More than 40 U.S. states have replaced their legacy building code with the International Building Code (IBC). In this paper, we will explore the impact of this transition as it relates to the elevator seismic requirements under the ASME A17.1/CSA B44 Elevator Code (See Section 8.4).
 
Prior to the 2013 code, elevator component seismic force levels were determined by either seismic zone or ground motion. However, for jurisdictions under IBC, this long standing approach of needing only one value to determine elevator component seismic force level is no longer valid.

Transition of Seismic Design criteria in Model Codes

The intent of the seismic design criteria in model codes is to minimize property damage and maintain function during and after an earthquake. This seismic design criterion has evolved to the point where, under the IBC as incorporated in the 2013 version of the elevator code, the traditional “Seismic Zone” approach used in elevator design and installation is no longer applicable. The criterion used in the IBC is called “Seismic Design Category.” For the United States’ building industry,
this transition has been going on for a number of years. Table 1 (page 3) shows the building code’s evolution during this transition from Seismic Zones to Seismic Design Category.
 
The elevator code retains the seismic zone approach by allowing equivalence to or comparison with a seismic zone, given a ground motion parameter, during this transition period. This equivalence is based on the Affected Peak Velocity Acceleration Parameter (AV). However, the transition period is over, a fact which is readily apparent with the publication of the 2013 elevator code. So what does this mean for those jurisdictions who adopted the IBC Seismic Design Category? See Table 2 (page 3) for the comparison between Affected Peak Velocity Acceleration and Seismic Zone. This comparison has been in the A17.1 elevator code since 2000 and continues to be in the 2013 elevator code.
 
Where the new code has been adopted, the elevator manufacturer/installer must obtain a number of seismic parameters in order to determine the applicable force levels to be applied to the installed elevator equipment.

Seismic Design parameters in the IBC

Under the IBC, which references ASCE 7, there are a number of seismic parameters that the elevator manufacturer/installer must know in order to bid, design, specify, layout, and install the elevator equipment in a building designed under IBC. These parameters are needed before the elevator manufacturer/installer can determine if Section 8.4 of the elevator code will or will not apply to the installation. These parameters are also specified in ASCE 7, American Society of Civil Engineers – Minimum Design Loads for Buildings and Other Structures. You can see the design parameters in detail in Table 3 (page 3).

To assist elevator manufacturers/installers in acquiring the required seismic parameters in conformance with IBC and the 2013 elevator code, a Seismic Requirements Data Form is available on the NEII web site. Member companies can use this form to request the required seismic data from the building designer.

When does section 8.4 apply?

Legacy building codes allow force level calculations based on either seismic zone or ground motion Av. Where IBC has been adopted, force levels must be based on a number of seismic parameters (aka seismic design) as dictated in Section 8.4. For the elevator manufacturer/installer, the first concern is whether or not Section 8.4 applies to his/her particular project.
 
As listed in the first two sections of Table 3, Seismic Design Category and the Component Importance Factor, A17.1-2013/B44-13 requirements 8.4(a)(1) and 8.4(a)(2), respectively, are the key factors used to determine if the Elevator Seismic Requirements do or do not apply to the installation. (As a rule, A17.1/B44, Section 8.4, Elevator Seismic Requirements are considered applicable where either of the following exist

• 8.4(a)( (1) Seismic Design Category C with Component Importance Factor, Ip, of 1.5 as defined by IBC (see 1.3, building code) 
• 8.4(a)( (2) Seismic Design Category D or greater as defined by IBC (see 1.3, building code)
  

A determination that seismic design is not required occurs where either of these conditions apply:

• Buildings with Seismic Design Categories A or B,
  
• Buildings with Seismic Design Category C where the Component Importance Factor is 1.0. 
  

A17.1-2013/B44-13 Incorporating IBC - How does section 8.4 apply?

If the Section 8.4 requirements do apply, the elevator manufacturer/installer is required to determine the Elevator Seismic Design Forces FP and FV and other parameters as given in Section 8.4.14. For the United States these forces and parameters are based on IBC with reference to ASCE 7. These seismic calculations and parameters are provided below in Table 4.

A17.1-2013/B44-13 Incorporating IBC - What section 8.4 requirements are impacted?

Elevator equipment installations under IBC have parameters differ from the traditional seismic zones approach. Some of the 8.4 requirements that are impacted where there is a difference in the determination and application of normal and seismic forces between the zone approach and the IBC approach are given below in Table 5.

A17.1-2013/B44-13 Incorporating IBC - What is the impact to rail bracket spacing?

Under IBC, the permissible seismic force per pair of rails is determined from the horizontal force FP based on WP instead of directly from the Component Operating Weight WP. The guide rail bracket spacing will now decrease as a function of vertical location within the structure, i.e., the higher the bracket is located in the building, the closer the bracket spacing should be. This decrease in bracket spacing occurs due to the amplification factor [1 + 2(z/h)] that is applied to WP. (See Equation FP in Table 4.)  
 
As examples, bracket pairs installed at the building base will have an amplification factor of 1 applied to WP while bracket pairs installed at the roof level will have an amplification factor of 3 applied to WP. Intermediate bracket pairs will then fall somewhere between 1 and 3. To determine the required bracket spacing for various rail sizes, see Figures 8.4.8.2-1 through 8.4.8.2-7 in the 2013 elevator code.
 
The FP value as given in Table 4 is needed to determine the vertical bracket spacing for each bracket pair. The actual force value to be applied to Figure 8.4.2.2-1 through 8.4.8.2-7 vertical axis is 2.93 x 0.7 x FP. Further, these calculations include the amplification factor [1 + 2(z/h)] and as such will vary as a function of the vertical location of the guide-rail bracket relative to the building base. In order to perform these calculations, the person preparing the layout drawing must have the building base (b) and height (h) information.
 
This is critical data called for on the Seismic Requirement Data Form. From the base and height information, the person preparing the layout will determine the location of the bracket (z) relative to the base (b). It is at this point that the amplification factor can be known and the FP value for each rail pair determined. Given FP, the person preparing the layout can now determine rail bracket spacing. (See the appropriate Figure 8.4.8.2-1 through 8.4.8.2-7 in the 2013 elevator code).
 
Given parameters FP and FV, the F x-x and F y-y normal forces are also calculated and provided on the layout drawings. Without completing the above steps, one cannot prepare layout drawings that comply with IBC and the 2013 elevator code. Without this calculation, it is also not possible to determine the precise number of car and counterweight bracket pairs for the installation.

A17.1-2013/B44-13 Incorporating IBC - Are there additional impacts to layout drawings?

Eliminating counterweight derailment detection

Under IBC, the seismic zone approach no longer applies when determining whether or not a displacement switch (counterweight derailment) and the associated operation required by 8.4.10.1.1 may be eliminated. Instead, this determination is based on the calculation of seismic force FP. If all the conditions given in Table 7 are met, then the manufacturer installer may opt out of providing counterweight derailment detection.

Alternatively, the option to not provide counterweight derailment detection can be made without having to calculate FP. This can be done using only the data given on the Seismic Requirement Data Form. The seismic parameters required to make this determination are Seismic Design Category (SDC) Component Importance Factor IP and Spectral Response Acceleration SDS. If all the conditions given in Table 8 are met, then the manufacturer installer may opt out of providing counterweight derailment detection.
 
It is also important to note that under IBC, there are a number of places in Section 8.4 where the determination of the seismic design forces first requires calculating Horizontal Strength Level FP and Concurrent Vertical Seismic Force FV using the equations given in Table 9. Having a means to determine zone equivalence may be useful in earlier bidding and evaluating requirements.
 
Table 10 gives a rough zone equivalence within the parameters of Seismic Design Category (SDC), Component Importance Factor IP and Spectral Response Acceleration for Short Period SDS.

Conclusion

As more and more buildings are being constructed under IBC, it is critical for elevator manufacturers/ installers to align themselves with the new IBC seismic requirements as applied in the A17.1-2013/B4413 elevator code.  

August 29, 2019

In light of a recent tragic and highly publicized accident in the U.S., the National Elevator Industry, Inc. (NEII) feels it is important to reaffirm the many measures our industry undertakes to provide a consistently high standard of safety.

Safety is the Elevator and Escalator Industry’s First Priority

NEII and its member companies are committed to the promotion of safe building transportation and continue to aggressively work toward improving and ensuring adoption of stringent safety codes, developing safer products and helping to educate the public on safe riding practices. While we cannot prevent every accident, we strongly believe that accidents such as these should never happen, and that it is our responsibility – from manufacturers, owners, managers and inspectors to the riding public – to uphold this overall commitment to safety.

Elevator Safety Codes Ensure Safe Equipment, Regular Maintenance and Inspections

The industry does have stringent codes in place to help ensure the safety of its products, and to make certain that machinery is maintained and inspected according to its respective codes. In addition, NEII fully supports licensing requirements for elevator and escalator mechanics across North America. 

Safety Features Keep Elevators From Moving While Doors are Open

Basic protections from elevators moving while their doors are open have in fact been in place since the 1920s. These simple electromechanical systems, which have continued to be improved over the years, are known as “interlocks” in later elevator codes, and exist on virtually all elevators in operation in the U.S. today. To better protect passengers from possible harm, the 1980 edition of the ASME A17.1 Safety Code for Elevators and Escalators implemented a provision that would lock the elevator car doors (door restrictors) when the car was more than 18 inches above or below the floor. This distance was recently changed to 7 inches. 

In 2000, the first harmonized edition of the ASME A17.1/CSA B44 code for new elevator installations was published it has incorporated the latest advances in technology, making additional protection possible and providing redundant protections against unintended elevator car movement. Elevators installed under the 2000 and later editions of the code contain these safety features:

• A means to detect unintended car movement with the doors open  due to a failure in the drive machine, motor, brake, gearing, control system, hydraulic pressure, etc. that will immediately stop the car;
• An independent, secondary emergency brake that is activated when unintended car movement is detected;
• Application of this brake when a loss of power is detected; and
• A requirement that the emergency brake be manually reset before the car is permitted to run again, requiring a qualified elevator mechanic to diagnose and correct the problem before the elevator is placed back in service.

For those elevators that predate the safety features introduced in the past 20 years, the ASME A17.3 Safety Code for Existing Elevators and Escalators contains basic requirements for rider safety in these older systems. These include requiring door restrictors and prohibiting the driving machine that moves the car from operating with passengers on the car if the elevator doors are not in a closed position. NEII has consistently advocated for the adoption of the ASME A17.3 within every jurisdiction nationally, to ensure that a designated minimum standard of safety is met, regardless of the age, model or manufacturer of the equipment.

Regular Inspections and Maintenance are Critical

As with any electrical and/or mechanical system, it is critical that elevators be inspected and maintained on a regular basis to ensure that these safety features are functional. The ASME A17.1/CSA B44 Safety Code for Elevators and Escalators prescribes regular maintenance and periodic testing and inspection for all elevators. Of course, their success relies on building owners that retain adequate elevator maintenance, elevator contractors and technicians that are proficient in their work, and jurisdictions that require qualified elevator inspectors to help ensure the safety of the equipment. Proper preventive maintenance plays a critical role in eliminating the potential for equipment malfunctions and addressing any prospective difficulties.

Unfortunately, accidents can still occur even with all of these measures and the protections contained in our safety codes. This is why the NEII member companies remain committed to developing new technology to further enhance passenger protection in both new and old elevators. NEII remains a strong advocate of elevator and escalator safety by continually improving the systems in place to help ensure rider safety, endorsing the adoption of current model codes by local government agencies, and assisting our national and international code-writing bodies in the improvement of rules that affect the installation, maintenance and operation of this equipment.

As elevator technology continues to evolve, these safety codes also encourage the efficient and safe adoption of the latest technical developments, resulting in elevator equipment that remains on the leading edge of safety, innovation and reliability.  

Elevators Are One of the Safest Forms of Transportation

Though elevators are one of the safest forms of transportation with over 18 billion passenger trips per year in the United States alone, following simple guidelines can help further improve passenger safety. We encourage everyone to review these guidelines regularly for more information on these topics. Please visit the elevator and escalator safety pages on the NEII website at www.neii.org.

About NEII

NEII is the premier trade association representing the global leaders in the building transportation industry. Its members install, maintain, and/or manufacture elevators, escalators, moving walks, and other building transportation products. NEII‘s membership includes the six major international companies – Fujitec America, Inc., KONE, Inc., Mitsubishi Electric US, Inc., Otis Elevator Company, Schindler Elevator Corporation, Thyssenkrupp Elevator Company and several other companies across the country. Collectively, the NEII members represent approximately eighty percent of the total hours worked within the elevator and escalator industry, employ more than 25,000 people in the U.S. and indirectly support hundreds of thousands of American jobs in affiliate industries. 

For more information about NEII, please visit www.neii.org.