5_Ch07_Fire-Related+Properties

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Lecture on Fire-‐Related Proper7es of Materials

•  World trade Center

Fire resistant behavior

Introduc7on

FIRE-‐RELATED PROPERTIES

Introduc7on to Fire Safety

•  Because of sustained improvements in fire safety and zoning regula7ons and advances in fire detec7on and suppression equipment used in buildings, fires today are generally limited to individual buildings or a small group of buildings.

•  Fire con7nues to be the single largest killer of building occupants in the United States.

•  Because fire is the biggest hazard to life safety in modern buildings, building codes recognize this fact by making fire protec7on an important objec7ve.

Fire-‐Safe Construc7on

Four floors of the First Interstate Building in Los Angeles, California, guPed with fire. The building is s7ll standing and is in service. Its survival is ascribed primarily to its fire-‐safe construc7on.

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Factors That Affect Fire Safety in Buildings

•  Fire safety in buildings is a func7on of several variables, which may be grouped under the following three categories: 1.  Architectural design 2.  Fire protec7on systems 3.  Public educa7on

Factors That Affect Fire Safety in Buildings – cont’d

Factors that affect fire safety in buildings. In this chapter, we focus only on passive protec7on systems.

Fire Code and Building Code


Fire Code and Building Code

•  In addi7on to the building code, a building is regulated by the jurisdic7on’s fire code .

•  The regula7ons that cover aspects of fire safety in a building during its use and occupancy are included in the fire preven,on code, or simply the fire code.

•  The building code and the fire code are two arms of a jurisdic7on’s building safety ordinances.

•  They are enforced by the jurisdic7on’s building official and fire official, respec,vely.

Combus7ble and Non-‐Combus7ble Materials


Combus7ble and Non-‐Combus7ble Materials

•  The dis7nc7on between a combus7ble and a noncombus7ble material is generally, although not always, obvious.

•  Non-‐combus7bility (ASTM E136 Test) – The ASTM E136 test is applicable only to elementary materials, not to composites, laminated, or coated materials.

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ASTM E136 Test

ASTM E136 test setup to determine whether a material is combus7ble or non-‐combus7ble.

Gypsum Board

A material with a noncombus7ble core but with a combus7ble lamina7on less than or equal to 1/8 in. (3 mm) thick is regarded by the building codes as a noncombus7ble material.

Non-‐Combus7bility of a Material and its Ability to Withstand Fire

•  Non-‐combus7bility refers only to the fact that a noncombus7ble material will not add fuel to the fire.

•  Non-‐combus7bility is not related to the ability of the material to withstand fire.

Products Given Off in a Building Fire


Products Given Off in a Building Fire

Products of combus7on in a building fire.

Causes of Death in a Building Fire

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Fire-‐Rated Assemblies and Compartmentaliza7on of a Building


Fire-‐Rated Assemblies and Compartmentaliza7on of a Building

Compartmentaliza7on of a building by fire-‐rated assemblies. A fire-‐rated assembly may be either a ver7cal or horizontal.

Requirements of a Fire-‐Rated Assembly

•  The concept of compartmentaliza7on assumes that the boundary elements of the compartment (walls, floors, and roofs) will func7on as barriers against the spread of fire to adjacent compartments of the building. We refer to such barriers as fire-‐rated assemblies . To meet this criterion, a fire-‐rated assembly must sa,sfy the following three requirements: –  Perform structurally without collapse (i.e., sustain design loads

throughout the dura7on of the fire) –  Remain fire-‐7ght (i.e., no cracks during the dura7on of the fire).

•  The purpose of this requirement is to ensure that smoke and flames will not spread to adjacent compartments.

–  The temperature of the unexposed face of a fire-‐rated assembly during a fire should be so low that the heat received by radia7on and (or) conduc7on through the assembly will not ignite combus7bles in adjacent compartments.

Types of Construc7on


Types of Construc7on

•  Building construc7on is classified as Type I, II, III, IV, or V, based on fire ra7ngs of the various cri7cal assemblies of the building.

•  The higher the fire ra7ng of these assemblies, the more fire resis7ve the type of construc7on.

Types of Construc7on – cont’d

•  The five types of construc7on are categorized under three groups: 1.  Noncombus,ble group —consis,ng of Types I (A and B)

and Types II (A and B). –  All envelope and structural assemblies must be of noncombus7ble materials (concrete, steel, or masonry).

2.  Noncombus,ble/combus,ble group —consis,ng of Types III (A and B) and Type IV.

–  The exterior walls must be of noncombus7ble materials, whereas other assemblies of the building may be of combus7ble or noncombus7ble materials. A combus7ble type of construc7on generally refers to one whose structural frame consists of wood or wood-‐based products.

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Types of Construc7on – cont’d

3.  Combus,ble group —consis,ng of Types V (A and B). In these types of construc,on. –  All envelope and structural elements may be of combus7ble or

noncombus7ble materials.

Notes: 1 Nonbearing exterior walls and interior par77ons in non-‐combus7ble group (Types I and II) must be of non-‐combus7ble materials. 2 Minimum fire ra7ng of exterior nonbearing walls is a func7on of separa7on distance (distance measured from the wall to the center of the street or to line between two adjacent lots). If the separa7on distance is greater than 30 f, the walls need not have any fire ra7ng. 3 Minimum fire ra7ng of interior par77ons depends on the purpose they serve, e.g., corridor walls, tenant separa7on walls, guest room separa7on walls in hotels or motels, and so on.

Reference: Interna7onal Building Code (2009) published by the Interna7onal Code Council.

Example – Type II(B) Construc7on

An example of Type II(B) construc7on. In this building, the load-‐bearing walls are of masonry, and other structural elements (columns, roof joists and roof deck) are of steel. Therefore, it is a noncombus7ble type of construc7on—Type I or Type II. However, because the roof assembly is not protected against fire, its fire ra7ng is (much) less than 1 h, qualifying as a nonrated assembly. Therefore, it is a Type II(B) construc7on.

•  The wood members are typically protected against fire with 12-‐in.-‐thick gypsum board on both sides, which gives the wall, floor, and roof assemblies a fire ra7ng of nearly 40 min.

•  Since the fire ra7ng is less than 1 h, such assemblies meet the requirements of Type V(B) construc7on—a nonrated construc7on

Example – Residen7al Wood Frame Construc7on

Floor Assembly (Type V Construc7on)

Floor assembly in a typical wood light frame construc7on (Type V construc7on) illustrates concealed spaces that occur in walls, floors and roofs with such construc7on.

•  An example of heavy 7mber construc7on—Type IV.

•  No7ce heavy sec7ons of wood with no protec7ve covering and no concealed spaces.

Example – Heavy Timber Construc7on

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•  A cast-‐in-‐place reinforced concrete building (under construc7on).

•  It is not possible to precisely judge its type of construc7on without examining the construc7on drawings of the building because the fire ra7ng of a cast-‐in-‐place reinforced concrete building is a func7on of the dimensions of the structural members and the concrete cover over steel reinforcement.

•  However, such a building is likely to be a Type I(A) or Type I(B) construc7on, probably Type I(A).

Example – Cast-‐in-‐Place Concrete Determining the Type of Construc7on

Determining the Type of Construc7on – cont’d



Fire-‐Stopping of Penetra7ons and Fire-‐Sealing of Joints


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Fire-‐Stopping of Penetra7ons and Fire-‐Sealing of Joints

A typical fire-‐stopping around a penetra7on in a floor generally consists of high-‐density mineral wool pressure fiPed into the void, followed by a semi-‐liquid, fire-‐resistant sealant troweled over mineral wool packing.

Fire Containment Assembly (Curtain Wall)

Fire containment assembly in a curtain wall consists of a fire-‐rated spandrel and a fire-‐rated seal between the wall and floor.

Fire-‐Test Response Characteris7cs of Interior Finishes


Fire-‐Test Response Characteris7cs of Interior Finishes

•  Another important fire-‐related property of an assembly is its ability to resist the spread of fire within the compartment of origin. This property is a func7on of the – Surface burning behavior of interior finish materials

– Toxicity and density of smoke generated by the burning of finish materials

FSI and SDI

•  The flame-‐spread index (FSI) is a measure of the rate at which flames spread on the surface of an assembly or material used as an interior finish.

•  The smoke-‐developed index (SDI) measures the visibility through the smoke resul7ng from burning assemblies or materials used as interior finishes. The lower the visibility through smoke, the greater the SDI value.

FSI Values of Selected Materials

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Classifica7on of Interior Finishes

General building code requirements for the class of interior finishes.

Importance of Ac7ve Fire Protec7on


Importance of Ac7ve Fire Protec7on

•  Ac7ve fire protec7on (through the use of automa7c sprinklers) is an important part of fire-‐safe construc7on.

•  Building codes encourage the use of automa7c sprinklers by allowing greater area and height for a building that is sprinklered in comparison with a building that is not sprinklered.

•  For some occupancies, however, the use of automa7c sprinklers is mandated by building codes, even when the passive fire protec7on provided in the building is of a high order (e.g., Type I(A) or Type I(B) construc7on).

Importance of Ac7ve Fire Protec7on – cont’d

•  The 2009 Interna7onal Residen7al Code (IRC) requires that all new one-‐ and two-‐family dwellings and townhouses in the United States constructed afer January 1, 2011, shall be equipped with automa7c sprinklers in the hope that this will reduce the number of fatali7es in one-‐ and two-‐family dwellings in the United States.

•  This IRC provision is highly controversial among stakeholders because although it has obvious life-‐safety and property protec7on benefits, it also has the drawback of increasing the ini7al construc7on and long-‐term maintenance costs.

•  Consequently, several states have adopted 2009 IRC with the sprinkler mandate, while others have adopted 2009 IRC without the sprinkler mandate.

5_Ch07_Fire-Related+Properties

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