Example 6: Control of concrete cracking: Estimate the stress at reinforcement (Serviceability Limit State) considering concrete tensile strength and using a parabolic concrete curve
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Data for Cross Section Analysis & Design application
We will modify the file created in Example 5 in order to re-estimate the reinforcement stresses, but considering the concrete tensile strength and using a Parabolic-Constant concrete curve for compression. In this way we can control the cracking effect of concrete.
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 5.
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.
Next, we select a Parabolic-Linear stress strain curve for compressive parts of concrete. Finally, in order to consider the tensile concrete strength, we select the “Linear and Drop to Zero” option in the tensile concrete data, as shown in the form below.
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 5, the results can be obtained from the Analysis -> Deformed configuration -> Show results menu item.
We notice that the stress at rebars 1 to 4 (bottom layer rebars) is now 208.39 MPa for load case “lc 1”.