Example 7: Control of concrete cracking by reducing the maximum reinforcement stress
Data for Cross Section Analysis & Design application
In this example, we will introduce the application of reinforcement stress limits in order to prevent the cracking of concrete. This option is available in the “Analysis Parameters” form. So, by applying the corresponding Analysis Parameters set to each analysis, the corresponding limits will be considered automatically.
In this example we will apply a tensile stress limit of 180 MPa.
As defined in Example 5.
Solution with Cross Section Analysis & Design
Opening a file from disk
First of all we click on the File menu and select Open in order to open the file we created in Example 6.
Unlock the model
Afterwards, if the model is locked, we click on Edit -> Unlock model, in order to modify the geometry of the cross section.
In the popup window, we choose Yes to unlock the model.
Review of Analysis Parameters
We need to modify the previously created Analysis Parameters set “SLS” by clicking Analysis -> Analysis Parameters and selecting “SLS” from the list at the top left corner.
At the bottom right corner of the form, we activate the option “Tensile stress limit” and enter the value 180 MPa.
Definition of load cases
The load cases do not need to be changed.
Carry out the analysis
We just click Analysis -> Deformed configuration -> Analyze, to perform the analysis.
Similarly to Example 6, the results can be obtained from the Analysis -> Deformed configuration -> Show results menu item.
The maximum tensile stress at reinforcement was 208.39 MPa in Example 5, where no reinforcement limit was applied. For the same loads (lc 1), we can now see that the cross section is now inadequate.
Cross section is adequate for the remaining load cases, where apparently the developed reinforcement stresses are smaller than the limit of 180 MPa.
Note: These limits are respected for other analysis types as well (such as Interaction diagram, Reinforcement design etc.) provided that such stress limits have been applied to the corresponding Analysis Parameters sets.