Earthquakes are difficult to predict. But in the US, significant effort has been made to ensure buildings can withstand earthquakes when they do occur. Because of this, modern and retrofitted buildings which are structurally resilient, tend to perform relatively well in earthquakes. What is less clear is how the contents and non-structural building components should be secured, and who is responsible for ensuring building contents are safe during earthquakes.
Why is seismic restraint needed?
According to FEMA, the majority of damage in today’s earthquakes is from the shaking of contents in or attached to buildings. These nonstructural components generally make up around 80% of a building’s construction cost.
Nonstructural damage causes both life safety and economic consequences. Examples include:
Life Safety
| Economic
|
According to the International Building Code (IBC) if a building is in a moderate to high seismic region, the building contents must be considered in seismic design and designs must be stamped by a professional engineer. Restraining contents is especially important for hospitals, fire/police stations, schools and other critical structures, as IBC puts these structures in heightened risk categories.
Typically, IBC requires “seismic restraint,” meaning that a component must have a positive connection to the structure (slab, beam, wall). A simple example would be a bookshelf anchored to a concrete slab or a storage rack tied back to wall studs.
Usually, seismic testing is not required except in certain cases when a component needs to function during or immediately after an earthquake, such as a backup generator for a hospital.
What items need seismic restraint?
IBC explicitly lists several nonstructural components that must be considered in seismic design. A few examples are:
Architectural
| MEP
| Furniture & Fixtures
|
Who is responsible for enforcing the Code provisions for nonstructural components?
The responsibility for enforcing the earthquake safety of building contents, especially those installed after construction is not always clear. Is it the building manager’s responsibility? Architect? Engineer of record? Contractor? Manufacturer?
Certain city governments in California have started to strictly enforce these provisions through special inspections, even requiring manufacturers to provide stamped design drawings. It is only a matter of time before other city governments in moderate seismic regions follow suit.
What can you do to ensure your building is safe?
Earthquakes will occur in the future, and it’s important to consider how to mitigate the damage as much as possible when they do occur. In this vein, FEMA provides great resources and checklists on both seismic restraint of building contents and incremental seismic rehabilitation/retrofit. FEMA’s National Earthquake Hazards Reduction Program (NEHRP) provides funding to help with this effort.
Our Structural Team is experienced in navigating the complex codes and technical resources relating to seismic design. Engaging a structural engineering expert can ensure you are keeping contents – and therefore building occupants – safe and secure in the event of an earthquake.