Resilience based design
By Kyle Johnson, PE, SE – Senior Engineer, Structural Engineering | Seattle Office
Building codes have historically taken the design philosophy of protecting against loss of life as the primary objective, without accounting for post-disaster downtime or required retrofits. A building can meet all code requirements and function to safely evacuate people from the building but may still need to be demolished or require significant retrofits to be occupiable after a major event. This downtime after a natural disaster can have significant impacts on the recovery of a community. If residences are not safe for people to live in or offices are out of use for extended periods of time, people and businesses may need to relocate further hindering the recovery.
FEMA and other agencies have recently been evaluating how the building code can be revised to incorporate target “beyond life safety” goals to protect communities from excessive recovery efforts post disaster. These performance targets are aimed to address two factors:
Functional Recovery: “A post-disaster performance state in which a building or lifeline infrastructure system is maintained, or restored, to safely and adequately support the basic intended functions associated with the pre-disaster use or occupancy of a building, or the pre-disaster service level of a lifeline infrastructure system.” (FEMA-NIST, 2021)
Resilience: “The capability of an organization or community to withstand, respond to, and recover from a disaster in order to return its livelihood to a measure of its pre-disaster state in a timely, nondisruptive manner, while also minimizing the consequences of a future hazard event.” (NIST GCR 23-041)
By shifting our target objectives from a collapse prevention/life safety approach to targeted functional recovery-based objectives, we can make our communities more resilient to natural disasters. Figure 1 gives a visual, from FEMA, for expected structural behavior and costs associated with targeting higher building resilience. By targeting a higher performance level, the downtime of a building is lessened as less repair is needed, resulting in less drag on the economy and environment. From this figure, the carbon impact of repairs can also be seen as related to building performance. By better understanding how a building will respond to a natural disaster, the repair time and costs associated with a repair can be greatly minimized.
These higher performance targets can be achieved without significant impacts on the overall cost of the structural system. By incorporating new technologies such as replaceable fuses, small premiums upfront can mean a significant decrease in downtimes post event, benefiting both the property owners and the community at large.
At Coffman, we are well versed in providing guidance for targeted building performance, especially in facilities housing research and development. If your project may be a good fit for incorporating a Resilience Based Design or you would like to learn more, complete the “Contact Us” form linked on this page and one of our design professionals will contact you.