UNDERSTANDING SEISMIC DESIGN FOR SUSPENDED CEILINGS

Ceilings come in all shapes, sizes and designs, and depending on a range of factors, the seismic design may change to ensure they are structurally sound in the event of an earthquake. 

The role of a seismic engineer is to determine the best restraining method for the ceiling, while taking into consideration the aesthetic and performance requirements of the architect, and the practical aspects of construction. It’s helpful for architects and designers to understand the approaches for seismic design so these factors can be considered in their material choice and overall design.

What do engineers consider when they design for seismic events? 

Suspended Ceiling Design Options 

Ceilings must be designed to withstand both the static loads, including their own weight and any lighting or electrical equipment and any dynamic loads that can act on them, such as the movement caused in an earthquake. 

When engineers consider these loads, there are three methods they commonly apply for the seismic bracing of suspended ceilings. These include the 

1. Fix and Float method which attaches two adjacent edges of a ceiling to the surrounding walls and leaves the other two free to move horizontally. 
2. The seismic gap method splits the ceiling into smaller areas allowing independent movement of the different sections. 
3. Finally, when perimeter fixing is not an option, the ceiling can be braced to the structure above.

You can read more detail about how the design of the ceiling impacts the method chosen in our article ‘Seismic Bracing of Suspended Ceilings; 3 Common Methods’.

Compliance with Building Codes

When engineers design ceilings for seismic loads, they must meet the New Zealand Suspended Ceiling Standard. These standards have been reviewed and were republished in 2020, with a number of additions that have changed current industry practice. For a review of the changes you can read our overview of the new suspended ceilings standard.

Perimeter design considers how the perimeter will connect two different interior elements and how this connection will perform when subjected to lateral loads due to seismic movement. Standardising perimeter design might seem like the fastest approach for architects. However, this can add time and cost to a project when the design is over engineered. Our article What Architects Need to Know about Perimeter Design discusses the common methods for ceilings, how much a perimeter should move, and when each method should be considered.

If you have a project that requires seismic design for ceilings, partitions or racking, get in touch today to find out how our team can help.