Fire and other safety features of high rise buildings and structures is essential. Types and concerns related to these features is discussed.
The high-rise building construction concept when compared with other buildings, possess certain features and characteristics that makes them unique and highlighting. The high-rise buildings are considered as the product of the modern evolution. It is filled and composed of sophisticated systems and essential components.
Each of these systems carry out special roles either positive or negative. These elements have an effective role in the overall fire department’s operation.
Most of the components in the high-rise construction focus on safety during emergency or fire risk. They are more focused on fire systems to protect the occupants.
These will hence demand costlier building systems and unique fire safety codes. The fire and safety issues with different features available in the high-rise building is explained hereby.
Over years, the high-rise buildings have garnered significant attention in the fire safety throughout the world. The multiple floors present in the high-rise building makes great number of persons to travel long vertical distances by the stair during an evacuation.
The public regulations, the design of the building, the ownership, code bodies, the regional, local and federal governments are affected by the high-rise building safety.
The high rise buildings are designed to be safe at all undesirable conditions. But when there is a need for a full scale evacuation, it will be necessary to take quick responsibility for their own safety and planned action from the fire fighters.
Construction Concerns in High-Rise Building Construction
When compared with other form of building construction, high rise building construction have a major focus on the building fire and emergency concerns. To understand this, the first major requirement is to study the number of floors of the building under consideration.
The number of floors both above and below the grade have to be evaluated for the same purpose. The firefighting operations is very much dependent on how these levels are identified and labeled in the building.
For example, if there is a floor which is numbered 13; it is found out whether there exist any other levels like the concourse levels or the mezzanines, or it is found that the floor 13 is where the mechanical level is located and have different mechanical levels. Or sometimes the floor has a penthouse level.
An occurrence of a high-rise fire or any other emergency will ask many questions regarding the high-rise building construction features, that are available.
Hence the Incident Commander (IC) have the role to assign different teams to conduct an ongoing reconnaissance. The team consists of group leaders and division supervisors. Most of the fire department consists of a system officer who is positioned inside the fire command center (FCC).
The system Officer is responsible in the monitor of different building systems like the fire alarm panel, the HVAC system, the elevators etc. The system officer is the important source for the incident commander to gather the data and information of the building which are considered very critical.
The quick determination of the age of high rise buildings and the generation which it falls is also identified by the IC. This is very important to know whether the building make use of any lightweight components, for example, any truss assemblies.
This idea will give us an estimate on how long the fire fighters can operate inside the buildings with reasonable safety.
Concerns on the Structural System the Building Possess
The concerns or question that comes to mind during a fire operation is whether:
- The building is core type or not
- If not Core type, what structural system do the building possess
- If it’s a core type, is the core center or some other type
- Does the building possess a central HVAC system?
This information will help in bringing a quality pre-fire plan. When you consider the use of high rise construction in the world, almost all countries possess high rise building to an appreciable range.
The lack of proper resources and the time constraints will affect in bringing a quality pre-fire plan for the building. But many firms work for developing these pre-fire plan which are very expensive.
It’s a matter of fact that most of the buildings do not possess a plan by themselves nor approach any other company for the same.
Concerns on Static and Dynamic Features of Building
Once the pre-fire plan is considered for a high-rise building, it will stay active until the features of the building remain static. This is hence the main issue because most of the high-rise buildings are dynamic.
With demand, more and more up gradation is brought to the buildings. Any change on features of the building system will affect the plan and the considerations. Hence these plans must be updated accordingly.
Concerns on the materials used in High Rise Building
In the case of a core type structural building, emphasis is on finding out what material forms the structural components, the core, the structural frame, the floor components; whether concrete or steel or both.
Most of the modern high-rise building construction consist of floors where the concrete is poured over a metal deck. Regarding this, the questions arise on
- Whether the load of the floor is taken by the structural frame?
- Is there any I - section to support the floors?
- Is there any fire proofing material used to protect the steel components?
Concerns regarding the roof construction of the building: The material type of the roof, the type of equipment on the roof, the load that is carried by these structural components are the concerns regarding the roof construction.
In high rise construction, the question on whether the roof have the capacity to take the load of a helicopter is raised. Other concerns are on the roof obstructions.
The roof with high parapet walls provide additional safety for the firefighters who are operating on the roof also the ones who have be evacuated. Shorter parapet won’t provide no protection in situations where the visibility is lost due to the smoke or during night operations.
Concerns with Fire Detection and The Protection Systems in High- Rise Buildings
It is very essential to determine and identify the fire detection and the protection system that is available in the building to bring the best fire safety plan.
There may be different types of fire detection devices installed in the building. These include the smoke detectors, the heat detectors, manual pull stations, the rate of rise and etc. It is very essential to determine the location of the fire alarm in the building.
If there is any indication from multiple alarms that are in different locations it fixes the probability of actual fire in the building. When multiple locations of alarms are heard it is recommended to check the lowest alarm.
The sprinkler system in the building is identified if installed. The position or the location of the sprinkler system is very essential. It is also essential to determine the type of sprinkler system in the building; whether it is partial sprinkler protection, or full sprinkler protection or no sprinkler protection. A check on the operation of the sprinkler system has to be examined.
Water Supply in High-rise construction
To construct a fire protection system in the high-rise building, it is very essential to have a comprehensive knowledge on the built-in fire protection systems. Water supply is an essential concern with the fire safety measure.
The mode of water supply for fire protection system must be determined. Not only the source but also the water flow. The water supply equipment as a part of fire protection system will include the gravity tanks, fire pumps, the city water mains and other different components.
In a situation where the primary water supply becomes insufficient or it fails to operate, a backup water supply will be served by the fire department connection (FDC) coming under the area and the locality.
Concerns with the Stairs in High-rise building during a Fire Emergency
Early Identification of number of stairs in the building must be considered. Most of the high-rise buildings will possess two stairs well that runs throughout the height of the building. But most probably one among the two will have the access towards the roof.
In modern high-rise buildings, when the fire alarms of specific zones are activated, these primary stairwells are pressurized. In old buildings, under a fire emergency, one of the stairwell will behave like a smoke tower.
Whatever be the type of stair, scissor type or return type, both are found to be critical under a fire emergency. All information regarding, which stair can be easily accessed for evacuation and which is easily occupied by the fire are very valuable during an emergency plan.
Always a pre-plan during the good performance of the building itself it must be categorized that which stair is used for evacuation and which is the attack stair.
Concerns with the Elevators
All high-rise building will possess elevators. Large buildings will have elevators in more number that are arranged in separate banks that serves separate locations.
Elevators can be considered as an essential parameter for the firefighters. They behave as valuable tools in emergency situations. Operational success is attained by accounting the number of elevators and their type, before undergoing the operation.
The HVAC Systems in High Rise buildings
Most of the modern high rise buildings are equipped with well modernized and sophisticated Heating ventilation and the air conditioning system.
Many buildings are equipped with ventilation system to get rid of smoke and to control the air movement because of fire within the building.
The first and the second generation high-rise building make use of horizontal ventilation. Any chance of smoke found, make them to open the windows. This way blocking of smokes was avoided. This strategy is not possible in the present day modern high rise buildings.
The third-generation buildings where more of sealed ones. These were referred to as windowless buildings. This is not because of the absence of the windows in the building, but the fact that they are designed to be opened or easily broken out.
In a third-generation building, a smoke generated will be collected in a remote area of the building. This problem is well solved by the installation of HVAC system. Sometimes the HVAC system can result in very tragic negative problems also.
The problem of ventilation in high rise buildings is a great issue. Mostly the issue is with the smoke than with the fire problems. The smoke has resulted in countless injuries and deaths during most of the fires in the high-rise building.
The issue with the ventilation in high rise buildings must be considered in the initial planning stage of the buildings, to reduce additional expense.
Concerns with the Utilities in The High-Rise Buildings
The daily utilities in the building like the electricity, water, steam and the natural gas have a very important role in the daily operations of a given building. These operations do have an important role during a fire emergency. A control of these operations is a simple matter and are of less effort which can promote large safety.
Generalization of Fire Damage in High Rise Buildings
The fire damage will be categorized under three ways.
- The detrimental effect for the occupant’s life safety
- Structural Damage
- Damage to the properties-Non-structural damage
Among most of the fire incidents that have been recorded, it is observed that the injuries and the loss of life is less. What everyone wish is to bring a less effect on the property damages also.
The migration of heat and the smoke within the high rise buildings is a great threat for the occupants within the building. Most of the death due to fire accidents are caused within the dwellings.
The fire will result in the formation of toxic gases that is very dangerous to the human health. In such situations, the structural damages have least importance when compared with the life safety. After extinguishing the fire, it is found that the structure is subjected to water damage. The repair and the maintenance is a great economic loss.
The high-rise buildings are stuffed with large equipment which are numerous are costly. Fire will bring lots of property loss due to these reasons. These reasons have resulted in the bankrupt of many companies as their production process was completely stopped and lost the market.
There are many factors that affect the fire and safety concerns of a high-rise building. It is always recommended that how extreme be the fire damage, the measures and operations must bring life safety as the primary concern. This will ask for fire and building codes that will possess both passive and active fire protection systems in order to reduce the fire damages.
Performance Based Design for Structural Safety Against Fire
Performance based design concept is the design the buildings according to the main goals. PBD is hence regarded as one of the best solution for this problem of fire issues in structural point of view.
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Fig.1. Different Performance Levels in Performance Based Design
The selection of a level from the levels, Immediate Occupancy (IO), Life Safety (LS), Collapse Prevention (CP) is the basis on which the building design. This is mainly a design concept used in earthquake resistant structures.
Each level has different damage states. In fire-resistant design, the life safety level is used, where we expected to have damages to the building with no harm to the life. It can be sometimes chosen between IO and LS also.
The PBD design will provide more on the provision of hinges in more critical point of the structure making the building more ductile. This ability to provide the performance hinges will describe the ability to have fire dynamics in the spaces of the tall buildings.
How severe be the fire, the structure should stand still letting all the life to be safe, this must be the output of a PBD design.
Understanding and studying the fire accidents happened in a modern building will help to assess the critical components that are involved in the fire safety strategy. As this truly reflects the nature of the tall buildings.
[ Ref: Cowlard[2013], Fire Safety design for tall buildings, Science Direct].