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.

Load cases

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.

Unlocking the model to enable editing

In the popup window, we choose Yes to unlock the model.

Unlock model confirmation

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.

Applying a tensile stress limit for reinforcement for SLS analysis parameters set

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.

Results

Similarly to Example 6, the results can be obtained from the Analysis -> Deformed configuration -> Show results menu item.

Cross section is inadequate for load case 1, after the application of the stress limit

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.

Cross section is adequate for load case 2. Reinforcement stress does not exceed 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.