Canadian Earthquakes: Specifying seismic support for non-structural building components

Methods of selecting seismic restraints
The adequacy of seismic restraints for OFCs in any particular application may be evaluated by using analytical or prescriptive methods (or a combination of the two), or employing seismic qualification testing methods. These methods may be applied to both new and existing restraints.

This is important because it gives the designer options in designing or selecting restraint systems that are appropriate for a given area or seismic zone.

Prescriptive method
Prescriptive methods are applicable only to certain types of OFCs. These procedures are based on sound engineering standards and practices, as established by the appropriate industry associations. This means there is no need for analysis or engineering calculations beyond basic information for choosing the appropriate mitigation action in accordance with published standards. Examples include the Ceilings and Interior Systems Construction Association (CISCA) standards covering suspended ceilings and the Sheet Metal and Air-conditioning Contractors National Association (SMACNA) standards for support of ductwork and piping.

With the use of prescriptive-type standards, the restraint details can be selected directly from manufacturer details and information referencing the appropriate standards by sector.

Analytical method
The analytical method is the direct opposite of the prescriptive path. It involves engineering specifically for the OFC. Forces and displacements are introduced in the OFCs by the movement of the buildings when subjected to earthquakes. These forces and displacements can be calculated by one or more of the following analytical methods:

• simplified: approximate methods based on an equivalent static force analysis approach; and
• refined: methods dealing with dynamic behaviour of the building and with varying degrees of complexity (used where there is a direct impant from the OFC onto the structure of the building).

Where do we go from here?
The big question becomes, ‘How can I apply seismic restraints for non-structural components to specifications?’ In research for this article, this author has found a section from the U.S Government of Veteran Affairs labeled Section 13 05 41–Seismic Restraint Requirements for Non-structural Components. Looking at the 2016 edition of MasterFormat, perhaps the most appropriate number for non-structural components would be a mix of both. In other words:

• 13 48 53−Manufactured Seismic Control Components; and
• 13 48 63−Fabricated Seismic Control Assemblies.

If one is looking for a specific section for non-structural components, then maybe creating new sections is the way to go:

• 13 48 05−Common Work Results for Sound Vibration and Seismic Controls; and
• 13 48 50−Seismic Control Requirements for Non-Structural Components.

While research continues, this author would love to hear from readers about their own experiences. How do you specify seismic restraints for non-structural components? In your province, are there special requirements from your AHJ, or the provincial or local associations?

Conclusion
The risk associated with the failure or damage of any operational or functional component during an earthquake depends on far more than simply a building’s vulnerability to strong shaking and differential movement of the supporting structure. As a specification writer, this author believes it is important to have good knowledge of what information is needed prior to the start of the project. It would be appropriate to begin with a good plan:

1. Set up a seismic risk plan for the project, including all the performance requirements and seismic information required to perform calculations. (This can be done by having a good master specification setup. Create new Section 13 48 05−Common Work Results for Sound, Vibration, and Seismic Controls.)

2. Know which components are within the realm of the contract between the owner and consultant. Is this a shell building, tenant improvement, or both?

3. Confirm whether the owner intends to extend any of the seismic restraint design of OFCs to one of the prime consultants outside of the main contract.

4. Verify all seismic restraint carried under MasterFormat Divisions 20 to 28.

5. Ensure structural drawings have notes pertaining to seismic design of non-structural components—all work for designing seismic restraints is outside the structural scope.

Jeff Halashewski, Dipl Arch Tech, is a specifications writer for the Edmonton office of DIALOG. He is a member of the executive for the CSC Edmonton Chapter, and also a member of the Canadian Association of Earthquake Engineering (CAEE). Halashewski has 17 years of experience in institutional, commercial, and industrial buildings, and has worked on projects that involved seismic restraint of non-structural components. He can be reached at jhalashewski@dialogdesign.ca.