Module "Compression perpendicular to grain"

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The input is divided into:

definitions of the cross section
definitions of the plate dimensions
input of the loads
type of load configuration
calculation options

An option for a quick control of the input data is offered by a graphical representation shown on the right side.

The cross section can be defined by the user or by choosing a typical cross section of a proprietary CLT product. There is also the possibility to save own CLT cross sections in a library. The elements are subdivided by the number of layers.

If a user-defined cross section is entered, the thickness and orientation of each layer can be changed. Furthermore, the material can be changed for all layers. The thickness of each layer has to be within the range of 6.0 mm to 45 mm. In the case of proprietary CLT products, the strength class of lumber and the orientation can be changed. If the orientation is changed, the whole cross section is rotated.

The width of the CLT plate strips can be also defined in this field. The default value is set to 1 m. The thickness of the CLT plate is calculated automatically based on the thickness of the single layers.

The ratio of board thickness to board width can also be changed here. The default setting is 1:4.

My CLT cross sections

By clicking the button the current cross section can be stored in the library and be retrieved by selecting "My CLT cross sections" later on.

The library can be displayed with the button .

The edit mode can be entered by clicking on . Currently, only the name of the stored cross section can be changed.
With the changes are saved.
With the chosen cross section in the sidebar can be removed from the library.
With cross sections from a csv file can be imported.
With the cross sections from the library can be exported to a csv file.

Syntax of the csv file

name;number of layers n;layer thickness in [m] t₁ to t_n;orientation of the layers o₁ to o_n (0 or 90);name of material

Example:
Test layup;5;0.03;0.02;0.02;0.02;0.03;90;0;90;0;90;GL24h*

My materials

With the button the material library can be displayed.

With the edit mode can be entered.
With the changes are saved.
With the chosen material in the sidebar can be removed from the library.
With materials from a csv file can be imported.
With the materials from the library can be exported to a csv file.

Syntax of the csv file

1. row: description of the parameters
2. row: units of the parameters
3. row: value
delimiter: ";"

Example:
Name;f_m,k;f_t,0,k;f_t,90,k;f_c,k;f_c,90,k;f_v,k;f_r,k;E_0;E_0,05;E_90;G;G_r;rho_k;rho_mean;f_v,k,IP;f_T,k;f_m,k,IP
;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;N/mm2;kg/m3;kg/m3;N/mm2;N/mm2;N/mm2
Mat 1;24;16.5;0.5;24;2.7;3;1.25;11600;9667;0;720;72;380;500;5.5;2.5;21

The user-defined materials are then displayed in the material selection list.

Optimization of layup

Use the button to display the window for layup optimization.

With the help of this tool, the possible layups can be determined for the given system and load situation. The optimization can be restricted with regard to producers, number of layers or by means of limits for the panel thickness. Furthermore, outer cross layers or double layers can be included or excluded. With the option "Vibration verification according to EN" the base document is included in the vibration check or not.

With the buttons "Start" and "Stop" the calculation is controlled. Please be patient, depending on the selected parameter the calculation may take a little longer.

The possible setups are then displayed in the table and the selected setup can be transferred to the main window by clicking the "Choose the selected cross section" button.

Cross section · 2017/11/14 17:11

The plate is specified with its dimensions in x and y direction. The plate length is defined with dimension in x direction and the plate width with dimension in y direction.

In addition to plate dimensions, the analysis also considers the way the lamellas are joined into individual layers. Regarding to the joining of the outer layers, one should differ:

side gluing of lamellas,
assembly without adhesive where lamellas are placed side by side without the sheduled gaps or the expected occurence of cracks and
possible occurence of gaps or cracks wider than 1 mm.

The applied force F_c,90 (design value) in [N], as well as the design factors can be specified here.

The load situation is described by specifying the load introduction above and below. Thereby, one can define if the load is even applied, and if so, if it is applied locally or continuously (over entire surface).

If the load is applied locally, it needs to be defined by entering the dimensions of the load surface (length l_1,2 in direction x and width w_1,2 in direction y) and the position. The position is defined as the distance between the center of a load surface and the origin of the coordinate system (lower left corner of the plate). Currently, centers of the top and the bottom load surface are coupled and cannot be moved relative to each other.

In the calculation options, the load distribution angles for longitudinal layers α₀ and cross layers α₉₀ can be changed, and for one-sided load introduction, it can be specified, in which depth (= k_ls ⋅ t_CLT) the effective area is to be determined.

The minimum load introduction area A_c,min describes the reference area in order to get the effective area A_ef,max by multiplying with the factor k_c,90. For different load introduction areas on each side it is the intersection of these two areas. The effective area A_ef,max is described by l_ef and w_ef in depth z.

The utilisation ratio for compression perpendicular to grain is indicated by η_c,90 in [%].

The following figure shows the distribution of the effective area A_ef,max over the cross section (red line) as well as the assumed load distribution (blue line).

Compression perpendicular to grain - Verification

Model for the determination of the kc,90 factor

Module "Compression perpendicular to grain"

Input data

Cross-section

My CLT cross sections

My materials

Optimization of layup

Plate dimensions and gap execution

Load data and design factors

Load configuration

Calculation options

Results and Output

Implemented calculation methods