Creating Parametric and Fixed Profiles (for Hollow-core Slabs)

Not version-specific

Tekla Structures

Environment

Not environment-specific

General

A general problem with modeling hollow core slabs is that they’re easily created with too high accuracy, resulting in unnecessary memory drain. Too high accuracy would not generally cause a problem if there were only a few hollow core slabs in a model, but as that is usually not the case, the way a hollow core slab is created makes a big impact.

As the hollow cores themselves tend to have a more-or-less circular structure, too much emphasis is put on accurate depiction of the circular structure, needlessly making them resource hogs. This way of modeling results in an excessive amount of points for a single hollow core, and multiplying that with the amount of hollow cores in one slab – multiplied with the amount of slabs in the model – creates an astronomical amount of shape-defining points, most of which are unnecessary.

This manual demonstrates two ways to create a low-performance hollow core slab: one with which to create a parametric profile as well as one with which to create a fixed profile.

Parametric profiles are profiles that can be changed simply by changing their dimensional values, whereas fixed profiles have fixed dimensions which cannot (easily) be altered.

Both demonstrated methods use a custom-created cross section along with four-point chamfering for the hollow cores. Each hollow core has no more than four points defining their shape; emphasis is put on the quality of the points, not the quantity.

1. The Parametric Profile

1.1. Creation of a Parametric Profile
1.2. Using the parametric profile
1.3. Using the Profile in the model
1.4. Exporting and Importing Parametric Profiles

2. The Fixed Profile

2.1. Creation of a Fixed Profile
2.2. Using the Fixed Profile in the Model
2.3. Exporting and Importing Fixed Profiles

1. The Parametric Profile

Parametric profiles have adjustable dimensions, which can be changed.

There are two ways to crate parametric profiles: As a .clb file or using the Sketch Editor. In this article Sketch Editor is used. Note that starting from Tekla Structures 2019i the Sketch Editor is provided as a separate downloadable in Tekla Warehouse (Link). The tool needs to be installed in order to follow these instructions.

Instructions on how to create parametric profiles using .clb files can be found here: Create parametric profiles using .clb files.

1.1 Creation of a Parametric Profile

To start creating a parametric custom cross section, open the sketch editor from Modeling > Profiles > Define Cross Section in Sketch Editor

The Sketch Editor is opened along with the Sketch Browser and Variables window.

Figure 1.1 Sketch editor

Sketching the cross section

1. Click the Sketch Polyline icon.

2. Sketch the example hollow core slab somewhat along the lines of the one seen in figure 1.2 and end sketching by clicking the middle mouse button. Each inner square is sketched in a similar way.

The yellow circles represent chamfer points in the sketch editor. These will help us define the circular hollow cores inside the slab later on.

Figure 1.2 Hollow core cross-section sketch

The cross section does not have to be an exact representation yet. A general outline will more than suffice at this point.

1. Click the Add coincident constraint icon.

2. Pick the ends of the lines one by one to connect them and create chamfer points.

Figure 1.3 Coincident constraint

3. Add coincident constraints to the inner rectangles as well.

Force Horizontal and Vertical lines

We will now force the singular lines to follow a more sensible, orthogonal representation.

1. Click the Add horizontal constraint icon.

2. Click on all the lines you want to be horizontal, thus making them horizontal.

3. Click on the Add vertical constraint icon.

4. Click on all the lines you want to be vertical.

The end result should look something similar to the example shown below in figure 1.4.

Figure 1.4 Horizontal and vertical constraints added

Sketches inside sketched profiles create holes. Any number and shape of holes can be created inside the custom profile using the Sketch editor.
Note: the maximum number of points that can be created is 99.

Adding Vertical Dimension Constraints

We will now define dimension parameters for the cross section. Dimensions can be user-definable, tied to user-definable parameters or set dimensions which cannot be altered.

1. Click the Sketch vertical distance icon.

2. Select two points (shown in red) and pick a position for the dimension line. A dimension is added and a modifiable variable is added to the Variables window.

Figure 1.5 Adding dimensions

3. Add dimensions for hollow core vertical spacing as shown in figure 1.6. NOTE! Bind all of these dimensions to the same chamfer point, in this case the upper left corner of the slab and each hole!

Figure 1.6 Vertical dimensioning points

4. Change the Formulas of parameters h3-h7 to =h2 in the Variables window. This will align the hollow cores vertically and create a uniform, vertical concrete thickness.

Figure 1.7 Value added

5. Add vertical dimensions to the hollow cores in order to define their height.

Figure 1.8 Hollow core height

6. Set the Formula of parameters h9-h13 to =h8 in order for the hollow cores to have equal height.

Figure 1.9 Height unity

Be careful to not add too many dimensions to the profile or the constraints will work against each other.

Adding Horizontal Dimension Constraints

Now that the vertical constraints have been added, we will continue to add the horizontal constraints.

1. Click the Sketch horizontal distance icon.

2. Add a width dimension.

Figure 1.10 Width dimension

3. Add dimensions to define the hollow core spacing as shown in figure 1.11.

Figure 1.11 Hollow core spacing

4. Set the Formula of parameters b2-b7 to =h2 in the Variables window. The concrete thickness will now follow the value given to h2 and will later be uniform on all sides as well as between the hollow cores.

Figure 2.12 Value added

5. Add dimensions to define the hollow core widths.

Figure 1.13 Hollow core width

6. Change the Formula of parameters b8 to b13 to =h8. This scales the width of the hollow cores according to parameter h8, making them perfectly square.

Figure 1.14 Hollow Core Width Parameterization

When creating circular hollow cores using chamfering, it is important that the unchamfered hollow cores are perfectly square – otherwise, the chamfering will not create perfect circles.

Creating User-definable and tied parameters

Now that the hollow core slab has defined dimension parameters, we can begin altering them to use more acceptable dimensions.

We want to alter the slab to have a height of 200mm, a width of 1100mm and a standard thickness of 20mm, meaning that the core diameter would be 160mm. We also want to be able to later change the width and thickness so that the height and hollow core diameters will follow suit and keep the slab uniform.

Figure 1.15 Example outcome

1. Set the Formula of b1 to 1100 and set its Visibility to Show. This allows us to later manually change the value of the width. (see figure 1.10)

2. Set the Formula of h2 to 20 and set its Visibility to Show. Write Concrete thickness into the Label in dialog box field.

Figure 1.16 Thickness labeling

3. h8 defines the length of the sides of the hollow core rectangles. Change the Formula of h8 to =(b1-7*h2)/6. This is the length of one hollow core side in relation to the width of the whole slab. All hollow cores will update their height and width accordingly.

Figure 1.17 Variables h8, h2 and b1

Note that (b1-7*h2)/6 = 160 mm, our preferred hollow core diameter.

The values of dimensions referencing to other dimensions may not always update themselves automatically. In this case, rewriting the Formula for the dimension or clicking the cell where the formula is written should take care of the problem.

4. Change the Formula of h1 to =h8+2*h2. The height of the slab will now be calculated according to the assigned concrete thickness and the hollow core diameters.

The end result should look similar to figure 1.18.

Figure 1.18 Dimensioning end results

Chamfering

Chamfering rectangular cores in the sketch editor is one of the most efficient ways to create circular cores into hollow core slabs. Because the circular core is defined by no more than four points – the four points of the rectangle – the core does not require nearly as much processing power as other methods requiring several more points.

1. Double-click on a corner chamfer point of a core. The Chamfer properties window will pop up.

Figure 1.19 Chamfer properties

2. Change the properties to those shown in figure 1.19 and press Modify.

3. Modify the remaining core corner points.

The chamfer value must be half the length of one side of the square in order to create a perfect circle. The height and width must also be the same in order to properly define the circle diameter.

Image

Figure 1.20 Chamfering end result

Currently, the chamfers are not bound to any dimension: even if the hollow cores themselves will react to any size alterations done to the slab, the size of the chamfers will remain the same. The chamfers must therefore be bound in a similar way as the dimensions in order to be able to resize themselves and remain as perfect circles.

1. Open the Component Objects through the Sketch Browser.

Figure 1.21 Sketch Browser

2. Select a core Chamfer constraint in the Sketch Browser as shown in figure 1.22. Note that the selected chamfer constraint is highlighted in the Sketch Editor, making it easier to locate the correct one.

Figure 1.22 Chamfer constraint location

3. Right click on the Chamfer X setting and click Add equation.

4. Add the equation =h8/2, as this equals half the core diameter. The chamfer size will now change according to alterations in core diameter and remain as a perfect circle.

Figure 1.23 Chamfer X parameterization

5. Follow steps 2-4 to bind the chamfer x values of all other core chamfer points accordingly.

6. Click the Save Sketch icon to name and save the profile.

7. Click the Close Sketch icon to close the sketch editor.

1.2 Using the Parametric Profile

Verifying the Existence of the Custom Profile

The sketched profile is automatically added to the main Profile Catalog once it has been created in or imported to a model. To verify the access and existence of the sketched profile go to Modeling > Profiles > Profile Catalog…

Custom profiles are categorized into the Others section of the Profile Catalog.

Figure 1.24 Profile Catalog

1.3 Using the Profile in the Model

The custom hollow core slab profile cannot actually be drawn with the concrete slab functionality since it is not possible to define a specific profile shape for a slab, only a specific thickness.

1. Double-click on the Create concrete beam icon.

2. Click the Select… button next to the Shape field to open the Profile Catalog.

Figure 1.25 Selecting custom profile

3. Select your custom profile in the Others section.

4. Alter the Width and Concrete thickness if needed.

Figure 1.26 Custom component dimensions

Notice that the fields are the same ones whose Visibility was set to Show in the Sketch Editor. The descriptions added in the Sketch Editor are visible as well, as are the current measurements for the user-definable parameters.

5. Once you’ve done any necessary alterations, click Apply and OK.

Figure 1.27 Apply

6. In the Concrete Beam Properties window, click Apply. Drawing a beam now produces a hollow core slab according to your custom cross-section.

1.4 Exporting and Importing Parametric Profiles

There may arise a need to use a custom profile in several different projects, or you may want to share your custom profile with another party. It is possible to export custom profiles from one model or environment to another.

Unlike custom profiles made using other methods, sketched profiles cannot be conveniently exported and imported via the Profile Catalog. Instead, they are exported and imported through the Component Catalog.

Exporting a sketched profile

1. Open the Component Catalog through Detailing > Component > Component Catalog…, by pressing Ctrl + F or by clicking the toolbar icon.

2. In the profile drop-down box, select Sketched Profiles to find the recently created HCS profile.

3. Right-click on your sketched profile and click Export.

Figure 1.29 Exporting Sketched Profile

4. Select a file location for the export file and name the export file.

5. Click OK.

Importing a sketched profileinto another model or environment

1. Open the other model/environment.

2. Open the Component Catalog.

3. Right-click anywhere on the Component Catalog background and click Import….

4. In the Import Components window, browse for the file location of your exported profile.

5. Select the profile and click OK.

The sketched profile can now be found with the Sketched profiles filter in the Component Catalog.

2. The Fixed Profile

2.1 Creation of a Fixed Profile

Creating a fixed custom profile is a somewhat different working progress in comparison to creating a parametric custom profile.

Fixed cross sections can be defined either with a polygon or with a contour plate. For the sake of workability we will be creating the fixed-measurement hollow core slab profile with a contour plate.

Chamfering square hollow cores into circular ones is one of the least demanding methods of hollow core slab creation regarding system performance. As such, we will first create a fixed profile with square hollow cores, which we will later on modify and chamfer into circular cores.

Creating Necessary Construction Lines

Creation of a suitable hollow core slab using a contour plate requires exact dimensions. For the sake of consistency, we will create a hollow core slab profile with the same measurements used with the parametric profile: the profile will have a height of 200 mm, a width of 1100 mm and a standard thickness of 20 mm, with six hollow cores, each with a diameter width of 160 mm. Unchamfered, the contour plate will eventually end up looking like the one presented below.

Figure 2.1 Example Contour Plate Profile

1. First off, press Ctrl + P. Working in a 2D view considerably reduces incorrect snapping.

2. Click Modeling > Add Construction Line or click the Construction Line icon in the toolbar.

3. Create construction lines as shown in figure 2.2 according to the measurements specified above.

Figure 2.2 Construction lines with reference dimensions

Creating the Contour Plate

We need to create one large contour plate along the outer construction lines. This contour plate serves as the actual profile template. Once the contour plate has been created, we will use the inner construction lines to facilitate the cutting out of the hollow cores.

1. First, click the Create Contour Plate icon.

2. Beginning from the top left corner, create the contour plate by picking the corner points according to the order shown.

Figure 2.3 Corner point order

Cutting out Hollow Core Polygons

The hollow cores are cut out using the Cut part with polygon command. This allows simple, square, fixed-dimension hollow cores which we can later on chamfer into circular hollow cores, which require only minimal system resources.

It is important to keep in mind that, as when creating parameterized profiles, the maximum number of points that can used to create a fixed-dimension profile is 99.

1. Click the Cut part with polygon icon.

2. Cut out the hollow cores using the inner construction lines, making sure to pick the polygon corners in the order shown in figure 2.4.

The hollow cores measure 160 mm by 160 mm.

Figure 2.4 Polygon cut corner picking order.

Keeping the order that the contour plate and polygon cut corners are picked in constant is extremely helpful later on when the necessary corner chamfers are created.

3. When performing the cutting, make sure to cut the cores out in a uniform manner to more easily facilitate alterations on the correct corner points.

Figure 2.5 Cutting out hollow cores

Your contour plate should now look like the one demonstrated earlier.

Figure 2.6 Finished contour plate

Turning the contour plate into a fixed profile

Now that the contour plate has been finished, we can readily turn it into a profile cross section.

1. Go to Modeling > Profiles and click Define Cross Sections Using Plates...

2. Go to the Parameters tab and fill in a Section Name and Profile Name. Set the rest of the empty fields according to the figure shown below and the Coordination system to Use global xy-plane.

Figure 2.7 Parameters

3. Click Apply.

4. Pick the contour plate. An example beam using the newly created profile will appear. More importantly, the new profile has now been added to the Profile catalog under the Others section as a User-defined, fixed-measurement profile.

Adding Chamfers to the Profile

As with parametric profiles created with the Sketch Editor, the most resource-effective way to create circular hollow cores into a hollow core slab is by first creating square hollow cores after which these square cores are chamfered. This way, each circular hollow core requires no more than four points of reference and thus very few calculations from the system.

1. Go to Modeling > Profiles > Edit Polygon Cross Section...

2. Select your cross section in the list of available profiles in the Modify Cross Section window.

Figure 2.8 Modify Cross Section

Notice the drop-down box next to the Number: title. The numbers represent the creation order of all the corner points in the profile.

Figure 2.9 Corner point numbers

The main numbers (in this case 1, 2, 3 and 4) denote the outer corners of the profile, whereas the larger numbers (*00*) represent the corners of the hollow core cutouts. Because they are numbered in creation order, it is usually important to keep the creation order uniform throughout for personal clarity and ease of workability.

3. Select corner number 1001. Change the x: value to 80 (as this is half of the hollow core diameter) and the Chamfer: type to the one shown below. Press Update.

The chamfer value must be half the length of one side of the square in order to create a perfect circle. The height and width must also be the same in order to properly define the circle diameter. Thus, as the height and width are both 160 mm, the chamfer value is set to 80 mm

Figure 2.10 Chamfering corners

4. Working your way through the rest of the four-digit numbers, change the properties of all the hollow core corners according to figure 2.10.

5. Once you’ve gone through all of the necessary corner points, click OK.

6. When prompted, click OK to save the changes to the model folder.

The hollow core slab profile is now complete and ready for use.

2.2 Using the Fixed Profile in the Model

As with a parametric profile, a fixed hollow core slab profile cannot be actually drawn with the Concrete slab option (as slabs do not actually use profiles), but must instead be created as a concrete beam.

7. Double-click on the Create concrete beam icon.

8. Click the Select… button next to the Shape field to open the Profile Catalog.

Figure 2.11 Selecting the custom, fixed-measure profile

9. Select your custom profile in the Others section.

Figure 2.12 Profile catalog

10. Click Apply and OK

11. In the Concrete Beam Properties window, alter the Material type if needed and click Apply. Drawing a beam now produces a hollow core slab according to your custom cross-section.

At this point, you may notice that some of the corners have been left unchamfered.

Image

In this case, simply go back to Modeling > Profiles > Edit Polygon Cross Section... and change the chamfering settings of the appropriate corner point.

2.3 Exporting and Importing Fixed Profiles

Like parametric profiles, fixed profiles can be exported from and imported to other models and environments. Exporting single custom profiles removes the need to re-create them again and again.

1. Open the Profile Catalog through Modeling > Profiles > Profile Catalog…

2. Right-click on your custom profile and click Export Profile.

Figure 2.14 Export Profile

3. Select a file location for the export file and name the export profile.

4. Click OK.

5. The profile is now located at the specified file location as a .lis-file, which can be imported to other models/environments.

Importing fixed profiles into another model or environment

1. Open the other model/environment.

2. Open the Profile Catalog.

3. Click the Import… button in the lower lefthand corner.

Figure 2.15 Import…

4. In the Import Profile Catalog window, browse for the file location of your exported profile, stored as a .lis-file.

5. Select the profile and click OK.

The fixed profile will now appear in the same profile branch as in its original model and can now be used.