Fire protection system and the associated fire protection strategies are of key importance to any building. Safety is an integral part of the modern world building designs and the Engineers/designers around the word have developed key procedures that can help in modeling active fire protection systems.
This review highlights the importance of fire safety strategies and the tools that may be used for fire protection in buildings such as stores, cinemas etc. A brief discussion regarding the most suited protections systems, design and safety policies will be followed by evacuation procedures in high rise public buildings.
The prevention of fire is of more importance than fire fighting & must be the first consideration of entire community. Most fire outbreaks are caused by irregularities or carelessness. Tidiness & cleanliness are basis of good fire precaution. Before the fire protection systems are designed and installed, it is important to review the possibilities of fire breakout and its causes for specific building occupants. In this case study, the possible causes of fire out break are analyzed for large public buildings such as IKEA type stores.
Analyzing the residential behavior of the building occupants can highlight many aspects of the possible fire hazard. For large commercial buildings such as IKEA, many fire outbreaks are normally caused by;
These analyses are considered to be very important as the ‘final design of the safety strategies and tools for fire protections’ heavily depends on its outcomes.
Once the possible fire outbreaks analyses are completed, fire precautionary measures are considered so that the designers can estimate the risk factors and produce numerical models of fire appropriately. For example, storage of highly flammable liquors can be banned inside the building so that it assumed that no explosive materials will be present inside the building in the event of fire break out. The following precautionary will be implemented in this case study.
The following important factors and the behavior of fire in the effected building are considered in the design of the fire protection system
Where, Q is the rate of energy release/surface are (fuel), q is heat flux, Lv is the latent heat of vaporization, Hc is the heat of combustion (ASCE, 1999)
The fire can spread through the radiation process of the burning object or through the object to object heat transfer. The fire can be ventilation controlled if the rate of the burning (based on the type of fuel and heat-flux) exceeds the available air supply in the affected area. Given the constant value of the release of heat per-unit of oxygen (assumed for normal fuels), the required air volume needed to support the fire can be determined.
The ability of property to resist or withstand fire is called the fire resistance. This ability can enhance fire protection in many cases in the building. Therefore different fire ratings are required for specific buildings that are specified as building codes. These codes represent the fire resistance design based on the covered area, building-occupancy and the building load. These codes are based on the experimental results; however, the actual severity of the fire can be only determined by the many other additional factors which are note currently included in the building codes.
Recent work by researchers on fire safety using analytical methods has been quite successful and it is becoming more and more popular in engineering and safety designs of the building codes. The numerical methodology to calculate the building or structural fire resistance has also made progressive development. Numerical methods are reliable and quite cost effective and these may be applied/used in specific situation analyses (Mike, 1999)
A calculation method has been described in euro codes which can be perform calculations on the steel that is exposed to actual-fire. The following are the analyses that should be conducted for the numerical modeling of fire resistance (ASCE, 1999)
Mechanical as well as thermal properties of the material are of key importance of structural member’s performance in the building. For steel, the strength and the deformation resistance decrease as the temperature increase. Same is the case with concrete; however the change in these properties can vary depending on the thickness and the quality of the material used. There are minimum requirements that need to be met; in the building structure that defines the minimum strength of the materials to be used. Trusses and beams perform differently depending on the conditions and the methods of fabrication
The structural-mechanics analyses can analyze the performance of the structural members that are exposed to the fire. The steels used in the design of the buildings are normally hot rolled or cold drawn. The strength of such steel depends on the carbon-content.
The most important aspect of the life safety strategy is the ‘high rise evacuation process’ in the buildings as it can save the life of the occupants and the emergency safety team. The safety of life can be provided to the building occupants either by providing safe evacuation procedure or by providing in-place fire protection (SFPE, 2000)
Considerable number of safety exits should be provided with appropriate widths for safe evacuation. The building occupants must be provided an easy access to multiple exits so that the exits could be easily found and that not all of the exits are blocked in case of an emergency. The exit route must be constructed as fire rated protected. This rout may also be smoke protected to provide smoke free exit to the occupants.
The access path to the exit route and the subsequent exit is designed such that the occupants can find this path along the offices or shops. The stair ways in the high rise buildings can also provide the exit path. Many safety codes require that the exit path leads the occupants directly outside to a safe place, however codes such as (NFPA 101) allow maximum of half of the exit to discharge inside the building if some provisionary conditions are met.
Total evacuation plan is implemented during the fire emergency as it signifies the safe evacuation of all the residents of the building. Phased evacuation is however used for multiplex buildings, residential buildings and high rise office and malls. At the movement activation point, the residents in the first affected areas are evacuated first, than the other residents are evacuated. It’s a schematic process that helps to avoid creating panic.
Simultaneous evacuation involves in managing the psychological and physical responses of the people
Usually used for evacuation of malls and cinemas.
The following active safety fire protection systems/tools and equipment are used for such buildings;
This complete fire protection system is very elaborate but it can be very expensive, however there are minimum requirements that a system should follow such as placement of the fire fighting equipments, safe building design, placement of clear safety signs etc.
The fire strategy is designed to fulfill and achieve the objectives of the various hearth building laws. The multi-use building features a shopping center occupying one floor. There should be at least 2 fire escapes in the building. Entrance to the fireplace escapes should be protected by locked doors that are preferably fire resistant (NFPA 101).
Distance for travel to the hearth exits is calculated based mostly on the occupant load and also the expected time for evacuation. The exit widths are designed to be large enough to evacuate this load of occupants. Clearly identifiable and readable signs are placed to indicate the location of exit doors. Fire fighting equipments are put in like portable fire extinguishers, Sprinklers, hearth doors etc. Built in architecture and revised architecture are compared. The structure is designed to resist intense fires and have a few hours fire resistance rating. It is expected that people should move towards safe location before the fire is quenched.
Fire trucks should have easy and clear access to the central building in fire cases. As shown in fig below, sufficient space for a fire truck to adopt a hardstand position from where the fire can be doused is shown. Building and floor occupant load factors are used to calculate the number of people who should be allowed to occupy one square meter of space. It is decided by the fire fighting agencies and as per international laws and rules.
In case of a Fire Emergency, the Security team must be notified immediately. Security department has the training and responsibility for managing fire emergencies and summoning outside assistance when necessary. During a fire emergency, only authorized individuals may remain in the building to fulfill their responsibilities. All other occupants must immediately evacuate the building in accordance with the emergency procedures. Unauthorized re-entry into a building during a fire emergency is not permitted (NFPA 101)
Building occupants are not required to fight growing fires. Individuals who have been trained in the proper use of a fire extinguisher and are confident in their ability to cope with the hazards of a fire may use a portable fire extinguisher to fight small fires. Fire fighting efforts must be terminated when it becomes obvious that there is risk of harm from smoke, heat or flames.
Figure-1: Active Fire protection system case study
Each building must designate a safety Incharge who is the first point of contact for questions about the emergency procedures and the emergency action plan. The details of locations of Installed Active Fire Protection Systems such as Fire Extinguishing systems must be in position of the safety Incharge.
Fire Exit Map/route must also displayed along with the necessary information regarding the fire exits. For Small Fires, Portable fire extinguishers suitable to the conditions and hazards involved should be provided and maintained in an effective operating condition. For Large Fires, Fire hydrants should be installed that shall be used for specially trained personnel of fire extinguishing services.
In case of an emergency, emergency evacuation procedures must be followed. After the building occupants have left the building through the nearest stairwell, they should go to the Designated Assembly Point (e.g. back of building). At the assembly point, supervisors will account for personnel and notify the Safety Incharge or security Team if any personnel are missing.
During an emergency, visitors who may not be familiar with this plan must be informed of the requirement to evacuate. Special attention should also be given to any persons with disabilities, especially those who are visitors or unfamiliar with the building.
Additional Duties: Additional duties may be required for assistance during an evacuation or the shut-down of special processes or equipment.
Training: The building manager of the safety Incharge is responsible for training its employees on all elements of its emergency action plan. New employees must receive training when first assigned to the department. Additional training is necessary when an employee's required actions under the plan change, or when there are changes to the plan.
Additional training assistance should be attained when so required through government safety departments
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