As buildings become more complex, the need for architects and other designers to understand specialized structural engineering topics increases. A century ago, architectural and structural drawings were one and the same. Today, however, a structural design may involve several structural engineering firms and other specialists, including fire and life safety consultants. As principal designers, architects must often oversee these varied, and often complicated, disciplines.
Structural fire protection remains one of the most misunderstood aspects of building design, even among structural engineers themselves. I recently contributed a chapter to a new guidebook for students and professionals in the AEC fields, to illustrate how structural fire protection affects building design. It is outlined in this blog post.
ARCHITECT’S GUIDEBOOK TO STRUCTURES
To help architects manage growing complexities and partner with project teams, a recent series of practical guidebooks look to outline structural engineering principles in a practical and comprehensive way. Issued by academic publisher Routledge (available here) and led by Paul McMullin – a founding partner of Ingenium Design in Salt Lake City, UT, and adjunct professor at the University of Utah – the Architect’s Guidebook to Structures series covers a wide range of principles, beginning with the basics of structural systems and building up to complex design considerations.
I contributed a chapter on structural fire protection to the latest book in the series, Special Structural Topics, which covers design for blast, fire effects, vibrations, sustainability, and other special considerations. Structural fire protection is often viewed by designers as a nuisance. However, this area represents one of the most promising opportunities for designers to provide value-added services to project stakeholders. In the chapter, we seek to dispel common misconceptions about the topic and promote key opportunities in the field of structural fire protection. The chapter begins by exploring the reasons why we insulate structures and the effects of fire on those structures. From there, it examines the two sanctioned structural fire protection design options (standard fire resistance design and structural fire engineering) and takes a glimpse into the future of structural fire protection.
FIRE PROTECTION DESIGN
Uncontrolled fires in engineered buildings occur very infrequently, but their consequences can be severe. When fire heats a structure, it experiences thermal effects that are not contemplated by conventional structural engineering design. Under these conditions, the functionality of building safety systems assumes the structural system will remain stable. In light of this, it is natural to ponder the question: ‘Do building codes require that structures be designed to perform adequately under fire?’ Surprising to many, the answer is ‘No.’ Instead, structures typically rely on applied insulation to reduce their heating, with the hope of mitigating fire risk to an acceptable level (per standard fire resistance design or ‘prescriptive design’). This is unlike our consideration of hurricanes and earthquakes, in which structures are engineered to withstand these natural phenomena.
As an alternative to standard fire resistance design, structural fire engineering explicitly evaluates the demand and capacity of structural systems under fire loading. Within this framework, the demand on a structural system under fire loading can be reduced by rationally allocated structural insulation, control of fuel loads, or other fire exposure mitigation techniques. Also, the capacity of a structural system to endure fire effects can be increased by means of specific member sizing, connection detailing, and other measures to enhance structural robustness with respect to explicit performance objectives.
The discussion in the guidebook helps architects to proactively handle structural fire protection issues as they arise, before they can derail their overall design aspirations.
Comparison of structural fire protection design options
A GROWING TREND IN THE U.S.
Structural fire engineering approaches are much more prevalent in Europe than the U.S. However, SGH and others in the industry have helped usher in a growing movement to facilitate a similar level of acceptance and use in this country. Encouragingly, the 2016 edition of ASCE/SEI 7 explicitly permits the use of structural fire engineering in accordance with its new Appendix E (Performance-Based Design Procedures for Fire Effects on Structures). Notably, the inclusion of Appendix E in ASCE/SEI 7 marks the first time that fire effects are considered as an explicit design load condition in a U.S. structural engineering standard (as described in ENR and Fire Protection Engineering magazine). We envision that the new Appendix E, along with the prospective ASCE/SEI Manual of Practice, will help legitimize the field of structural fire engineering in the U.S., and ease the reluctance of stakeholders to adopt this approach for building projects.
I am thankful for the opportunity to contribute to this series, and hope that this guidebook will provide new insight on structural fire protection and assist architects in their ongoing pursuit to design better buildings.
To learn more about this topic, read the related Structural Fire Engineering topic brief or the recent article in The Structural Engineer, “Developments in structural fire protection design – a US perspective” (subscription required).
Kevin LaMalva is a registered fire protection engineer and civil engineer with Simpson Gumpertz & Heger (SGH). He chairs the American Society of Civil Engineers’ Structural Engineering Institute (ASCE/SEI) Fire Protection Committee, and is member to numerous industry committees that conduct research and develop standards for structural fire safety. As co-author of the new Appendix E section in ASCE/SEI 7 (Minimum Design Loads and Associated Criteria for Buildings and Other Structures) and editor of the prospective ASCE/SEI Manual of Practice (Structural Fire Engineering), Kevin provides contemporary insight on this important subject. He was named an ENR Newsmaker for his efforts to advance the practice of performance-based structural fire engineering.