SNB.2.02.01-98 “Fire-technical classification of buildings, building structures and materials”
Fire resistance is an ability building structures resist the effects of fire for a certain time while maintaining operational functions.
Fire resistance is characterized by the fire resistance limit.
Fire resistance limit building structures are characterized by limit states normalized according to temporary characteristics:
Load capacity (R)
Integrity (E)
Thermal insulation capacity (I)
(For example: REI120K0 – the object retains its integrity, load-bearing capacity, thermal insulation capacity for 120 minutes, non-fire hazardous)
By fire danger building structures are divided into 4 classes:
K0) Non-flammable
K1) Low fire hazard
K2) Moderately flammable
K3) Fire hazardous
Depending on the fire resistance limit, 8 degrees of fire resistance are established (1st is best, 8th is worst)
1st degree of fire resistance: load-bearing walls R120K0, internal walls RE150K0, flights and landings RE30K0.
Category A) Explosion and fire hazard – Combustible gases (GG), flammable liquids (flammable liquids) with a flash point of no more than 28ºC, flammable liquids in such quantities that they can form explosive vapor-gas-air mixtures, upon ignition of which a calculated overpressure explosion in a room exceeding 5 kPa. Substances and materials capable of exploding and burning when interacting with water or with each other in such quantities that the calculated excess explosion pressure in the room exceeds 5 kPa.
Category B) Explosion and fire hazard – flammable dusts or fibers, flammable liquids (flammable liquids) with a flash point of more than 28ºС, flammable liquids in such quantities that they can form explosive dust or steam-gas-air mixtures, upon ignition of which the calculated excess pressure of explosions in the room develops, exceeding 5 kPa.
Category B) (Divided into B1, B2, B3, B4) Fire hazardous - flammable liquids (flammable liquids), flammable liquids and difficult to combustible liquids, solid flammable and difficult to combustible substances and materials (including dust and fibers), capable of interacting with burn with water, oxygen, air or with each other.
D1) Combustible gases, flammable liquids (flammable liquids), flammable liquids, solid flammable and difficult to combustible substances and materials used as fuel.
D2) Non-combustible substances and materials in a hot, incandescent or molten state, the processing of which is accompanied by the release of radiant heat, sparks and flames.
Fire barriers
The purpose of fire barriers is to stop the spread of fire.
Fire barriers:
Fire wall - crosses perpendicularly the entire building, starting from the zero mark and ending with the roof, and protrudes above the roof (0.3-0.6) m. Fire resistance limit 150 min.
Fire partition - partitions within one room. Fire resistance limit 150 min.
Fireproof ceilings – resist the spread of fire vertically.
Fire belt - protects so that fire does not engulf the building from the outside.
Fire doors can be metal, wood or upholstered with sheet steel.
Fire hatches.
Fire windows (tempered glass, triplex, reinforced glass)
Tambour-gateway.
Water curtains (deluge system).
Fire curtain.
Evacuation routes.
SNB 2-02-01 “Evacuation of people from buildings and structures in case of fire”
Escape routes serve to ensure the evacuation of all people in the building through emergency exits, without taking into account fire extinguishing equipment and smoke protection.
Exits are evacuation if they lead from the premises:
The first floor - directly to the outside or through the corridor and vestibule, corridor and staircase to the outside.
Any above-ground floor - directly into the staircase or into the corridor leading to the staircase, which has access directly to the outside or through a vestibule separated from adjacent corridors by doors.
Basement or ground floor - directly outside or onto a stairwell, or into a corridor leading to a stairwell. In this case, the staircase must have direct access to the outside, or be isolated from the overlying floors.
To an adjacent room on the same floor, provided with exits, in accordance with points a, b, c.
If a fire occurs, people must leave the building within a time determined by the shortest distance from the fire to the exit outside.
The number of emergency exits from buildings is determined by calculation, but is at least two.
Elevators are not escape routes.
The width of escape routes must be at least 1 meter, doors on escape routes must be at least 0.8 m, and the height must be at least 2 m.
For buildings of 1, 2, 3 degrees of fire resistance, the time for evacuating people from the doors of the most remote premises to exiting outside is accepted:
From premises of buildings of any category with access to a dead-end corridor (0.5 minutes).
External evacuation doors of buildings should not have locks that cannot be opened from the inside in case of fire.
From premises located between two staircases and two external exits:
If it is necessary to install locks on doors, in order to preserve value, it is allowed to install electromagnetic contacts that are activated automatically or manually.
1.22.* The degree of fire resistance, class of structural fire hazard, permissible height (according to SNiP 21-01-97) and floor area within the fire compartment of detached buildings, extensions 1) and inserts should be taken according to table. 4 .
1 An extension is a part of a building intended to accommodate administrative and utility premises, separated from industrial buildings and premises by fire barriers. It is allowed to place (partial) engineering equipment in extensions.
In buildings of IV degree of fire resistance with a height of two floors or more, elements of load-bearing structures must have a fire resistance limit of at least R 45.
In buildings of III and IV degrees of fire resistance, to ensure the required fire resistance limit of load-bearing structures, only structural fire protection should be used.
In buildings of I, II, III degrees of fire resistance for the attic floor, it is allowed to take the fire resistance limit of load-bearing building structures R 45, ensuring their fire hazard class K0, when separated from the lower floors by a fire-resistant ceiling of the 2nd type. In this case attic floor must be divided by fire partitions of the 1st type into compartments with an area of: for buildings of I and II degrees of fire resistance no more than 2000 sq. m, for buildings of III degree of fire resistance - no more than 1400 sq. m. In this case, the fire partition should rise above the roof in the same way as a fire wall.
In the attics of buildings up to 10 floors inclusive, use is allowed. wooden structures with fire protection providing fire hazard class K0.
Table 4
Fire resistance level of buildings |
Structural fire hazard class |
Permissible height, m |
Floor area within the fire compartment, sq. m., with the number of floors |
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1.23.* When designing buildings with a height of 10-16 floors (more than 28 m according to SNiP 21-01-97), additional requirements for these buildings should be taken into account in accordance with SNiP 2.08.02-89 * and SNiP 21-01-97.
1.24.* Extensions of I and II degrees of fire resistance should be separated from industrial buildings of I and II degrees of fire resistance by fire partitions of the 1st type.
Extensions below the II degree of fire resistance, as well as extensions to industrial buildings below the II degree of fire resistance and extensions to premises and buildings of categories A and B should be separated by fire walls of the 1st type. Extensions of the IV degree of fire resistance class C0 may be separated from industrial buildings of the IV degree of fire resistance classes C0 and C1 by fire walls of the 2nd type.
1.25.* Inserts should be separated from production premises fire walls of the 1st type.
Inserts in buildings of I, II degrees of fire resistance of classes C0 and C1, III degree of fire resistance of class C0 are allowed to be separated from industrial premises of categories B, D and E by fire partitions of the 1st type, in buildings of III degree of fire resistance of class C1 and IV degree of fire resistance of classes C0 and C1 - fire walls of the 2nd type.
Buildings should be accepted with a number of floors of no more than two and separated from industrial premises of categories B, D, E by fire partitions with a fire resistance limit of EJ 90 and fire resistant floors of the 3rd type.
The total area of inserts allocated by fire partitions of the 1st type and fire walls of the 2nd type, as well as built-ins and production premises, should not exceed the area of the fire compartment established by SNiP 31-03-01.
1.26. Corridors should be divided by type 2 fire partitions into compartments no more than 60 m long.
1.27. From those located in aboveground and ground floors and corridors without natural light, regardless of their area, and dressing rooms with an area of more than 200 m2 should be provided exhaust ventilation for smoke removal in accordance with SNiP 2.04.05-91 *.
1.28.* In buildings, extensions, inserts and additions, ordinary staircases of the 1st type should be provided, except for the cases specified in clause 1.23.
In buildings of I and II degrees of fire resistance with the number of floors no more than three 50% stairwells it is allowed to provide type 2 with an upper natural light; in this case, the distance between flights of stairs must be at least 1.5 m. In these buildings, the main stairs can be designed open to the entire height of the building, provided that the remaining (at least two) stairs are placed in ordinary stairwells of the 1st type. In this case, lobbies and floor halls in which open staircases are located must be separated from adjacent rooms and corridors by type 1 fire partitions.
1.29. Glazed doors and transoms above them in interior walls stairwells can be used in buildings of all degrees of fire resistance; At the same time, in buildings with a height of more than four floors, glazing should be made of reinforced glass.
1.30.* The cladding and finishing of the surfaces of walls, partitions and ceilings of halls with more than 75 seats (except for halls in buildings of fire resistance class V) should be made from materials of flammability groups not lower than G2.
1.31. Automatic fire alarm should be in separate standing buildings and extensions with more than four floors, in inserts and build-ins - regardless of the number of floors in all rooms, except for rooms with wet processes.
SAMPLE CONSTRUCTION CHARACTERISTICS OF BUILDINGS
DEPENDING ON THEIR DEGREE OF FIRE RESISTANCE
1. Fire resistance level
2. Design characteristics
I
Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete using sheet and slab non-combustible materials
II
Same. It is allowed to use unprotected steel structures in building coverings
III
Buildings with load-bearing and enclosing structures made of natural or artificial stone materials, concrete or reinforced concrete. For floors, it is allowed to use wooden structures protected by plaster or low-flammability sheet and slab materials. There are no requirements for fire resistance limits and fire spread limits for coating elements, while attic wood roofing elements are subject to fire retardant treatment
IIIa
Buildings predominantly with frame design diagram. The frame elements are made of unprotected steel structures. Enclosing structures - made of profiled steel sheets or other non-combustible sheet materials with low-flammability insulation
IIIb
The buildings are predominantly one-story with a frame structural design. Frame elements are made of solid or laminated wood, subjected to fire retardant treatment, ensuring the required limit of fire spread. Enclosing structures - made of panels or element-by-element assembly, made using wood or wood-based materials. Wood and other combustible materials of enclosing structures must be subjected to fire retardant treatment or protected from fire and high temperatures in such a way as to ensure the required fire spread limit.
IV
Buildings with load-bearing and enclosing structures made of solid or laminated wood and other combustible or low-combustible materials, protected from fire and high temperatures by plaster or other sheet or slab materials. There are no requirements for fire resistance limits and fire spread limits for coating elements, while attic wood roofing elements are subject to fire retardant treatment
IVа
The buildings are predominantly one-story with a frame structural design. The frame elements are made of unprotected steel structures. Enclosing structures - made of profiled steel sheets or other non-combustible materials with combustible insulation
V
Buildings, the load-bearing and enclosing structures of which are not subject to requirements for fire resistance limits and fire spread limits
Note. The building structures given in this appendix must meet the requirements of Table. 1 and other standards of this SNiP.
The highest degree of fire resistance is I (mausoleum).
The degree of fire resistance of buildings, the required fire resistance limits PTR of building structures. Fire hazard of building materials
DEGREE OF FIRE RESISTANCE OF BUILDINGS, REQUIRED LIMITS OF FIRE RESISTANCE OF PTR BUILDING STRUCTURES.
FIRE HAZARD OF BUILDING MATERIALS.
For residential buildings, the degree of fire resistance of the building is determined according to SNiP 31-01-03 depending on the height of the building (Table 5). For example, for buildings up to 50 m high with a floor area up to 2500 m2, the fire resistance degree should be I.
Knowing the degree of fire resistance of the building according to the table. 6 of SNiP 21-01-97* “Fire safety of buildings and structures” defines the required fire resistance limits PTR of all building structures.
The fire resistance limit of building structures is set by time (in minutes) until the onset of one or successively several signs normalized for a given structure: for load-bearing structures based on loss bearing capacity R, in min.; for outdoor curtain walls, floor slabs according to E - loss of structural integrity, i.e. until through cracks form, in minutes; for floors, floorings, internal walls according to J - loss of thermal insulation capacity, when on the side of the floor opposite from the impact of the fire the temperature rises on average by 160°C. The required fire resistance limits of PTR building structures are established according to R; RE; REJ, they are given in table. 6 (SNiP 21-01-97).
To provide fire safety the following condition is required: the actual fire resistance limit of structures (Pf) (see Table 2) must be equal to or exceed the required fire resistance limit (Ptr) according to the standards: (Pf>Ptr).
A comparison of the fire resistance limits Ptr and Pf is made according to the form presented in table. 1. For load-bearing elements of a building, the fire resistance limit is determined according to R, according to RE - for elements without attic floors, according to REJ - for floors, including basements and attics, according to E - for external non-load-bearing walls.
The fire resistance limit when filling openings in fire barriers (doors, gates, glazed doors, valves, curtains, screens) occurs when integrity E is lost; thermal insulation capacity J; achieving the maximum heat flux density W and (or) smoke and gas tightness S. For example, smoke and gas tight doors with more than 25% glazing must have a fire resistance rating of EJWS60 for the first type of filling; EJSW30 - for the second type of filling the opening and EJSW15 - for the third type of filling the opening within fire limits.
The fire resistance limit according to W is characterized by achieving the maximum value of heat flux density at a standardized distance from the unheated surface of the building structure (see. Technical regulations on fire safety requirements No. 123-FZ).
The fire hazard of building materials is assessed as follows: fire technical characteristics: combustibility, flammability, flame spread over the surface, smoke-generating ability and toxicity. For example, in terms of flammability Construction Materials are divided into:
G1-low flammable;
G2-moderately flammable;
G3-normally flammable;
G4-highly flammable.
Construction materials are similarly divided into other fire hazard characteristics (see SNiP 21-01-97* “Fire hazard of buildings and structures”).
Table 3
| Room categories | Characteristics of substances and materials located in the room |
| A. Explosion and fire hazard | Combustible gases, flammable liquids with a flash point of no more than 28°C in such quantities that they can form vapor-gas mixtures, upon ignition of which an excess explosion pressure in the room exceeds 5 kPa. Substances and materials capable of exploding and burning when interacting with water, air oxygen or with each other in such quantities that the excess design explosion pressure in the room exceeds 5 kPa (0.05 kgf/cm2) |
| B. Explosion and fire hazard | Combustible dusts and fibers, flammable liquids with a flash point of more than 28°C. Flammable liquids in such quantities that they can form explosive dust-air or steam-air mixtures, the ignition of which develops an excess explosion pressure in the room exceeding 5 kPa (0.05 kgf/cm2) |
| B1-B4. Fire hazardous | Flammable and low-flammable liquids, solid flammable and low-flammable substances and materials (including dust and fibers), substances and materials that can only burn when interacting with water, air oxygen or with each other, provided that the rooms in which they are present in stock or in circulation, do not belong to categories A and B |
| G. | Non-flammable substances and materials in a hot state, the processing of which is accompanied by the release of radiant heat, sparks and flames. Flammable gases, liquids and solids that are burned or disposed of as fuel. |
| D. | Non-flammable substances and materials in a cold state. |
Table 4
Table 5
| Fire resistance level of the building | Structural fire hazard class of the building | Greatest permissible height buildings, m | Allowable floor area, fire compartment, m2 |
| I | CO CO Cl | 75 50 28 | 2500 2500 2200 |
| II | CO CO Cl | 28 28 15 | 1800 1800 1800 |
| III | CO Cl C2 | 5 5 2 | 100 800 1200 |
| IV | Not standardized | 5 | 500 |
| V | Not standardized | 5;3 | 500;800 |
Table6
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Classification of buildings and structures by fire resistance.
In assessing the fire safety qualities of buildings and structures great importance has their fire resistance.
Fire resistance is the ability of building structural elements buildings to perform load-bearing and enclosing functions in fire conditions for a certain time. It is characterized by fire resistance.
The fire resistance limits of facility structures must be such that the structures retain their load-bearing and enclosing functions throughout the entire duration of the evacuation of people or their stay in places of collective protection. In this case, fire resistance limits must be assigned without taking into account the impact of extinguishing agents on the development of a fire.
The fire resistance limit of building structures is determined by the time (hours) from the start of the fire until one of the signs occurs: a) the formation of through cracks in the structure; b) an increase in temperature on the unheated surface of the structure by an average of more than 140 ° C or at any point on this surface by more than 180 ° C compared to the temperature of the structure before testing, or by more than 220 ° C regardless of the temperature of the structure before testing; d) loss of load-bearing capacity of the structure.
The fire resistance limit of individual building structures depends on their dimensions (thickness or cross-section) and physical properties materials. For example, the stone walls of a building are 120 mm thick. have a fire resistance limit of 2.5 hours, and with a thickness of 250 mm the fire resistance limit increases to 5.5 hours.
The degree of fire resistance of a building depends on the degree of flammability and the fire resistance limit of its main building structures. All buildings and structures are divided into five degrees according to fire resistance (Table 32).
Table 32 Classification of buildings and structures by fire resistance.
| Fire resistance degree | Basic building structures | |||||
| load-bearing walls, staircase walls, columns | external walls made of curtain panels and external half-timbered walls | slabs, floorings and others bearing structures interfloor and attic floors | slabs, decking and other load-bearing structures of coverings | internal load-bearing walls (partitions) | fire walls | |
| I | Fireproof (2.5) | Fireproof (0.5) | Fireproof (1.0) | Fireproof (0.5) | Fireproof (0.5) | Fireproof (2.5) |
| II | Fireproof (2.0) | Fireproof (0.25); fire-resistant (0.5) | Fireproof (0.75) | Fireproof (0.25) | Fire-resistant (0.25) | Fireproof (2.5) |
| III | Fireproof (2.0) | Fireproof (0.25); fire-resistant (0.15) | Fire-resistant (0.75) | Combustible | Fire-resistant (0.25) | Fireproof (2.5) |
| IV | Fire-resistant (0.5) | Fire-resistant (0.25) | Fire-resistant (0.25) | » | Fire-resistant (0.25) | Fireproof (2.5) |
| V | Combustible | Combustible | Combustible | » | Combustible | Fireproof (2.5) |
Note. The fire resistance limits (h) are indicated in parentheses.
This division into degrees was introduced by SNiP II-A. 5-70, which gives nine notes to keep in mind when using the table.