How to distinguish the fire resistant level of construction materials?
There are 3 conditions for building components to reach fire endurance, namely: Loss of ability to support; loss of integrity; loss of fire insulation function. As long as one condition occurs, fire endurance is reached and the time before it is called fire endurance. 1), loss of ability to support: If the specimen bearing capacity and rigidity reduce, section area shrink, collapses or deformation exceeds specified numerical value because it cannot bear the load of original design under flame or high temperature, it loses the ability to support. 2), loss of integrity: It mainly refers to the thin wall separating component(such as stairs, windows,partitions, ceiling, etc.) burst or partially collapse under flame or high temperature, and penetrating?fracture or opening appears, and the reverse side even burn. For example, when the floor is under flame or at high temperature, the flame spread to the upper room, which indicates that the integrity has been damaged. 3), loss of fire insulation function: It mainly refers to that seperating components loses thermal insulation and excessive heat conduction. In experiment, if the average temperature of component unexposed surface exceeds 140 ℃, or if any spot at the unexposed surface exceed the initial temperature of 180 ℃, the component loses fire insulation function.
Division of fire resistant level of building material: 1, It can be divided into five levels according to the importance: a, special class: commerative, historic, international and national buildings. b, Class A: high-grade residential architecture and public building. c, class B: middle-grade residential architecture and public building. d, class C: orinary residential architecture and public building. 2, It can be divided into four grades according to fireproof?performance: Fire resistance level buildings is divided into four levels. Standard of fire resistant level is based on the combustion performance and fire endurance of main components of the house. 3, It can be divided into 4 levels according to durable life: a, A grade durable life, over 100 years, for important buildings and high-rise buildings. b, second level durable life, from 50 to 100 years, for ordinary buildings. c, third level durable life, from 25 to 50 years, for secondary buildings. D, fourth level durable life, less than15 years , for temporary buildings. I hope my answers will help you.
Building materials fire resistant level is divided into four levels, among which the first level is the highest, with strongest fire resistance; fourth level is the lowest with weakest fire resistance. Fire resistance level of buildings depends on combustion performance and fire endurance of the building components. The building components refer to a series of basic components such as the building walls, foundations, beams, columns, floors, stairs, ceiling, etc.
