MODELLING MULTISTOREY TIMBER WALLS – PART 1
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SETTING UP
In the new model screen make sure you select N, m, C for units. Select the GRID ONLY option
The following dialogue box will pop up. Enter the following values. Change X direction spacing to match the width of
the wall, change Z direction spacing to match the height of the wall. Number of grid lines in the Z direction = number
of stories – 1. That is if you have 6 storey building, enter 7 grid lines.
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Now set the view up. Select “Set 2D view”
A dialogue box comes up. Selects X-Z plane, with Y=0 (see below), then click OK:
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Close all screens, except for X-Z Plane @ Y = 0, leaving a view like this:
SAVE THE PROJECT
Save to a folder of your choice, and call the file what you want::
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DEFINING THE MATERIALS
We are going to define timber materials. Let us use here the properties of VSG8 (say):
E = 8000 MPa and density is 500 kg/m3
Select Define and then Materials:
Then click Add New Material:
Apply the following settings EXACTLY, then click OK:
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DEFINING THE SECTION/S
We are going to define timber materials. Then carry out the following steps
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Type section name 50 x 150 and then select base material as VSG8. Then click SECTION DESIGNER:
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Now add a solid rectangle as follows:
Place the rectangle with the centre at the origin:
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Ensure the bottom right of the screen is set to N-m
Right click the section and set the properties as follows:
Then close the screen:
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Close the dialogue box, and then Add Copy of 50 x 150:
Set the name of the new section to “Floor” and then click Set Modifiers:
Close ALL the dialogue boxes.
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You should frequently save the project:
SET THE FRAME UP
Do the following to develop the frame:
Make sure your settings are exactly the same as below:
Draw the floors first, from the floor to the roof:
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Now draw the columns, with the sections EXACTLY as below:
Draw the columns one by one, with separate columns for each storey (ie a total of 12 columns for a six storey
building):
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Now assign the restraints, by selecting the bottom corners of the wall:
Then select the restraints menu:
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Use the settings below and then click OK:
The restraints will appear as below:
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ASSIGN FORCES AND MASSES
Let’s assume a mass of 4000 kg at the top floor and 9000 kg at the other levels (yours may be different):
First enable the programme to find midpoints:
Then click special joint, and add points to the midpoints of the floors (you do not need to do the one at ground
level):
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The points are thus assigned as below:
Now to ensure the points ‘glue’ to the members, select ALL the members (columns and floors):
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Select Automatic Frame Mesh:
Use the same settings as below:
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Now assign masses as follows:
Select the special points at the middle of the floors as follows:
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Then select masses:
Assign the masses as below (9000 kg is used for this example ---yours may be different):
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Then assign the mass at the roof (4000 kg used here – yours may be different):
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Now assign the vertical forces (I have used 3000 kN for the roof, and 6000 kN for the other levels):
For the floors, by selecting the points at the mid span of the floors (not the roof):
Enter -6000 for Force Global Z:
Now do the same as above, but set -3000 for the point at the midspan of the roof member.
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You can view the assigned loads as follows:
You should see the following:
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You can view the assigned masses as follows:
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SET UP THE LINKS TO REPRESENT THE FLOORS
Carry out the following steps:
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Apply the following settings and then click the button indicated:
Select Pivot Hysteresis type, then click OK, and OK again (we will apply the other settings later):
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You will end up back here:
Now in the same way as the previous steps, add links for Floor 2, 3, 4, 5, and 6 (or however many storeys you have).
After you have done this the dialogue box will appear as follows, then click OK to close the dialogue box and save the
project:
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Now add these links to the model as follows:
We start with the first floor:
Draw the floor 1 link between the midpoint of the ground floor and 1st floor as shown below. Then do the same for
the other levels:
The model now looks like this:
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