# Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment

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## Abstract

**:**

## 1. Introduction

## 2. Analytical Model for Cabinet Assembly

#### 2.1. Development Steps

#### 2.2. Modal Testing

#### 2.3. Numerical Modeling

#### 2.4. Validation of FE Models

## 3. Mathematical Model for Interconnected Cabinets

## 4. Uncertainties in In-Cabinet Response Generation

#### 4.1. Grouping Effects of the Cabinet

#### 4.2. Effect of the In-Cabinet Component Load

#### 4.3. Influence on ICRS due to Input Protocol

## 5. Result and Discussion

#### 5.1. In-Cabinet Components and Grouping Effect of the Cabinets

#### 5.2. Seismic Response of the Inter-Connected Cabinet Assemblies

#### ICRS under the Low and High Frequency Pluses

## 6. Effect on the Seismic Qualification

## 7. Conclusions

- Grouping effect of the cabinets considering the internal equipment reduces the seismic response on one hand, but it can considerably amplify the response due to inherent ground motion parameters.
- Grouping effect under the low-frequency input motion has a constant de-amplification almost (50%) in the in-cabinet response that corresponds to the higher stiffness provided by the number of cabinets as shown in Figure 18. Meanwhile, under the high frequency of ground motion, the response is dramatically amplified. High frequency of ground motion usually above 10 Hz can cause the interconnected cabinets to resonate as the natural frequency of this equipment lies in this range.
- High frequency of the multi-cabinets manifests the higher stiffness, however the energy of the strong motion can amplify the response of the cabinets as compared to a single cabinet.
- Using the standard design spectra (RG 1.60) the comparative response of the cabinets represents no potential difference on the ICRS while it is significantly amplified by the seismic inputs having high frequency pulses.
- Cabinets connected in series may have high integral stiffness, but due to their sensitivity to the input motion parameters, they can be more vulnerable than a stand-alone cabinet. This analysis is based on a cabinet prototype that has less stiffness than the available NPP cabinets, in this regards the grouping effect for the cabinets having higher stiffness can be more effective.
- Future extension in this domain can be considered by investigating the nonlinear dynamic interaction of the cabinets having different dynamic characteristics as in this study the cabinet was considered to have the same dynamic properties.

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 3.**Cabinets prototype under different loading condition: (

**a**) Empty cabinet; (

**b**) Loaded at the top; (

**c**) Fully loaded.

**Figure 6.**Natural frequencies from Experimental and Numerical modal analysis: (

**a**) Empty Cabinet; (

**b**) Loaded Cabinet at the top; (

**c**) Fully loaded Cabinet.

**Figure 9.**Effect on the natural frequencies of cabinets considering k_3; (

**a**) Effect of mass ratio; (

**b**) Effect of stiffness ratio.

**Figure 10.**Numerical models for the grouping effect of the cabinets; (

**a**) Single Cabinet; (

**b**) Two cabinet assembly; (

**c**) Three cabinet assembly; (

**d**) Four cabinet assembly; (

**e**) Five cabinet assembly (

**f**) Six cabinet assembly.

**Figure 11.**Seismic inputs for the ICRS generation: (

**a**) Low frequency earthquakes (below 10 Hz); (

**b**) High frequency earthquakes (above 10 Hz); (

**c**) Scaled ground motions with artificial ground motions compatible with RG 1.60.

**Figure 13.**Cabinet response under the Artificial ground motion compatible with RG 1.60; (

**a**) Acceleration response; (

**b**) Maximum In-Cabinet response.

**Figure 14.**Seismic response of cabinets assemblies under Victoria_ Mexico: (

**a**) Acceleration response for one and two cabinets; (

**b**) Multi-cabinets acceleration response; (

**c**) Maximum ICRS for one and two cabinets; (

**d**) Maximum ICRS for multi-cabinets.

**Figure 15.**Seismic response of cabinets under the Goungju Earthquake: (

**a**) Acceleration response; (

**b**) Maximum In-cabinet response spectra.

**Figure 16.**Seismic response of cabinets under Mexico Nahani Canada earthquake: (

**a**) Acceleration response for one and two cabinets; (

**b**) Acceleration response for multi-cabinets; (

**c**) Maximum ICRS for one and two cabinets; (

**d**) ICRS for multi-cabinets.

**Figure 17.**Acceleration response under El Mayor-Cucapah_ Mexico Earthquake: (

**a**) Acceleration response for one and two cabinets (

**b**) response from multi-cabinet (

**c**) Maximum ICRS for one and two cabinets (

**d**) Maximum ICRS for multi-cabinets.

Size | 2100 (H) × 800 (W) × 800 (D) mm |

Weight | 290 kg |

Internal Dead Load (Assumed) | 200 kg per cabinet |

Elastic Modulus, Density$\left(\mathit{\rho}\right)$, and Poisson’s Ratio$\left(\mathit{\nu}\right)$ | 200 GPa, 7850 kg/m^{3}, and 0.3 |

Bolt Size | M14 × 80 |

No | Earthquake Name | Year | Magnitude | ${\mathit{R}}_{\mathit{R}\mathit{U}\mathit{P}}\left(\mathbf{km}\right)$ | ${\mathit{V}}_{\mathit{s},30}\text{}(\mathbf{m}/\mathbf{sec})$ |
---|---|---|---|---|---|

1 | Victoria_Mexico | 1980 | 6.33 | 14.37 | 471.53 |

2 | Nahanni_Canada | 1985 | 6.76 | 9.6 | 605.04 |

3 | Cape Mendocino | 1992 | 7.01 | 6.96 | 567.78 |

4 | Landers | 1992 | 7.28 | 69.21 | 382.93 |

5 | Northridge-01 | 1994 | 6.69 | 68.93 | 501.75 |

6 | Northridge-01 | 1994 | 6.69 | 47.98 | 544.68 |

7 | Hector Mine | 1999 | 7.13 | 43.05 | 382.93 |

8 | El Mayor-Cucapah_Mexico | 2010 | 7.2 | 45.47 | 523.99 |

9 | Goungju_South Korea | 2016 | 5.7 | 14 | 550.60 |

Number of Cabinets | 1 | 2 | 3 | 4 | 5 | 6 | |
---|---|---|---|---|---|---|---|

Frequency (Hz) | Empty Cabinet | 9.87 | 13.60 | 15.46 | 15.87 | 15.90 | 16.02 |

Loaded Cabinet | 9.69 | 11.95 | 12.55 | 12.83 | 12.96 | 12.98 |

Stiffness Ratio | Mass Ratio | Modal Characteristic | ||||
---|---|---|---|---|---|---|

No. of Cabinets | Modal Stiffness (kN/m) | Difference | Modal Mass (kg) (Active/Total) | Difference | Modal Frequency (Hz) | Modal Mass Participation % |

1 | 4403 | ----- | 365/480 | ------ | (9.8) | 77.11 |

2 | 7262 | 40% | 672/960 | 50% | (11.95) | 77.18 |

3 | 7851 | 8% | 1008/1440 | 34% | (12.55) | 77.80 |

4 | 8294 | 5.3% | 1344/1920 | 25% | (12.87) | 77.84 |

5 | 8561 | 4% | 1680/2400 | 18% | (12.96) | 77.88 |

6 | 8739 | 2% | 2016/2880 | 16.65% | (12.98) | 77.88 |

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## Share and Cite

**MDPI and ACS Style**

Salman, K.; Gook Cho, S. Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment. *CivilEng* **2020**, *1*, 198-215.
https://doi.org/10.3390/civileng1030012

**AMA Style**

Salman K, Gook Cho S. Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment. *CivilEng*. 2020; 1(3):198-215.
https://doi.org/10.3390/civileng1030012

**Chicago/Turabian Style**

Salman, Kashif, and Sung Gook Cho. 2020. "Effect of Frequency Content of Earthquake on the Seismic Response of Interconnected Electrical Equipment" *CivilEng* 1, no. 3: 198-215.
https://doi.org/10.3390/civileng1030012