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Design a tendon layout to optimize the placement of tendons within the beam to counteract the applied beam loads.
Type:
Tutorial
Length:
5 min.
Transcript
00:03
In Structural Bridge Design, once you design a prestressed or post-tensioned beam and define the beam loads,
00:09
you can design a tendon layout.
00:12
This determines the placement, profile, and quantity of tendons, which reinforce the beam internally to counteract the applied loads.
00:22
In this scenario, a composite, pretensioned, precast beam
00:27
and a 21-meter-long, 2-meter-wide concrete slab are designed with dead loads, construction loads, live loads,
00:35
and a differential temperature profile already applied.
00:40
The next step is to optimize the tendon layout to counteract applied loads, reduce tensile stresses, and control deflections and cracking.
00:49
Keep in mind that the tendon layout requires appropriate debonding,
00:53
so that SLS and ULS criteria for bending moments and stresses are met during transfer, beam erection, and during normal use.
01:03
The tendon optimization algorithm can help you determine the best layout.
01:08
With your design open and Design Beam activated in the Navigation Pane, on the toolbar, click Analyse.
01:16
In the Pre-tensioned Beam Analysis form, click Tendon Optimisation.
01:22
In the Tendon Optimisation form, enable the Applied Load.
01:27
Then, select Debond.
01:30
Set the Locations Limit to 4 and deselect Straight.
01:36
Then, select Design Optimised Layout.
01:40
The algorithm begins running, and a warning displays to alert you that the strains exceed the limit.
01:47
Click OK.
01:50
The algorithm continues, considering possible tendon layouts.
01:55
In this example, when it is complete, an Unsatisfactory Error message appears.
02:01
A summary of the findings is included in the form, indicating that the program cannot find a solution with the current configurations.
02:09
Click OK in the Error dialog, as well as in the Tendon Optimisation form,
02:15
in the Warning dialog, and in the Pre-tensioned Beam Analysis form.
02:21
To resolve the warning and find a solution, you will need to increase the strength of the pre-stressed concrete material
02:27
and adjust the strain limit of the cast-in-place concrete.
02:31
With Materials activated in the Navigation Pane, select the MP1 material.
02:38
In the Define Property Details form, change the Ultimate Compressive Strain to .002.
02:44
Click OK.
02:47
Next, select MP2.
02:51
In the Define Property Details form, change f, ck to 50, and then press Enter.
02:59
The remaining calculations update.
03:01
Click OK.
03:04
In the Navigation Pane, activate Design Beam, and then click Analyse.
03:11
In the Warning, click OK.
03:15
Once again, in the Pre-tensioned Beam Analysis form, click Tendon Optimisation,
03:20
and in the Tendon Optimisation form, adjust the Debonding Limits per Jump to 30.
03:26
Click Design Optimised Layout.
03:29
This time, the tendon optimization algorithm runs without the previous error.
03:35
However, a new error message displays.
03:39
Click OK to close this message and then OK again to close the Tendon Optimisation form.
03:46
A warning informs you that the compressive stresses at transfer are shown in red, indicating a failure;
03:52
because, in some locations, the stresses exceed the basic limiting compressive stress.
03:57
However, the code allows for an increase in this limit, if justified.
04:03
In addition, you can consider possible enhancements to address this issue, such as curing the concrete at a higher temperature.
04:11
Click OK to close the dialog.
04:14
To adjust the temperature, in the Pre-tensioned Beam Analysis form,
04:18
adjust the Set Parameters for drop-down to Time dependent effect calculations.
04:23
Then, in the corresponding form, set the Ambient temperature to 28.
04:29
Click OK.
04:32
If you receive an error message, dismiss it.
04:36
Using the tendon optimization algorithm, you can design an optimized tendon layout to counteract beam loads
04:42
by iteratively refining your tendon layout and material properties.
Video transcript
00:03
In Structural Bridge Design, once you design a prestressed or post-tensioned beam and define the beam loads,
00:09
you can design a tendon layout.
00:12
This determines the placement, profile, and quantity of tendons, which reinforce the beam internally to counteract the applied loads.
00:22
In this scenario, a composite, pretensioned, precast beam
00:27
and a 21-meter-long, 2-meter-wide concrete slab are designed with dead loads, construction loads, live loads,
00:35
and a differential temperature profile already applied.
00:40
The next step is to optimize the tendon layout to counteract applied loads, reduce tensile stresses, and control deflections and cracking.
00:49
Keep in mind that the tendon layout requires appropriate debonding,
00:53
so that SLS and ULS criteria for bending moments and stresses are met during transfer, beam erection, and during normal use.
01:03
The tendon optimization algorithm can help you determine the best layout.
01:08
With your design open and Design Beam activated in the Navigation Pane, on the toolbar, click Analyse.
01:16
In the Pre-tensioned Beam Analysis form, click Tendon Optimisation.
01:22
In the Tendon Optimisation form, enable the Applied Load.
01:27
Then, select Debond.
01:30
Set the Locations Limit to 4 and deselect Straight.
01:36
Then, select Design Optimised Layout.
01:40
The algorithm begins running, and a warning displays to alert you that the strains exceed the limit.
01:47
Click OK.
01:50
The algorithm continues, considering possible tendon layouts.
01:55
In this example, when it is complete, an Unsatisfactory Error message appears.
02:01
A summary of the findings is included in the form, indicating that the program cannot find a solution with the current configurations.
02:09
Click OK in the Error dialog, as well as in the Tendon Optimisation form,
02:15
in the Warning dialog, and in the Pre-tensioned Beam Analysis form.
02:21
To resolve the warning and find a solution, you will need to increase the strength of the pre-stressed concrete material
02:27
and adjust the strain limit of the cast-in-place concrete.
02:31
With Materials activated in the Navigation Pane, select the MP1 material.
02:38
In the Define Property Details form, change the Ultimate Compressive Strain to .002.
02:44
Click OK.
02:47
Next, select MP2.
02:51
In the Define Property Details form, change f, ck to 50, and then press Enter.
02:59
The remaining calculations update.
03:01
Click OK.
03:04
In the Navigation Pane, activate Design Beam, and then click Analyse.
03:11
In the Warning, click OK.
03:15
Once again, in the Pre-tensioned Beam Analysis form, click Tendon Optimisation,
03:20
and in the Tendon Optimisation form, adjust the Debonding Limits per Jump to 30.
03:26
Click Design Optimised Layout.
03:29
This time, the tendon optimization algorithm runs without the previous error.
03:35
However, a new error message displays.
03:39
Click OK to close this message and then OK again to close the Tendon Optimisation form.
03:46
A warning informs you that the compressive stresses at transfer are shown in red, indicating a failure;
03:52
because, in some locations, the stresses exceed the basic limiting compressive stress.
03:57
However, the code allows for an increase in this limit, if justified.
04:03
In addition, you can consider possible enhancements to address this issue, such as curing the concrete at a higher temperature.
04:11
Click OK to close the dialog.
04:14
To adjust the temperature, in the Pre-tensioned Beam Analysis form,
04:18
adjust the Set Parameters for drop-down to Time dependent effect calculations.
04:23
Then, in the corresponding form, set the Ambient temperature to 28.
04:29
Click OK.
04:32
If you receive an error message, dismiss it.
04:36
Using the tendon optimization algorithm, you can design an optimized tendon layout to counteract beam loads
04:42
by iteratively refining your tendon layout and material properties.
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