Structural Fire Protection is Critical to the Stability of Structures in Fire
Structural fire protection includes the insulation materials, coatings, and systems used to prevent or delay fire-induced temperature rise in structural members in buildings. It falls into the general class of passive fire protection that typically supplements active fire protection (fire alarms, fire suppression systems, human interventions, etc.), as required by the building codes. Structural fire protection for walls, columns, and floors can be provided in varied forms, different materials and products, such as lightweight or higher density spray-applied fire resistive materials, gypsum board, intumescent/mastic coatings, concrete and masonry. Performance, weight and cost are the three key design selection factors. The analysis-design of fire protection can be performed in one of two ways: prescriptively or by means of performance-based engineering. The conventional prescriptive approach relies on fire resistance rated assemblies developed from standard furnace tests conducted in accordance with the long-established ASTM E119 criteria. The selection of the fire protection material type, product, thickness, and its installation details will depend on the particular assembly design selected for the required rating time of the fire resistive construction.
Desire for a more refined solution, exposed/unprotected construction, retrofit or upgrade of an existing building, or other unique project considerations may be the predominant reasons for use of the alternative performance-based engineering approach to demonstrate adequate structural fire integrity for the particular design conditions. This alternative approach to fire resistive design requires use of advanced analyses for the site-specific natural fire scenario, computation of its heating effects on the structural members and the resulting structural response under gravity load. It may be applied to an entire building or structure, but to date, has usually been limited to specific structural elements (such as individual types of columns) or subassemblies (such as floors or trusses). A design-basis fire exposure will often be developed and used for such cases in lieu of the standard ASTM E119 fire curve. The objective of this type fire resistive analysis is to demonstrate that the structural components or framing of interest will not collapse during the worst-case fire exposure expected for the building occupancy. Performance-based design typically entails the use of fire modeling, heat transfer and structural analyses.
Applications for Non-building Structures
Fire protection is often required for various other special or non-building structures, such as petrochemical refineries, power generation facilities, propane tanks, rail and tunnels (transportation), and airport and aviation control towers. Many of these rely on fire test standards that are substantially different from the ASTM E119 provisions for buildings and specific to the hazards and environment particular to the use conditions. The fire exposures expected for these cases is more severe than for buildings. Similar to buildings, JENSEN HUGHES has consulted on numerous projects to develop and implement suitable fire protection for fire safety in such non-building structures. Due to the greater fire threat and severity at the sites, as well as needed performance attributes in outdoor service and weathering conditions, and potentially other related concerns, the products and systems used will usually be more robust and expensive than is typical in building construction.