# Impact of the Reinforcement Detailing on Seismic Performance of Isolated Non-structural Walls

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## Abstract

**:**

## 1. Introduction

## 2. Experimental Study

#### 2.1. Test Specimen

_{l}, was similar for the beams of all specimens; but differed for the walls.

#### 2.2. Testing Program of the Specimen

## 3. Experimental Results

#### 3.1. Damage Outline

#### 3.2. Load–Deflection Relation

#### 3.3. Drift Capacity

- There is a non-anchored detailing of longitudinal reinforcement;
- The amount of longitudinal reinforcement is equal or greater than transverse reinforcement;
- The confinements are placed at the critical zone of the wall.

#### 3.4. Strain–Drift Relationship of Trasnverse Reinforcements

_{1}, as shown in Figure 4a, encounters a bigger amount of strain in the negative loading due to the accumulation of cracks near the lower stab rather than spreading along the length of the wall, as seen in Figure 10a. Conversely, specimen 3NA experienced a lower strain for the negative loading, because the cracks spread along the length of the hanging wall, as shown in Figure 10b. As seen in Figure 10d, boundary-confined bars were more operational for carrying tensile and compressive loads rather than sectional confinements, which address the condition of the displacement design approach. Similarly, the performance of sectional confinement stirrup of specimen 12NA and boundary confinement of specimen 12HN were almost alike, as shown in Figure 10c,d. This is because the anchored bars of specimen 12NA could transfer more stress to the stirrup during the loading, resulting in the stirrup experiencing similar strain as the 12HN confined stirrup.

## 4. Evaluation of the Experimental Results

#### 4.1. Evaluation of the Strength

#### 4.2. Evaluation of the Confinement and Reinforcement Detailing Impact

- To calculate internal forces, the stress incurred in every longitudinal reinforcement was calculated based on the strain gauge record pasted on the longitudinal reinforcement, as shown in Figure 4. The strain records from gauges V1, V5, L1, and L2 were used for stress analysis of specimens 3NN and 3NA, and the strain records from V1, V6, V9, L1, and L2 were used for the other specimens.
- The concrete compressive force N
_{cc}was extrapolated using the equilibrium Equation (1).$$\begin{array}{c}{N}_{CC}={\displaystyle \sum}{N}_{T}-{\displaystyle \sum}{N}_{CS}\end{array}$$_{T}(N_{1}, N_{2}) and N_{CS}are tensile and compressive forces, respectively, as shown in Figure 13, determined according to the strain gauge records installed on the longitudinal bars. - Neutral axis C
_{b}was calculated using the curvature ϕ of the specimen. Curvature was calculated according to the strain gauge records L1 and L2 (ε_{1}, ε_{2}) installed on the D13 and D16 reinforcement bars (See Figure 4). Using neutral axis and curvature, the compressive strain at the extreme compression fiber was calculated. - Effective concrete compressive stress f
_{ce}and compressive strain ε_{cu}was found using Equations (2) and (3):$$\begin{array}{c}{f}_{ce}=\frac{{N}_{cc}}{0.85\times \beta {C}_{b}\times d}\end{array}$$$$\begin{array}{c}{\epsilon}_{cu}=\varphi \times {C}_{b}\end{array}$$

_{cc}is the compressive strength of the confined concrete, which is directly related to the effective confining stress f’

_{l}, as given in Equations (5) and (6) for a rectangular section in the x and y directions.

_{x}and ρ

_{y}are the effective section area ratios of the transverse reinforcement to the core concrete, K

_{e}is the confinement effectiveness coefficient with a typical value of 0.6 for the rectangular wall sections. Confined compressive stress is calculated using K from a biaxial chart.

_{c}and E

_{sec}are the tangent and secant modulus of the concrete.

#### 4.3. Evaluation of the Stress Transition Mechanism

## 5. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**(

**a**) Proposed detailing of a frame with a hanging wall with and without a seismic slit; and (

**b**) their expected performance.

**Figure 4.**Specimen configuration: (

**a**) anchored case with minimum reinforcement; (

**b**) anchored case with only sectional confinement; and (

**c**) non-anchored case with confinement.

**Figure 6.**Damage outline at the drift limit +0.02 rad: (

**a**) 3NN; (

**b**) 3NA; (

**c**) 6NA; (

**d**) 12NA; (

**e**) 12HN; (

**f**) 18NNT.

**Figure 8.**Comparison of load–deflection curve: (

**a**) 3NN; (

**b**) 3NA; (

**c**) 6NA (

**d**) 12NA; (

**e**) 12HN; (

**f**) 18NNT.

**Figure 10.**Strain–drift relation of the critical transverse reinforcement: (

**a**) 3NN; (

**b**) 3NA; (

**c**) 12NA; (

**d**) 12HN.

**Figure 15.**Mechanism of confinement and detailing impacts on the concrete core: (

**a**) anchored detailing and (

**b**) non-anchored detailing.

ID | Cross Section | Transverse Reinforcement | Longitudinal Reinforcement | Boundary Confinement | Anchoring of Main Bar | Notice | |||
---|---|---|---|---|---|---|---|---|---|

Wall | Beam | Wall | Beam | Ratio | Depth (mm) | ||||

3NN | 100 × 150 | D4@100 (ρ _{t} = 0.28%) | D6@50 (ρ _{t} = 1.3%) | 4-D4 (ρ _{l} = 0.37%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | No | |||

3NA | D4@100 (ρ _{t} = 0.28%) | D6@50 (ρ _{t} = 1.3%) | 4-D4 (ρ _{l} = 0.37%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | - | - | Yes | Min. ^{1} | |

6NA | D6@100 (ρ _{t} = 0.63%) | D6@50 (ρ _{t} = 1.3%) | 6-D6 (ρ _{l} = 1.26%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | Yes | Med. ^{2} | |||

12NA | D6@50 (ρ _{t} = 1.27%) | D6@50 (ρ _{t} = 1.3%) | 6-D6 (ρ _{l} = 1.26%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | Yes | Max. ^{3} | |||

12HN | D6@50 (ρ _{t} = 1.27%) | D6@50 (ρ _{t} = 1.3%) | 6-D6 (ρ _{l} = 1.26%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | 1.27% | 450 | No | Max. ^{3} | |

18NNT | 75 × 150 | D6@50 (ρ _{l} = 1.69%) | D6@50 (ρ _{t} = 1.3%) | 6-D6 (ρ _{l} = 1.69%) | 4-D16 4-D13 (ρ _{l} = 6.51%) | - | - | No | Slend. ^{4} |

^{1}Minimum reinforcement used in this test.

^{2}Medium reinforcement used in this test.

^{3}Maximum reinforcement used in this test.

^{4}Slenderness impact.

Compressive Strength f’_{c} (MPa) | Strain at Peak (%) | Young’s Modulus (MPa) | Tensile Strength (Mpa) |
---|---|---|---|

36.3 | 0.212 | 17,374.6 | 2.7 |

Reinforcements | Young’s Modulus (GPa) | Yield Stress (MPa) | Ultimate Strength (MPa) |
---|---|---|---|

D4 | 178.8 | 356.7 | 503.5 |

D6 | 185.6 | 338.3 | 501.7 |

D13 | 201.3 | 380.6 | 506.2 |

D16 | 203.4 | 383.8 | 568.9 |

Specimen | Ultimate Strength Capacity V_{exp} ^{1} (kN) | Analytical Prediction V_{ana} ^{2} (kN) | V_{exp}/V_{ana}(%) |
---|---|---|---|

3NN | 85.2 | 101.8 | 84 |

3NA | 92.8 | 104.9 | 88 |

6NA | 106.2 | 110.5 | 96 |

12NA | 115.8 | 110.5 | 105 |

12HN | 116.8 | 101.8 | 115 |

18NNT | 86.2 | 80.4 | 107 |

^{1}Experimental ultimate lateral load capacity.

^{2}Analytical ultimate lateral load capacity.

Specimen | Drift Capacity (%) | Neutral Axis Depth (mm) | Effective Compressive Strength (MPa) | Ultimate Compressive Strain |
---|---|---|---|---|

3NN | 0.040 | 144 | 40.8 | 0.0031 |

3NA | 0.038 | 150 | 40.5 | 0.0037 |

6NA | 0.040 | 161 | 39.8 | 0.0064 |

12NA | 0.037 | 134 | 48.3 | 0.0033 |

12HN | 0.099 | 148 | 50.3 | 0.0069 |

18NNT | 0.040 | 161 | 51.7 | 0.0055 |

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**MDPI and ACS Style**

Safi, W.A.; Hibino, Y.; Kusunoki, K.; Sanada, Y.; Mukai, T.
Impact of the Reinforcement Detailing on Seismic Performance of Isolated Non-structural Walls. *Buildings* **2020**, *10*, 89.
https://doi.org/10.3390/buildings10050089

**AMA Style**

Safi WA, Hibino Y, Kusunoki K, Sanada Y, Mukai T.
Impact of the Reinforcement Detailing on Seismic Performance of Isolated Non-structural Walls. *Buildings*. 2020; 10(5):89.
https://doi.org/10.3390/buildings10050089

**Chicago/Turabian Style**

Safi, Walid Ahmad, Yo Hibino, Koichi Kusunoki, Yasushi Sanada, and Tomohisa Mukai.
2020. "Impact of the Reinforcement Detailing on Seismic Performance of Isolated Non-structural Walls" *Buildings* 10, no. 5: 89.
https://doi.org/10.3390/buildings10050089