What is the fire resistance limit of building structures?
The fire resistance limit of a structure (according to Federal Law 123 (Russian building code) is the period of time from the start of fire exposure under standard tests to the onset of one of the limiting states normalized for a given construction.
Limit states are indicated by the following abbreviations:
R is the loss of bearing capacity;
E – loss of integrity;
I – loss of heat-insulating ability due to temperature increase on the unheated surface of the structure to limit values;
W – reaching the limit value of the heat flux density at a standardized distance from the unheated surface of the structure.
S – smoke and gas tightness (for filling openings in fire barriers)
The classification of building structures of buildings and structures depending on their ability to resist the effects of fire and the spread of its dangerous factors in accordance with the Federal Law “Technical Regulation on Fire Safety Requirements” Federal Law 123 dated July 22, 2008 as amended on July 29, 2017 (Russian building code).
1) non-normative;
2) at least 15 minutes;
3) not less than 30 minutes;
4) at least 45 minutes;
5) not less than 60 minutes;
6) not less than 90 minutes;
7) at least 120 minutes;
8) at least 150 minutes;
9) at least 180 minutes;
10) at least 240 minutes;
11) at least 360 minutes.
For example, EI 60 means a fire resistance limit of 60 minutes in terms of loss of integrity and heat-insulating ability, regardless of which of these limiting states of the structure occurs earlier.
EI 30 means a fire resistance of 30 minutes in terms of loss of integrity and heat-insulating ability, regardless of which of these limiting conditions of the structure occurs earlier.
R 60 means the limit of fire resistance in bearing capacity is 60 min
R 30 means the limit of fire resistance in bearing capacity is 60 minutes