By Leo Cannyn, PMP, PE, ENV SP,
Principal Project Manager,
Beryl Engineering & Inspection
One of the most severe environmental conditions for a structure is fire, which happens every 93 seconds. In 2021, there were 1.3 million fires in the U.S., per the National Fire Protection Association.
Success relies heavily on the engineer’s ability to work within the prescriptive constraints of the building codes and standards while applying best engineering practices to achieve the project goals. This is what is referred to as performance-based structural fire design.
An accidental fire in a home or commercial building can result in the failure of various structural components. Therefore, appropriate structural fire design methods are critical in the design of buildings and built infrastructure. Thankfully, the structural engineering community has become more involved in the structural fire protection practice. Over the last five years, the field has become a fast-growing segment and is a much-needed practice.
What is Performance-Based Structural Fire Design?
Performance-based structural fire design (PBSFD) utilizes engineers with experience to develop a design plan that goes beyond just making the building resistant to fire. Introduced in ASCE 7-16, Appendix E, PBSFD is an approach that permits the evaluation of a structure’s ability to meet specific performance objectives under a variety of realistic design fire scenarios. It is the application of science and engineering to design fire protection.
By using physics-based models of fire scenarios and their effects on structural and nonstructural building elements, engineers no longer focus on building construction, but how they want the building to perform. Additionally, structural engineers take into account the specific characteristics of a building rather than utilizing a checklist found in prescriptive building and fire codes that may not address a building’s unique characteristics.
Prescriptive Codes Work Together with Performance-Based Design
Prescriptive codes work well when followed properly in each application. Additionally, performance-based design adds much-needed flexibility to existing prescriptive requirements. PBSFD permits more freedom than conventional prescriptive methods. They allow designers to answer the “what if” questions and evaluate alternative fire suppression systems. When thinking beyond traditional prescriptive solutions, creativity and innovation can take place using both new and existing materials and systems.
The intent is not to use one without the other. Prescriptive codes typically apply a minimum 10 percent safety factor. With performance-based design, each situation is based on potential uncertainties and evaluated on a project-by-project basis.
Performance-Based Fire Design Adds Value
Structural engineers with fire design experience have an in-depth understanding of fire science, construction materials, and good building design practices. Specifically, an experienced structural engineer can evaluate fire risk and develop practical, performance-based design solutions to fire-related engineering problems. They can develop designs that respond to resilience, robustness, and sustainability needs.
Engineers with performance-based fire design experience can:
Evaluate fire risk, consider structural integrity, and suggest alternative safety methods to improve structural efficiencies.
Emphasize science, engineering, calculation, and modeling methods to create cost-effective designs without compromising safety.
Help deliver more resilient structures that meet the project’s identified goals and objectives.
Performance-based fire design is possibly one of the most significant investments in any building leading to informed performance in a potential fire, a better alternative to assumed performance.
However, it’s not enough for the engineer to be knowledgeable and experienced. The most qualified think outside the box and provide creative yet safe solutions in ways that code-writing authorities have yet to consider. The result is the ability to problem-solve and preserve the building’s structural integrity during a fire.