 5 30 50 11000 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$}_{i,min}^3}3$

$=11000\left(\frac{-30^3}3+\frac{50^3}3\right)+300\left(\frac{-10^3}3+\frac{30^3}3\right)$

$+11000\left(\frac{10^3}3+\frac{10^3}3\right)+300\left(\frac{30^3}3-\frac{10^3}3\right)+11000\left(\frac{50^3}3-\frac{30^3}3\right)$

$=731,2\times10^6Nmm$

$\int_{-h/2}^{h/2}\frac{\left(\int_z^{h/2}E_x(z)zd\overline z\right)^2}{G_{xz}(z)}\operatorname dz=\sum_{i=1}^n\frac1{G_{i;xz}}\left(χ_i^2(z_{i;max}-z_{i,min})\;χ_iE_{i,x}\frac{z_{i,max}^3-z_{i,min}^3}3+E_{i,x}^2\frac{z_{i,max}^5-z_{i,min}^5}{20}\right)$

$χ_i=E_{i;x}\frac{z_{i;max}^2}2+\sum_{k=i+1}^nE_{k;x}\frac{z_{k,max}^2-z_{k,min}^2}2$

 χ1 13.75 106 χ2 8.935 106 χ3 9.47 106 χ4 8.935 106 χ5 13.75 106

$\sum_{i=1}^n\frac1{G_{i;yz}}\left(χ_i^2(z_{i,max}-z_{i,min})-χ_iE_{i,y}\frac{z_{i,max}^3-z_{i,min}^3}3+{E^2}_{i,y}\frac{z_{i,max}^5-z_{i,min}^5}{20}\right)=$

 8.4642 1011 3.147 1013 2.5 1012 3.147 1013 8.4642 1011

Total 6.7133 x 1013

$k_z=\frac{43,4}{{(731,2e^6)}^2}6,713284\;e^{13}=5,449\;e^{-3}$

$D_{44}=\frac{{\displaystyle\sum_i}G_{xz,i}A_i}{k_z}=\frac{43,4}{5,449\;e^{-3}}=7964,7N/mm$

This corresponds to the value output in RF-LAMINATE (Figure 2).
• ### Is it possible to define different stiffnesses for tension and compression between two surfaces in the diagram of a line release?

FAQ 004243 EN-US

It is possible to define different properties in the tension and compression area of a line release as shown in Figure 01.

However, it is necessary to consider a special feature regarding the released surface when releasing lines between two surfaces. The attached model involves an identical line release. The bottom surface 1 is released for the left model, but the top surface 4 for the right model. For both surfaces, the local y-axis of the surface is aligned parallel to the global z-axis.

The deformation diagram results in completely different deformations for both models.

In the left model with the lower released surface, the pressed area is very soft. For this axis orientation, the reaction force of surface 2, which presses surface 1 from above, is very soft.

In the model on the right, the upper surface is released, so that the reaction force of surface 4, which presses surface 3 from above, is very stiff.

FAQ 004218 EN-US

Basically, all cross-sections of the solid and hybrid cross-section groups can be designed in the RF-/TIMBER Pro program. In Figure 01, they are displayed on the right.

For more complex asymmetrical cross-section shapes, it may be necessary to adjust the allowable inclination of principal axis on a user-defined basis in the add-on module (see Figure 02).

• ### What is the meaning of 'Shear Failure in Glued Contact Surface' in the details of the RF-LAMINATE add-on module?

New FAQ 004206 EN-US

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?

FAQ 004191 EN-US

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 to evaluate the internal forces of a particular FE node in RFEM?

FAQ 003615 EN-US

First, you have to determine the position of the FE node. The easiest way is to use  - [Find by Number] (Figure 1).

Then, the found FE node can be defined by manual setting the result value (Figure 2).

The process is explained in the attached video.

1 - 10 of 42 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. ”