Ways of Designing Fire Safety in Structures
Fire is a rapid oxidation process accompanied by the evolution of heat, light, frame and the emission of sound. The three elements required for fire to ravage a structure include fuel, oxygen and heat. The dire effects of fire outbreak on the safety of lives and properties have necessitated designing of buildings with an acceptable fire safety measures in order to minimize the risks that may arise from heat and smoke.
Designing buildings with enough fire safety will limit the potential for injury and death among the occupants of the buildings. Fire safety is an essential design consideration as it provides protecting contents that make the building reparable and continues to function after a fire incident.
Design Strategies for Fire Safety in Buildings
The aims of these fire protection design strategies are:
- to prevent fire;
- to safeguard the lives of occupants; and
- to reduce damage on the building, its contents, and on surrounding buildings.
Classification of Fire Protection Design
There are two main classifications of fire protection designs.
- Passive fire protection; and
- Active fire protection.
Passive Fire Protection
This is the use of building components to control or limit the impact of fire. For instance, building components such as walls, floors, ceilings, etc. can be designed with:
- the ability to maintain loadbearing capacity, thereby resisting collapse;
- ability to maintain their integrity; and
- ability to provide insulation from high temperatures.
Walls and Doors
Fire-rated walls and doors are used to contain fire. For instance, fire-rated walls are intended to prevent horizontal passage of fire. The fire rating of the wall may vary from 20 minutes to 4 hours and may be calculated for a fire exposure on one or both sides of wall. The doors in these walls also have a fire rating, which is usually lower than the fire rating of the wall. This is because the building contents, which serve as the fuel, are not located in front of the door. Hence, the fire exposure to the door can be less than what is experienced by the wall.
- Fire wall/fire partition: a fire-resistance-rated wall that extends continuously from slab to slab, has fire-rated protected openings, and restricts the spread of fire.
- Party wall: A fire wall on an interior lot line used or adapted for joint service between two buildings.
- Smoke barrier: A continuous membrane that resists the movement of smoke.
Floors and Ceilings
There are also fire-resistant rated floor and ceiling, which creates a horizontal barrier to prevent the spread of fire from one floor to the next. It may consist of a concrete or protected steel floor slab, a fire-rated system, or combinations of both. Like fire-rated walls, fire-rated floors and ceilings should have the least number of penetrations possible. If penetrations occur, they must be constructed to the same rating as the floor or ceiling they pass through. Codes usually contain special provisions to permit large openings from one floor to the next.
For one-storey or two-storey buildings, windows and doors provide adequate escape routes in the event of a fire. But, in case of multi-storey buildings, the location of the staircase is essential. It should be equally accessible from different points of the building. As far as the material is concerned, it is advisable to use R.C.C. for building stairs. Also, enclosure walls made up of fire-resistant materials should be built around the staircase hall for further safety.
There can be two types of framed structures, reinforced concrete and steel structures. Steel structures generally tend to twist and distort under heavy fire. Therefore, they are given a protective coating of metal lath or plaster. Bricks, concrete, or tiles may also be used, and their minimum thickness should be 10 cm.
Flat roofs are known to be desirable when considering fire safety, as fire spreads more rapidly on a sloped surface in case of unfavorable wind conditions. But in the case where the design and its peculiarities require a sloped roof, you may consider building the ceilings or coating it with fire-resistant.
Active fire protection measures are those that take direct physical action to reduce the growth rate of fire or the migration of smoke. These measures are often activated either automatically or manually. They include sprinklers, fire hydrants, extinguishers and smoke detectors. In the event of a fire, they will be activated by some agent or form of communication, informing people or equipment of the presence of fire and instructing them to take measures to contain its spread.