FEMA E-74 Chapter 6.2 Nonstructural Component Examples

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6.2 Nonstructural Component Examples

The tables in this chapter and the checklists and risk ratings in the appendices all have similar numbering; illustrated examples are provided for many, but not all, of the components listed. The components addressed herein have been grouped under three major headings:

  • Architectural
  • Mechanical, Electrical, and Plumbing (MEP)
  • Furniture, Fixtures, and Equipment (FF&E) and Contents

Each of these three major categories includes a number of subcategories. The checklists and risk ratings in Appendix D and Appendix E address all of the subcategories; examples are also provided here for each of the components listed. This document has been prepared as a web-based document with the idea that additional examples may be added in the future.

The nonstructural component examples typically consist of the following elements:

  • Typical Causes of Damage: A brief description relevant to the particular item.
    • Damage Examples: The photographs presented here cover a variety of situations and have been taken over a 39-year period. Photographs from the 1971 San Fernando Earthquake generally show damage to components that were not restrained, while some of the more recent photographs depict damage to components that appeared to be braced or anchored but whose bracing and anchoring details were apparently inadequate to resist the severity of the shaking. Photos from the 2010 Haiti, Chile, Eureka, California, Baja California, and Christchurch, New Zealand Earthquakes have been included, illustrating the ongoing problems with nonstructural performance.
       
  • Seismic Mitigation Considerations: A description of issues relevant to the mitigation of the particular item.
    • Mitigation Examples: The photographs presented here show braced and anchored components. Most are examples of properly anchored components; some show improper installations with an explanation of the problem(s).
    • Mitigation Details: Usually one or more suggested details that can be used to reduce the seismic vulnerability of the item. These details are not engineering drawings; in general, they have been drawn with shading to represent the appearance of the properly anchored item. The protection measures or seismic anchorage details are classified as Non-Engineered (NE), Prescriptive (PR), or Engineering Required (ER); these terms are described below.

6.2.1 Typical Mitigation Details

Non-Engineered (NE) Details

These are simple, generic seismic protection details that do not require engineering design to determine the requirements. Some examples of types of nonstructural protection that can be designed and implemented without an engineer include:

  • Restraints for tenant-supplied movable equipment and furniture
  • Restraints for cabinet doors and drawers
  • Restraints for shelved items

For these types of elements, generic restraint details are usually sufficient to provide adequate protection. The earthquake forces on these elements are generally small compared to the strength of the restraint methods that are usually recommended. Together with the installation guidelines at the end of this chapter, enough information is provided to enable someone without specialized expertise in the field to install the restraint shown using common tools and readily available materials. Many vendors now sell off-the-shelf seismic restraints that can be used for these Non-Engineered details; check the internet for available hardware.

There are limitations to the use of non-engineered seismic protection measures: this method should only be used for elements that are relatively lightweight. Non-engineered restraints should not be used for elements that are considered critical, such as emergency power systems, large inventories of hazardous materials, or in hospitals, where immediate postearthquake operations are desired.

Prescriptive (PR) Details

These mitigation solutions rely on standard restraint details that have been previously developed and can be implemented without the need for an engineer. Together with the installation guidelines at the end of the chapter, enough information is provided to enable a contractor or skilled individual to install the restraints shown.

Examples of elements that can be mitigated by prescriptive methods include:

  • Water heaters, up to 100 gallons capacity
  • Suspended acoustic ceilings, up to 4 pounds per square foot in weight

While the underlying design of the prescriptive details has been reviewed by experienced engineers, some judgment is required on the part of the user to ensure that their use is appropriate for the situation. For instance, the ceiling bracing detail shown may not be appropriate for ceilings weighing more than 4 pounds per square foot; the user will need to verify the weight of the ceiling in question.

Engineering Required (ER) Details

Bracing, anchorage, or restraint details for these components require design by an engineer or design professional experienced in the seismic design of nonstructural elements. The details provided in this document are schematic details showing common solutions for the components in question. These figures do not contain sufficient information for installation; they are provided primarily as an illustration of the required scope of work and the necessary elements for proper seismic restraint. Information regarding the size and spacing of bolts, type and size of steel shapes, appropriate configuration, required restraint capacity, and capacity of the structural elements to which they are attached needs to be determined by an engineer, or in some cases, by a specialty contractor.

The designation Engineering Required has been used for components for which the non-engineered approach is most likely to be ineffective. The recommendation of this guide is that design professionals be retained to evaluate the vulnerability of these components and to design appropriate anchorage or restraint details, particularly when safety is an issue. As stated earlier, this recommendation may apply to all components of specialized facilities such as hospitals and emergency operations or communications centers, where interruption or loss of function is unacceptable. Recent experience has shown many instances in which fire sprinkler and other water lines, HVAC equipment, emergency generators, water tanks, ceilings, parapets, glazing, and such were damaged when subjected to severe shaking and failed to perform as expected. The lesson learned from this experience is that the protection of many items, particularly MEP equipment and architectural components in facilities that are expected to be functional after an earthquake, or could be immediately restored to operation by routine means, is a complex undertaking that should be addressed by engineers and architects with specific expertise in this area. As a result, most MEP systems and architectural components have been given the designation Engineering Required. Several of the items listed under FF&E and contents have also been given this designation.

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Last Updated: 
07/24/2014 - 16:00
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