The majority of the steel structure connections are the bolted joints. The “Bolts” tool allows designing both bolts objects as well as bolt holes.
To create a bolted joint, let’s firstly set up the objects to be
Set up two plates with dimensions of 130 x 300 and thickness of 16 mm.
The algorithm for creating a bolted joint:
If the bolts are displayed in a simplified way as it is shown in the above picture, then it is possible to display them exactly by selecting the bolts, and enabling in the right-click menu the ”Show with Exact lines” tab.
The point with coordinates at (0;0;0) is the reference point for allocating
Depending on the default settings, bolted joint can be aligned as it is
Do not consider this an error. It is an adjustable bolted joint geometry layout. It is commonly known from the geometry course that determining a plane requires indicating 3 points, not two, as we did when creating the bolted connections. Thus the above case concerns the fact that the 3rd point of the plane is not indicated.
There is only a segment around which the bolts rotate. Switching the alignment of the bolts is done at the “Bolt Properties” window by configuring the “Rotation” parameter to one of the available options, each of them rotating the bolted joint at 90 degrees (0,90,180, 270).
Exercise by yourself adjusting the layout of the bolted joint as required.
Also, it is possible to specify a complementary rotation angle by writing it in the adjacent to “Rotation” field box. Rotate the bolted joint at the angle of 45 degrees.
Restore the angle value to 0.
Let’s investigate the “Position on plane” parameter. Write in the respective box the value of 100mm. The bolted connection group has shifted by the Y-axis at 100 mm.
It is possible to introduce negative values of the parameters as well, thus shifting the group of bolts to the opposite direction. Try this out by indicating a negative value at the “Position on plane” field.
Bring all values to 0.
The “Position at depth” parameter stands for the bolts' displacement along the Z-axis, without influencing their length, as TS automatically sets up the length of the bolts.
Though, specifying the major values into the field causes an error as
Thus we recommend not using the “Position at depth” parameter
Restore all the values to 0 as is shown below. As a result, you will get
The quantity of bolts.
It is important to mention that the “Bolt dist X” and “Bolt dist Y” fields are specifying not the bolts quantities but the distances between the bolts by the axes X and Y. Thus writing into the fields 0 values generates one single bolt, as 0 value stands for the distance to the next bolt.
Create one more bolt located at the X-axis at the distance of 55 mm from
Principles for introducing data into these fields are similar to those of the “Grid Properties” which we examined in the previous chapters.
Write in the value of 4*55. Note that the total quantity of bolts
Specifying the inter bolts distances by the Y-axis makes the X-axis the
Write into the “Bolt dist Y” field the value of 60mm.
Introducing an additional value into the Y-axis field creates an extra
Thus creating a bolted joint stands for selecting its right X-axis direction in the way the first and the second points are to be allocated at the symmetry axis of the joint.
Upon the exercise completion, restore the field values to 0.
The “Offset from” field
When the values of the fields are equal to 0, there is only one bolt allocated at the edge of the plate at the origin point of the X-axis. In practice, bolt holes shall not be located right at an edge of an object. Thus completing the “Offset from” field ends up with this issue by specifying the starting and the endpoint offsets separately.
Set up the starting point for the X-axis at 40 mm.
As you can see, the bolt was shifted at 40 mm, though its system coordinate
Setting up the same value to the endpoint implies no changes to the bolted joint, as it describes the X-axis direction and the distance between the starting and the endpoint is of no importance.
To avoid any confusion, let’s leave the values of the endpoints
Indicate the “Bolt dist X” value of “4*55”, thus
Specifying a larger quantity of bolts keeps on inserting bolts in the
Now set up the endpoint offset value at 40 mm by the Y-axis, leaving the
Compare your results to those presented in the above picture: the endpoint of the bolt's string was displaced at 40 mm. Bringing the Y-axis offset starting value to 40mm.
Compare your results to those presented in the above picture: all the
Make all values of the Y-axis parameters null to test out the Z-axis parameters.
Now write in the Z-axis starting point value of 100mm. The group of bolts shifted vertically by the Z-axis. There is no particular practical use of such shifting by the Z-axis.
Thus we have examined all the offset options. Let’s generalize the main principles: the X-axis direction is defined at the stage of creating a bolted joint, but the other axes' directions are determined by the left-hand rule.
Open the “Bolts properties” dialog window and set up the values of the parameters as shown in the picture below: Dx=40, bolt distance by X equals 4*55 mm, bolt distance by Y equals 60mm, other values being 0.
The “Bolt Standard” field
The regulatory standards vary from country to country thus the lists of standards are different and are simultaneously installed along with the TS software and the environment package.
The "Size" field is correlated to the “Bolt standard” field. Choosing a particular standard specifies the diameter of the bolt.
Exercise toggling with the various standards options and simultaneously checking on the associated bolts size list. Make sure that the bolts size lists vary depending on the standard in use.
The “Bolt type” field specifies just 2 characteristics of a bolt, which are: "site" and "workshop". Choosing one of these options brings no apparent difference to the model. The only case when the difference can be tracked is when creating assembly drawings. Site bolt type connects parts into an assembly that is to be installed at the worksite. This is the most frequently used type of bolt. The workshop bolt type is used extremely rarely and is installed at the plant.
The “Thread in material” field defines the bolted joint length in the way that its thread hits into the joinable parts (plates) or is strictly standing about the joinable parts. By default, threads reside in the joinable parts. Let's go through all possible threads set-up options:
There is a default option for allowing thread in material. Thread in material does not affect the bolted joint bearing capacity, as the latter is calculated taking into account the thread engagement length.
When avoiding using bolts with thread in material, the TS enlarges the length of the bolts and adds numerous washers to assure the nut’s screw-in. This way represents a sufficient material cost overrun. In the above picture see the maximum bolt grip length marked with green.
Unless otherwise stated by the contractor, do not hesitate to use bolts with thread in material. Let’s test out customizing various bolts options.
Copying plates with bolted joints at 150 mm aside and indicate for the first group prohibition against using bolts with thread in material, and vice versa.
Pay attention to the prohibition against using bolts with thread in material: the bolts created are of a bigger length and have an additional washer (see marked in red).
The “Cut length” field
It is practical to use this tool in case there are several part’s bounds to get joined. For example, an I-beam has upper and bottom flanges, which can be connected, thus specifying the cut length value may determine to connect or not the flanges of the object. Create an I-beam as it is shown below, where:
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A - The cut length is indicated in the respective field of the "Bolt Properties" window. In other words, it is also the interval for sourcing the faces of the parts. Note that the TS scans the area above and beyond the I-beam flange, thus the cut length value is divided into two.
If it is of high importance to specify a constrained value of the bolt, then indicate it with the “-” symbol preceding it. If consciously indicating a deficient cut length value, then it will not connect the I-beam faces and will work at only one flange. Indicating a consciously larger cut length value joins both flanges of the I-beam. Specifying a negative value (e.g. -150) creates a bolt of a forced length parameter value. The “-” symbol is just a markup in this case.
B - the starting point |
Create similar sets of bolted joints with different values of the cut
The “Extra length” field specifies the length extension of the thread at the end of the nut, though its value is not a certain one. So far as we do not specify the exact length of the bolt, thus we can not indicate the exact thread extension value.
The bolt length is automatically picked out of the material catalogue as the maximum fitting one. The material (bolts) catalogue is described by a limited bolts length set, where the most frequently used bolts length values are divisible by 5 mm. (e.g. 80,85,90,95,100..).
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A bolt’s length is composed of the following:
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E.g., if we sum up the above values and obtain 95.2 mm, then we conclude that there are no bolts of such length, thus TS will automatically pick up the appropriate option from the material list, which is 100 mm length bolt. Thus the bolt will have the thread extension, deductible as follows: 100-95.2 = 4.8 mm.
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Correspondence between the thickness of the part and the thread extension value. |
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The total of the thicknesses except of thread extension |
a+b+c+d+e+f |
95.2 |
96.2 |
97.2 |
98.2 |
99.2 |
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Extra length |
g |
0 |
0 |
0 |
0 |
0 |
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TS bolt length |
L |
100 |
100 |
100 |
100 |
100 |
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Actual thread extension |
L-
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4.8 |
3.8 |
2.8 |
1.8 |
0.8 |
Thus setting up the extra length value at 0 and taking account of the total of the metalware thicknesses we get a scatter of actual thread extensions from 0 to 5 mm (where 5 is the bolts size step). If setting up the extra value at 1, the scatter of the actual thread extensions will vary from 1 to 6 mm, excluding 6. Thus we specify to the "Extra length" field not the real thread extension value but its minimum value.
The “Shape” field allows configuring the alignment of the bolts. There are available the following alignment types:
Till now, we were aligning the bolted joints in an "Array" way.
The "Shape" field - “Circle”
Create a square plate with a side length of 200 mm and a thickness of
Go to the view plane by activating the Ctrl+P hotkey combination. Using the construction geometry, create two lines intersecting at the center of the plate square shape.
By using chamfers, modify the plates to circle-shaped objects: select the plates, by holding on the “Alt” key, select their points, make a double-click on a point, and simultaneously hold the “Shift” key pressed, and go to the “Chamfer properties” window. Specify the chamfer type as “Arc point” and press the “Modify” button.
Create a column with the round pipe profile type “RO152.4*5.0-MSH”.
Create default views of the part referring to the below:
Proceed to “Fit the work area to selected parts”for the
Go to the "Side view" and copy the round pipe as shown in the
Get back to the view plane and rotate it to 3D, switch the display mode
Go to the “Bolt properties” window and set up the "Bolt group shape" to “Circle”. Specify the number of the bolts as 6 units, and indicate the circle diameter of 210 mm.
The bolts are arranged along the circle. Let’s set up the number of bolts at 12.
Creating such a bolts distribution is not possible by using the "Array"
Bolt group shape "By line” aligns bolts according to the X and Y axes coordinates indicated for each bolt separately.
To try out the “By line” type, create a square plate with
Go to the view plane by using the Ctrl+P key combination and create two
Similar to the previous case, create a pipe of the square profile type
Enable the “Bolts” tool and create an "Array" bolts
Configure the distances between bolts as “2*70” and the starting point offset value as''30 ``. In terms of construction, there shall be no bolts at the plate center, as it is not possible to be screwed in the place. Thus bolt group shape “By line” comes out as a very convenient option, allowing setting up each bolt coordinates, and skipping on the center bolt coordinates.
First and foremost let's find out the coordinates of the "Array" bolts group to be further specified "By line". Let’s trace the imaginary X-axis and Y-axis perpendicular to it.
Accordingly, each bolt coordinates can be specified as follows:
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Bolt number |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
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X-position |
30 |
100 |
170 |
30 |
170 |
30 |
100 |
170 |
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Y-position |
70 |
70 |
70 |
0 |
0 |
-70 |
-70 |
-70 |
Switch the bolts group shape to “By line” and restore all parameter values to 0, thus creating a single bolt with coordinates at (0,0) point.
Now write in the bolts coordinates by X and Y as mentioned in the above
Tekla Structures v21.1 |
Tekla Structures v2021 |
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The present TS version does not support specifying the bolt group shape “By line” by writing in a single coordinate. Using this function is available when indicating 2 and more coordinates, e.g. (30;70) and (100;70). |
Further insert the second bolt coordinates by space.
Tekla Structures v21.1 |
Tekla Structures v2021 |
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The present TS version does not support specifying the bolt group shape “By line” by writing in a single coordinate. Using this function is available when indicating 2 and more coordinates, e.g. (30;70) and (100;70). |
Note that the TS automatically simplifies the coordinate line when identical
Write in all the bolts coordinates for the rest of the table.
As the result there are the following value lines: for X-axis “ 30.00 100.00 170.00 30.00 170.00 30.00 100.00 170.00 ”, for Y-axis: “ 3*-70.000 2*0.000 3*70.000 ”
Thus using the "By line" shape, it is possible to create a bolts
As an alternative to this method, you may follow another scheme. Copy the bolted connection created at 300 mm downwards, delete the bolted connection and create a new one with the bolt group shape parameter configured as “Array”. Refer to the below:
Now, the bolt located at the square plate midpoint is to be deleted. Proceed to delete it by enabling the “Select single bolt” tool and pressing the “Delete” button.
Do not forget to restore the "Select all" tool to the active position, otherwise, it will not be possible to select any object in the model. Make a double-click at any bolted connection element and go to the “Bolt properties” window. After deleting the bolt, TS automatically switched the bolted group shape type to “By list” and created the string of coordinates.
The “Tolerance” field allows increasing the bolt hole diameter accounting for the bolt diameter. In practice, the 20 mm diameter bolt does not match the hole of the same diameter, the reason being the unavoidable production inaccuracies of the metalwares.
That is why usually for a 20 mm diameter bolt the hole diameter of 22-23 is prepared, where 2-3 mm is the tolerance that simplifies the installation process. Indicating the value of 2 mm into the “Tolerance” field specifies the hole diameter of 20+2=22 mm ( where the “Tolerance” field value sums up with the “Bolt size” field value).
The requisite tolerance values are to be verified according to your
The “Bolt Assembly” section specifies the elements of the bolted connection.
Let’s, first of all, clear up the metalware types and differences between them. Depending on your country’s regulations and standards and contractor’s requirements, the bolt assembly composition may vary. There are 2 basic types of bolts:
The main difference between these bolts types is that in frictional bolt joint connection bolts are due to a preloaded tension force, thus ensuring frictional dragging of the joinable elements. High-strength friction bolted joints are not self-loosening thus the bolt assembly kit does not require a lock washer or a second nut.
The standard bolts type is used for building up the joints with no preloaded tension force in them, but due to various vibrations, temperature variations, and other factors, the nut torque value decreases up to the nut completely unscrewing off the bolt. There are 2 basic ways to prevent such cases:
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Bolts loosening preventive options:
А) Using a lock washer. B) Using concomitantly 2 nuts . С) Using high-strength friction grip bolts |
You can configure the bolted joint assembly according to the project requirements.
Let’s create the A scheme bolted joint (refer to the above picture
The bolt assembly section is to be specified as follows:
Tekla Structures v21.1 |
Tekla Structures v2021 |
Configuration |
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Verify the bolt assembly configurations using the below picture:
Let’s create the B-scheme bolted joint. It is the most frequently
Let’s create the C-scheme bolted joint suitable only for friction
Removing the bolt check-mark creates just a bolt hole, with no metalwares
The “Hole type” field configures the bolt hole shape and its dimensions in case there is a grooving or an oversize. It is possible to execute configuring the bolt holes dimensions separately or for the whole bolt group at once.
In the majority of cases bolts are connecting only two parts:
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But in several cases, bolts may join 3 parts same time. As an example, these are twin profiles, double butt straps, or connections with intercalated plates.
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Connections with over 3 pcs. joinable parts are almost not used in practice, though the Tekla Structures package provides holes adjustment for up to 5 pcs. joinable parts, this being more than sufficient.
Create a plate with dimensions of 130*130 and a thickness of 16mm. Copy the plate vertically 5 times. Create a bolt connection by selecting all 5 plates as the joinable parts. Make sure that the cut length value is not less than 200mm, otherwise, the bolt length will not be a sufficient one to join all the parts.
As you can see in the above picture, each joinable part has got its bolt
Modify the tolerance value by setting it up at 50 to see the bolted joint
Note that the bolt holes have been widened uniformly at each part level.
Restore the tolerance value to 3mm.
In the above picture, you can see markings at the bolt body framed with red, indicating that the dimensions of the bolts can be configured separately for each of them. Below schematically in blue are drawn the joinable parts, their sequence as you have selected them when creating the bolted joint.
Tekla Structures v21.1 |
Tekla Structures v2021 |
Configuration |
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Enable the check-mark referring to the first part. After activating at
Specify the hole type as “Slotted” and write in the
Note that only the hole, which checkmark is active, has changed its shape.
Now create a grooving at the Y-axis, and restore to 0 the X-axis field value. In this way the slotted hole will get aligned by the Y-axis.
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Tekla Structures v21.1 |
Tekla Structures v2021 |
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Enable the check-marks of the other joinable parts as well.
The "Slotted hole" type is very useful for compensating inaccuracies when installing the structures. In the current case study, you can see that all the holes are compensating the inaccuracies only by the Y-axis.
Unilateral compensation is of no sense , that is why it is recommended
In the TS there is a special field called “Rotate slots”.
Now you can see that each next slotted hole is perpendicular to the previous one. Switch the “Rotate slots” field value to “Even”. The slotted holes are still perpendicular to each other, except for the orientation of the slotted hole: by Y-axis, or by X-axis.
Configure only a couple slotted holes. Remove the checkmarks for the referent
Keep the checkmarks for the joinable parts 2 and 3.
The “Hole type” field allows creating a slotted bolt hole or adjusts the round bolt hole diameter for the joinable parts with a check mark. When setting up the “Hole type” field value at “Oversized” the TS will automatically start increasing the hole diameter to the oversize value indicated. Let’s set up the oversize value at 50mm, thus the bolts hole real dimensions will become a sum of the following values: bolt diameter + cut length value + oversize value, and the real hole dimensions will be 20+3+50=73mm.
How to change the bolted joint parts and for which purpose we have not discussed yet, as first of all we should examine the sequence for selecting joinable parts of a bolt connection. The sequence for selecting parts is very important, when creating a bolted joint, as this information is reflected in the statements when distributing the bolts by the assemblies and when copying the bolts, as it is essential to know to which parts exactly they refer.
Let’s get straight to the point and examine the procedure of copying
Even though the bolt itself was not selected before copying it was automatically
Now, copy only four plates without selecting the bolted joint.
Now, the bolt was not copied, as accordingly to the initial object, it refers to all five joinable parts. Thus deleting or not selecting all the joinable parts of a bolted connection does not replicate the bolt in the copied objects. Let’s delete one of the five plates of a bolted joint. By proceeding this way, note that the bolt got deleted as well. It is avery important property of the bolted joints.
Summarizing the above, it is not possible to copy a bolt to a new joinable part set, as it requires creating a new bolted connection with different joinable parts (plates).
When creating a bolted joint, it is essential to indicate all the joinable parts to be threaded by a bolt. Let’s simulate a consciously erroneous situation when not all the joinable parts of a bolted connection were selected, for example, only the upper and the lower plates.
In outward appearance, it looks as if there is no difference between the models, but it is not true, as threading through the parts, which were not selected, has not created any holes in them.
You can make sure of this only by examining the part's drawings. Also, a more detailed visual examination of the bolt at the model will define essential geometry differences: the bolt diameter is thinner when threading through parts that were not selected. Configure the hole tolerance value to 50mm to check on the above:
Thus you can see that interbedded plates have no bolt holes, which is
It is possible to customize joinable parts of a bolted joint.
Thus select the bolted joint, and at the right-click menu, enable the
Enabling the “Bolt parts” tab highlights the current parts of a bolted joint where orange color defines the first part, and yellow color - the second part.
Now specify the new parts of the bolted connection and choose only the
Pressing the Space key or the mouse wheel button finalizes specifying
Note that the length of the bolts was configured concerning the joinable
Respecify the joinable parts of the bolted joint by selecting the two
Now, knowing that copying a bolt is done concerning the parts of a bolted joint, it is possible to replicate it to any other comparable parts. Select the bolt and in the right-click menu enable the “Copy Special” - “To another object” tab.
Further click on the respective objects. Refer to the below picture:
The bolt was successfully copied. Delete all the bolts, except for a single
Using the “Copy Special” tool, replicate the initial bolt
Particularly select each bolted joint and configure in the way all its
Make sure each part has a bolt hole.
The sequence for selecting joinable parts when creating a bolted joint.
When selecting joinable parts of a bolted connection, it is very important to follow a sequence. Let’s clarify when and why it shall be taken into consideration. When creating the assembly drawings of a project, all the descriptive tables are generated into drawings. Each drawing has a table containing various information, as well as concerning the bolts to be employed when mantling the assembly.
Let's investigate a case study where a column and a beam are connected
When creating the bolted joint, if you indicate the column as the first part, but the beam as the second one, then the bolted joint's main component will be reflected in the beam statement. Here we go, this being the main difference - the content of the statement. The bolt holes are created in any case, not depending on the joinable parts selection sequence.
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In case of the reversed sequence for selecting parts, the bolts statement
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Select the bolt and in the right-click menu, enable the “Bolt details” tab. You will get all the joinable parts highlighted with different color coding.
The color of the first part is orange .
The color of the second part is yellow, also, it is the main part of the bolted joint, as specifically, its assembly drawing will contain specifications for the bolt metalware. From the structural perspective of the TS, the bolted joint refers exactly to this part, but the other plates are considered auxiliary ones.
Another color of details
Set up the class of the plates to 4 for a further better visual representation. In the below picture, you can see two similar plate groups, though when activating the “Bolt parts” tool, you can see that parts got color-coded (thus, you can understand their selection sequence).
To disable the 'Bolt parts'' tool, press the “Esc”
In case it is of no requirement creating the statements or Excel reports, indicating the parts of an assembly and bolted joints, then the sequence of the selecting parts is of no importance.
The "User-defined attributes" section defines a set of variables to be specified by the user. Usually, this section is employed when specifying regional parameters. The set of variables of this tabcard is changeable depending on the localization package.
