Fire Resistance of Structural Members and Assemblies

Published

March 1, 2023

Author(s)

Matthew Hoehler

Abstract

The selection of building materials and the design of the details of construction always play an important role in overall building fire safety. Two important fire safety considerations regarding the building structure are to minimize the likelihood of collapse of the structural frame during a fire and to ensure that fire barriers remain intact to prevent ignition and fire spread to adjoining spaces. However, there is increasing awareness in the engineering and fire safety professions that structural response in the cooling phase of a fire as well as the post-fire condition of a structure can be relevant performance objectives. The following are the three general approaches to structural frame and barrier design for fire resistance: 1. Fire resistance testing based on standardized procedures, 2. Analytical calculations or prescriptive requirements to establish a fire resistance rating equivalent to standard fire test exposure and acceptance criteria, and 3. Structural fire engineering based on real fire exposure and structural system performance. The traditional method of treating the structural aspects of fire protection is through building code requirements for structural members and assemblies based on ratings determined through standardized fire resistance tests or established using equivalent fire resistance ratings. Classification of building construction with regard to fire resistance requirements is an approach that has the principal advantage of being relatively easy to incorporate into the design process and to administer from a code enforcement standpoint. It has the major disadvantages of being unable to represent the performance of the structural member or fire barrier under the broad range of fire loads to which it may be exposed and the boundary conditions imposed by the structural system. The fact that code compliance alone may not be sufficient to ensure performance success of barriers or the structural system in some fire scenarios or to achieve project-specific performance objectives required by an owner, such as property protection or business continuity, has motivated the advancement of performance-based design procedures for fire effects on structures in recent years. This chapter deals primarily with traditional methods to establish fire resistance ratings for structural members and assemblies. It first provides details on fire resistance test procedures followed by illustrative historical fire resistance ratings for building construction and references to current sources for ratings. It then introduces methods of calculating equivalent fire resistance ratings based on standard fire testing exposure and acceptance criteria. The chapter concludes with discussion of the behavior of common building materials at elevated temperatures.

Citation

Fire Protection Handbook

Publisher Info

National Fire Protection Association (NFPA), Quincy, MA

Pub Type

Books

Download Paper

Local Download

Keywords

beam, ceiling assembly, column, fire barrier, fire endurance, fire resistance, fire test, floor assembly, gypsum, partition, reinforced concrete, roof assembly, structural assembly, structural frame, structural steel, wall, wood

Citation

Hoehler, M. (2023), Fire Resistance of Structural Members and Assemblies, National Fire Protection Association (NFPA), Quincy, MA, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932140 (Accessed May 7, 2024)