// CODE SNIPPET

# 8.4.14 Elevator Seismic Design Force

JUMP TO FULL CODE CHAPTER

The seismic force shall be computed per requirements of IBC or NBCC-2005 or later editions, in accordance with the applicable building code.

*(a)* For IBC

*F _{p}* = component seismic force level (horizontal, strength design level) =

*F _{p}* is not required to be taken as greater than

*F _{p}* = 1.6

*S*

_{DS}l_{p}W_{p}and *F _{p}* shall not be taken as less than

*F _{p}* = 0.3

*S*

_{DS}l_{p}W_{p}where

a_{p} |
= | component amplification factor = 1.00 |

F_{p} |
= | component seismic force level (horizontal, strength design level) |

h |
= | average roof height of the structure with respect to the defined building base, provided by the building structural engineer |

l_{p} |
= | component importance factor = 1.00 or 1.50 |

R_{p} |
= | component response modification factor = 2.5 |

S_{DS} |
= | 5% damped design spectral response acceleration for short periods (i.e., 0.2 s) |

W_{p} |
= | component operating weight as defined in 8.4.15 |

z |
= | height in the structure of the point of attachment of the component with respect to the defined building base provided by the building structural engineer. For items at or below the base, z shall be taken as 0. The value of z/h need not exceed 1.0. (See Section 1.3 for the definition of "base, building" and see Guide for Elevator Seismic Design, Part 1.) |

NOTES:

- For isolated components, refer to ASCE 7-10, Table 13.6-1.
*F*shall be multiplied by a factor of 0.7 for stress calculations to convert from strength design (IBC) to allowable stress design (ASME A17.1). This factor is already included in the load combinations in 8.4.14.1.2._{p}

*(b)* For NBCC-2005 or later editions

F_{p} |
= | component seismic force level (horizontal, strength design level) = 0.3F(0.2) _{a} S_{a}I_{E} S_{p} W_{p} |

where

F_{a} |
= | acceleration-based site coefficient, defined in NBCC-2010, Table 4.1.8.4.B, based on S(0.2) and site class, A through F_{a} |

F_{p} |
= | component seismic force level (horizontal, strength design level) |

I_{E} |
= | importance factor for the building, defined in NBCC-2010, Article 4.1.8.5 |

S_{a}(0.2) |
= | 5% damped spectral response acceleration value, expressed as a ratio to gravitational acceleration, for a period of 0.2 s, defined in NBCC-2010, sentence 4.1.8.4(1) |

S_{p} |
= | C/_{p} A_{r} A_{x}R (where _{p}S may range between 0.7 and 4.0) with_{p} |

A_{r} |
= | component force amplification factor from NBCC-2010, Table 4.1.8.18 |

A_{x} |
= | height factor (1 + 2 h/_{x}h) with_{n} |

h_{x} |
= | height in the structure of the point of attachment of the component with respect to the defined building base provided by the building structural engineer. For items at or below the base, z shall be taken as 0. (See Section 1.3 for the definition of "base, building" and see Guide for Elevator Seismic Design, Part 1.) |

h_{n} |
= | average roof height of the structure with respect to the defined building base, provided by the building structural engineer. The value of h/_{x}h need not exceed 1.0._{n} |

C_{p} |
= | component factor as listed in NBCC-2010, Table 4.1.8.18 |

R_{p} |
= | component response modification factor from NBCC-2010, Table 4.1.8.18 |

W_{p} |
= | component operating weight as defined by 8.4.15 |

NOTES:

- For isolated components, refer to NBCC-2010, Table 4.1.8.18.
*F*shall be multiplied by a factor of 0.7 for stress calculations to convert from strength design (NBCC-2010) to allowable stress design (ASME A17.1). This factor is already included in the load combinations in 8.4.14.1.2._{p}- Elevator equipment subject only to inertial accelerations of their own mass are considered rigid components when referencing NBCC-2010, Table 4.1.8.18 for variables
*C*,_{p}*A*, and_{r}*R*. Elevator equipment subjected to accelerations and decelerations and subject to external forces independent of the mass of the component itself are considered machinery._{p}

The seismic design force,

*F*, shall be applied at the component's center of gravity. In addition, the component shall be designed for concurrent vertical seismic force_{p}*F*equal to_{v}*(a)* ±0.2 *S _{DS}W_{p}* (for IBC)

*(b)* ±0.2 [^{2}/_{3}*F _{a}S_{a}*(0.2)]

*W*(for NBCC)

_{p}NOTES:

- Guide rail mounted machinery would be an example of vertical loads imposed on the guide rail in addition to the horizontal inertial loads (see 8.4.8.2.6 and 8.4.14.1.1).
*F*shall be multiplied by a factor of 0.7 for stress calculations to convert from strength design (NBCC-2010) to allowable stress design (ASME A17.1). This factor is already included in the load combinations in 8.4.14.1.2._{v}

Components and portions thereof shall resist the most critical effects resulting from the more stringent of the following combinations of loads:

For IBC/NBCC

*(a)* (*D* + 0.7*E*)

*(b)* (0.6*D* + 0.7*E*)

where

D | = | dead load |

E | = | earthquake load = F + _{p}F_{v} |

Increases in allowable stresses shall not be used.

### Related Code Sections

8.4.14 General Requirements, Elevator Seismic Design Force

(a) For IBC/ASCE 7 F p = Component

*Seismic**Force*Level (horizontal, Strength*Design*Level) = F p is not required to be taken ...
Safety Code for Elevators and Escalators 2013 of Colorado > 8 General Requirements > 8.4 Elevator Seismic Requirements > 8.4.14 Elevator Seismic Design Force

8.4.14 General Requirements, Elevator Seismic Design Force

(a) For IBC
F p = component

*seismic**force*level (horizontal, strength*design*level) = F p is not required to be taken as greater than F p ...
Safety Code for Elevators and Escalators 2019 of Colorado > 8 General Requirements > 8.4 Elevator Seismic Requirements > 8.4.14 Elevator Seismic Design Force

8.4.14.1.2 General Requirements, Load Combinations Using Allowable Stress Design

Components and portions thereof shall resist the most critical effects resulting from the more stringent of the following combinations of loads: For ...

Safety Code for Elevators and Escalators 2019 of Colorado > 8 General Requirements > 8.4 Elevator Seismic Requirements > 8.4.14 Elevator Seismic Design Force > 8.4.14.1 Component Seismic Force Level (Strength Design) > 8.4.14.1.2 Load Combinations Using Allowable Stress Design

8.4.14.1.3 General Requirements, Stress Increases

Increases in allowable stresses shall not be used ...

Safety Code for Elevators and Escalators 2013 of Colorado > 8 General Requirements > 8.4 Elevator Seismic Requirements > 8.4.14 Elevator Seismic Design Force > 8.4.14.1 Component Seismic Force Level (Strength Design) > 8.4.14.1.3 Stress Increases

8.4.14.1.3 General Requirements, Stress Increases

Increases in allowable stresses shall not be used ...

Safety Code for Elevators and Escalators 2019 of Colorado > 8 General Requirements > 8.4 Elevator Seismic Requirements > 8.4.14 Elevator Seismic Design Force > 8.4.14.1 Component Seismic Force Level (Strength Design) > 8.4.14.1.3 Stress Increases