1. Corrosion of still reinforcing bars is the most important durability problem for reinforced concrete structures. Carbonation of concrete results from a chemical reaction that lowers the pH value enough to to initiate corrosion. The table below shows a sample dependence of the strength in MPa (y) on the carbonation depth in mm (x) taken from a particular building.

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Kindly help me solve d) e) f) g). Answers for a) b) c) are in the picture attached I am aware as per policy you would solve only three, however only g) then would be remaining. So, I insist if you could help me solve all the four. Thank you!

### Study on Corrosion Impact on Reinforced Concrete Structures

#### Introduction
Corrosion of steel reinforcing bars is a critical issue affecting the durability of reinforced concrete structures. Carbonation of concrete, resulting from a chemical reaction that lowers the pH to corrosive levels, is a key factor in this degradation process. Below, we present a data table that examines the relationship between concrete strength (in MPa) and carbonation depth (in mm) from a specific building sample.

#### Data Table

| Carbonation Depth (x) [mm] | Strength (y) [MPa] |
|----------------------------|--------------------|
| 8.0                        | 22.8               |
| 15.0                       | 27.2               |
| 16.5                       | 23.7               |
| 20.0                       | 17.1               |
| 20.0                       | 21.5               |
| 27.5                       | 18.6               |
| 30.0                       | 16.1               |
| 30.0                       | 23.4               |
| 35.0                       | 13.4               |
| 38.0                       | 19.5               |
| 40.0                       | 12.4               |
| 45.0                       | 13.2               |
| 50.0                       | 11.4               |
| 50.0                       | 10.3               |
| 55.0                       | 14.1               |
| 55.0                       | 9.7                |
| 59.0                       | 12.0               |
| 65.0                       | 6.8                |

#### Analysis

**a) Linear Regression Model**
Fit a linear regression model to the data provided. Estimate the expected value of the concrete strength when the carbonation depth is 25.0 mm.

**b) Significance of Regression**
Examine the significance of the regression using the t-test with a significance level of \(\alpha = 0.01\). Report the corresponding P-value.

**c) Analysis of Variance (ANOVA)**
Use the ANOVA approach to evaluate the significance of the regression. Find and report the P-value. Compare the results with those from part (b).

**d) Validation of Model**
Test one additional sample with a carbonation depth of 25.0
Transcribed Image Text:### Study on Corrosion Impact on Reinforced Concrete Structures #### Introduction Corrosion of steel reinforcing bars is a critical issue affecting the durability of reinforced concrete structures. Carbonation of concrete, resulting from a chemical reaction that lowers the pH to corrosive levels, is a key factor in this degradation process. Below, we present a data table that examines the relationship between concrete strength (in MPa) and carbonation depth (in mm) from a specific building sample. #### Data Table | Carbonation Depth (x) [mm] | Strength (y) [MPa] | |----------------------------|--------------------| | 8.0 | 22.8 | | 15.0 | 27.2 | | 16.5 | 23.7 | | 20.0 | 17.1 | | 20.0 | 21.5 | | 27.5 | 18.6 | | 30.0 | 16.1 | | 30.0 | 23.4 | | 35.0 | 13.4 | | 38.0 | 19.5 | | 40.0 | 12.4 | | 45.0 | 13.2 | | 50.0 | 11.4 | | 50.0 | 10.3 | | 55.0 | 14.1 | | 55.0 | 9.7 | | 59.0 | 12.0 | | 65.0 | 6.8 | #### Analysis **a) Linear Regression Model** Fit a linear regression model to the data provided. Estimate the expected value of the concrete strength when the carbonation depth is 25.0 mm. **b) Significance of Regression** Examine the significance of the regression using the t-test with a significance level of \(\alpha = 0.01\). Report the corresponding P-value. **c) Analysis of Variance (ANOVA)** Use the ANOVA approach to evaluate the significance of the regression. Find and report the P-value. Compare the results with those from part (b). **d) Validation of Model** Test one additional sample with a carbonation depth of 25.0
### Linear Regression Analysis Summary

#### Summary Output
**Regression Statistics:**
- Multiple R: 0.874973816
- R Square: 0.76559179
- Adjusted R Square: 0.750927877
- Standard Error: 2.864026013
- Observations: 18

**ANOVA Table:**

| Source       | df | SS           | MS            | F           | Significance F   |
|--------------|----|--------------|---------------|-------------|------------------|
| Regression   | 1  | 428.6154577  | 428.6154577   | 52.25332287 | 2.01347E-06      |
| Residual     | 16 | 131.24232    | 8.202645003   |             |                  |
| Total        | 17 | 559.8577778  |               |             |                  |

**Coefficients Table:**

| Coefficients | Standard Error | t Stat       | P-value       | Lower 95%        | Upper 95%        | Lower 95.0%      | Upper 95.0%      |
|--------------|----------------|--------------|---------------|------------------|------------------|------------------|------------------|
| Intercept    | 27.18293605    | 1.653148135  | 16.46105716   | 1.88128E-11      | 23.68223439      | 30.68363772      | 23.68223439      | 30.68363772      |
| x            | -0.297561228   | 0.041164172  | -7.228645991  | 2.01347E-06      | -0.384825374     | -0.210297081     | -0.384825374     | -0.210297081     |

#### Analysis:

**(a)** The fitted linear regression model is: \(\hat{y} = 27.18 - 0.2976x\)

For a carbonation depth of 25.0 mm, substitute \(x = 25\) in the above equation:
\[ \hat{y} = 27.18 - 0.2976 \times (25) = 19.74 \text{ MPa}
Transcribed Image Text:### Linear Regression Analysis Summary #### Summary Output **Regression Statistics:** - Multiple R: 0.874973816 - R Square: 0.76559179 - Adjusted R Square: 0.750927877 - Standard Error: 2.864026013 - Observations: 18 **ANOVA Table:** | Source | df | SS | MS | F | Significance F | |--------------|----|--------------|---------------|-------------|------------------| | Regression | 1 | 428.6154577 | 428.6154577 | 52.25332287 | 2.01347E-06 | | Residual | 16 | 131.24232 | 8.202645003 | | | | Total | 17 | 559.8577778 | | | | **Coefficients Table:** | Coefficients | Standard Error | t Stat | P-value | Lower 95% | Upper 95% | Lower 95.0% | Upper 95.0% | |--------------|----------------|--------------|---------------|------------------|------------------|------------------|------------------| | Intercept | 27.18293605 | 1.653148135 | 16.46105716 | 1.88128E-11 | 23.68223439 | 30.68363772 | 23.68223439 | 30.68363772 | | x | -0.297561228 | 0.041164172 | -7.228645991 | 2.01347E-06 | -0.384825374 | -0.210297081 | -0.384825374 | -0.210297081 | #### Analysis: **(a)** The fitted linear regression model is: \(\hat{y} = 27.18 - 0.2976x\) For a carbonation depth of 25.0 mm, substitute \(x = 25\) in the above equation: \[ \hat{y} = 27.18 - 0.2976 \times (25) = 19.74 \text{ MPa}
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