A High Rise Primer

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A High-Rise Primer

Scope What are High-Rises High-Rise Construction

What are High-Rises

High-Rise ConstructionEven though variations can occur, most cities consider a high-rise building as one thatis over 75 feet in height measured from ground level access to the floor level of thehighest floor intended for occupant use, not the actual height of the building. Based onan overall review of construction methods for high-rise buildings, buildings in certainparts of the United States are engineered differently. For example, buildings located inCalifornia are engineered for seismic conditions which are common to that area whilethe high-rise buildings in the New York region are built to withstand the wind impact onthe higher buildings. Based upon the following information obtained from the Los

Angeles Fire Department, there are approximately 1,700 high-rise buildings in the Stateof California, and approximately 745 of these are in Los Angeles. The majority of thehigh-rise buildings in Los Angeles are commercial occupancies. About 20 to 25 percentare habitable, such as hotels, apartment buildings, and condominiums.The Los Angeles Fire Department divides its high-rise buildings into two groups:"Existing High Rise" and "New High Rise." The exact building features and functionalsystems that are found in a particular high-rise building will generally be determined bythe age of the building and the various code requirements that were in effect at the timeof construction. Because all high-rise buildings are not the same and because familiaritywith construction features and functional building systems are so vitally important to thedecisions and actions that are taken during high-rise fire control operations, the need for

effective pre-incident planning cannot be over emphasized. Existing high-rise buildingsinclude those that were constructed prior to July 1974. Approximately 520 of thehigh-rise buildings in Los Angeles fall into this category. For convenience, existinghigh-rise buildings may be separated into two subgroups: those constructed prior to1960 and those constructed between 1960 and 1974. A new high-rise building is onethat was constructed after July 1974. Approximately 225 of the high-rise buildings in Los

Angeles are new high rises.

History of Existing High-rise Construction, 1900 to 1960Prior to 1957, all buildings in Los Angeles were limited to 150 feet in height as ameasure of earthquake safety. Several years passed after the repeal of this limitation

before taller buildings were constructed. Therefore, most p1.e-1960 high-rise buildingsare a maximum of 13 stories. The pre-1960 high rises were generally constructed with areinforced concrete exterior as opposed to steel "I" beam construction used today. Manyof these structures are located in the older downtown area of the city.

History of Existing High-rise Construction in Los Angeles, Post 1960

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By the end of 1957, the city adopted more stringent earthquake standards. The150-foot restriction was repealed, and building codes lifted the restrictions limiting theheight of Type I buildings. Like the earlier existing high-rise buildings, the post-1960group are also Type I (fire-resistive) construction. By the 1960s, the Los Angeles codesrequired compartmentalization of structures. Compartmentalization subdivides the

buildings into "fire areas." These separations were designed to establish a"compartment" to prevent fire extension and provide for life safety. Fire doors and otherfire protection assemblies are installed to protect penetrations through these separationsin order to control the spread of smoke and fire. All high-rise buildings constructed inthis era are Type I, fire-resistive construction throughout. Type I construction usesstructural members, walls, columns, beams, floors, and roofs that are noncombustible orlimit the amount of combustible materials. Type I buildings are designed to withstandthe most severe fire conditions to be expected within the building. These structures arerequired to have a two-hour fire protection rating on girders and beams. The floors, stairshaft, and elevator hoist-ways are also protected for two hours. However, instead ofusing reinforced concrete, they were generally built with steel beams coated with a fire

retardant material. The floors and roof are constructed of concrete slab or steel deckingcovered with concrete. The only combustible materials allowed are the interior partitionwalls and office furnishings. Most high-rise buildings of this era are of the "central core"design type. This style features elevators and stair shafts located in the center of thebuilding, surrounded by a corridor and outer tenant areas.

History of Existing High-rise Construction Post 1974The construction methods and ratings are the same as post 1960 but have added theadditional use of life safety features.

The World Trade Center

The World Trade Center complex consisted of seven buildings on a 16- acre site. The110-story twin towers, One (North Tower) and Two (South Tower), stood at the heart ofthe complex to a height of 1,368 feet and 1,362 feet, respectively. At the time of theircompletion in 1973, the World Trade Center Towers were the two tallest buildings in theworld. Each tower had approximately 40,000 square feet, or one acre, of office spaceper floor.

Faced with the difficulties of building the World Trade Center Tower to theseunprecedented heights, a unique architectural design was employed. A hollow tube ofclosely spaced perimeter columns formed the main structural component of each tower.Each tower was supported primarily by a series of 61 rigid, closely spaced steel columnsbuilt into the exteriors on each side. Lightweight, steel trusses extended across to acentral core. These exterior pillars supported their own weight and half the weight of thefloors. The perimeter columns supported the floor trusses. The structural integrity of theWorld Trade Center depended on the closely spaced columns around the perimeter.

A cluster of columns at the center of the structure supported half the weight of the floors,their own weight, and all the elevators and other mechanical systems. Steel trusses tied



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the two sets of columns together, providing reinforcement. The central core of thestructure was not part of the main structural system of the building due to the enormousload they bore in supporting the elevator system (each tower had 104 passengerelevators).

The World Trade Center Towers were designed to withstand the impact of a Boeing 707airliner. Speculation to the cause of the World Trade Center Tower collapses at the timeof this publication was most likely due to a combination of the impact from thecommercial airliner(s) and the subsequent fire accelerated by thousands of gallons of

jet fuel. Whether failure was initiated at the perimeter columns or the core is unknown atthis time. It is likely that the impact of the airliners destroyed a significant number ofperimeter columns on several floors of the building, severely weakening the entiresystem. The subsequent fires, fueled by up to 20,000 gallons of aviation fuel, createdenormously high and prolonged temperatures affecting the structural integrity of thebuilding's structural components, subsequently weakening the infrastructure of thebuilding leading to the collapse of the structure. Additionally, the location of impact may

have resulted in the South Tower imploding before the North Tower. The South Towercollapsed 56 minutes after the impact, and the North Tower collapsed 1 hour and 40minutes after it was struck by the airliner

High-rise Fire ConsiderationsIn the history of modern high-rise fires, there have been few documented incidents ofbuilding collapses as a result of fire alone. The Incident Commander at a high-riseincident is faced with more complex operational priorities than those in a smallerstructure. These operational priorities and considerations include life safety (personneland occupants), extinguishment, fire confinement, property conservation, personnelaccountability, and evacuation. At a high-rise fire, time is a critical element. As fire

department resources arrive on scene, the strategy developed based on the situationwill dictate the operational priorities and the overall success of emergency operations.

High-rise structures are designed to withstand "content" fires for a specific length oftime. Building design features (such as fire retardant materials) and building safetyfeatures (such as sprinkler systems) help to contain fires or extinguish fires and preventthe building infrastructure from being exposed to excessively high temperatures. Basedon these factors, fire departments should continue to implement standard operatingprocedures for high-rise fires. Implement the following guidelines at high-rise fires:1. Use an aggressive attack on the fire because it is the most effective means of

saving lives and facilitating rescue in a high-rise fire emergency.2. Evaluate the location of a Command Post. Some fire departments set a minimum

of 200 feet from the structure.3. Locate Base a minimum of 200 feet from the structure and not in proximity to the

Command Post. Consideration for the location of Base should relate to a safecorridor for personnel approaching and entering the building.

4. Evaluate and continuously reevaluate the overall strategy through-out theduration of the incident. Conditions will definitely change, and these changes will



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impact strategic planning.5. Consider the pressurization of all stairwells to ensure tenability for fire fighting

operations as well as evacuation.6. Gaining control of stairwells in a spontaneous evacuation situation may require a

considerable amount of time and personnel.

7. Unless fire attack teams gain control, the fire location may be negativelyimpacted.8. Follow current department elevator policy in using only elevators that terminate

five floors below the incident area. This may provide an alternative access if firedepartment personnel can ascertain that the elevator lobbies and shafts are notthreatened by fire.

9. Gaining control of an evacuation and providing information and direction tobuilding occupants will be greatly simplified in modern buildings that are equippedwith a public address system.

An Incident Commander faced with an incident similar to the World Trade Center Tower

fires must use the following guidelines:10. Make an analysis of the potential collapse zone, identify a safety zone, and focuson an immediate evacuation.

11. Consider requesting and using a technical specialist, such as the buildingengineer or a Department of Building and Safety structural engineer, to assist theIncident Commander and/or Planning

12. Section Chief in evaluating ongoing strategy and determining the overall safety ofcontinuing fire suppression operations.

13. Be prepared for the possibility of complete self-evacuation of a high-rise building.If mass evacuation is occurring, resources should be assigned to coordinate andestablish safe corridors to a refuge area that will result in a minimal impact onincident operations.

14. Use the building communications system located in the fire control room to advisethe building occupants to evacuate the building.

15. Locate Base and the Command Post at least 1,000 feet away from the building.16. Ensure that stairwells with roof access can be opened without any special tool or

key.17. Require building owners to provide a helispot and to keep the roof clear of any

obstructions.18. Implement a plan for requesting helicopters to provide rooftop rescues.19. Review department standard operating procedures and conduct building

familiarization training.

High-Rise Construction Considerations

High-rise DefinitionHigh-Rise is a term that can be used in code definitions, for example: any building over75 feet (23m) or 5 stories in height is considered a high-rise building. However, any tallbuilding that has characteristics and limited access or external characteristics of a"classic" high rise



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In some older cities high-rise buildings exist that have unreinforced masonry wallconstruction. These buildings are prone to destruction in fires as well as a potential tocollapse in earthquakes.

"New-style" High-rise Construction

The modern method of constructing high-rise buildings is commonly called "coreconstruction." This method involves erecting a steel skeleton by using a column, girder,and beam system. The elevators, stair shafts, utility shafts, etc., are placed in a corearea. Most commonly this core is found in the center of the building and is called"center- core" construction. It should be noted that in some buildings this core will befound on the side and called "side-core" construction. In these cases, the stairways andelevators are located on exterior walls.

Core construction has less mass than "old-style" construction and is more vulnerable toheat from a fire. Floors have been known to sag nearly two feet under intense fireconditions and, in at least one case, several portions of the wall assembly fell from the

building. Codes have generated requirements to have fire resistive coatings sprayed onsteel support members that assists in maintaining the strength of the steel when it issubjected to heat and/or flames.

Structural Framing SystemsThe structural frame of a high-rise building is the skeleton of the structure that supportsnot only the dead load of the building itself, but it also supports the live loads such asoccupants and building contents. The most common systems in high-rise buildings useeither of the following as the basis for forming the building skeleton:27. Reinforced concrete (old-style)28. Structural steel (new-style)

Both types use vertical interior and exterior columns to which lateral girders areattached. The girders span the horizontal distance between the columns and supportstructural beams. Although there is a difference in the materials used for the structuralelements in a concrete versus a steel structural frame, they serve the same function.

The construction design for high-rise buildings is based on the concept that thestructural integrity of the building must be maintained sufficiently in any potential fire.Principal structural components have a high degree of resistiveness from heat.However, there are a number of structural stability concerns during fire conditions withwhich fire personnel must be concerned:29. Component failure is possible under prolonged exposure to sufficient heat.30. Failure of a floor beam is somewhat serious, but it is also localized.31. Failure of any girder would be far more critical than a floor beam because it would

affect a significantly larger area.32. The failure of one or two girders could cause instability of a column, potentially

leading to a progressive collapse of the framing system.33. A column failure could result in serious structural instability. Depending on the

location of the column, it could conceivably trigger extensive collapse damage to



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the structure.

To achieve the fire protection required by building codes for Type I (fire-resistive)construction, steel frame members in high-rise buildings are "fireproofed" by encasingthem in concrete, sheet rock, or by spraying them with a protective coating. Concrete

has the advantage of being the most permanent type of fireproofing, but its use is limiteddue to the effect that it has on the dead weight of a building. Sprayed-on protectivecoatings improperly applied can spall during a fire. This may leave the steel structuralmember exposed and subject to failure from excessive heat.

Concrete frame structures tend to resist the effects of fire better than steel framestructures, but they are less resistant to the effects of earthquakes. The ability ofproperly designed and constructed steel frame high-rise buildings to withstand moderateearthquakes has been proven in many parts of the world in recent years.

Exterior Walls

As stated above, the exterior walls of an "old-style" high rise are part of the bearingmembers. The wall construction is reinforced concrete. These walls are very thick atthe bottom and become smaller as they rise.

The exterior walls of modern high-rise buildings are commonly prefabricated and aretypically lighter in weight than those in older buildings. In many cases, these walls arenon-load bearing and may be referred to as "curtain" walls. A complete curtain wallconsists of a panel with finished surfaces and a means for attaching it to the buildingframe.

The most common method for attaching curtain walls to the building is by bolting them to

clips that are attached to the structural frame or floor slab. This method of attachingwalls often leaves a space of several inches between the end of the floor and theexterior wall. Unless this space is sealed with an effective fire and smoke barrier, it canprovide a path for fire and smoke spread to floors above and allow water to penetratefloors below.

The outside finish of a modern high-rise building is often referred to as the "skin" andusually consists of decorative materials such as aluminum, stainless steel, or lightweightconcrete, with large window areas. These windows may be plain glass, tempered glass,or decorative glass. Metal alloy frames, backed up with conventional construction, holdthe glass in place.

WindowsVentilation complexities will usually be dependent on the type of windows installed in thebuilding. Inoperable windows complicate ventilation procedures. Operable windows,used in conjunction with normal smoke removal equipment, simplifies ventilation.

High-rise residential buildings normally have operable windows made from regular plate



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glass. In addition, many high-rise apartment buildings have large sliding glass doors thatopen onto balcony areas. Windows in high-rise office buildings are often inoperable.They are typically plate glass. When broken, plate glass often produces large shardsthat can cause serious injuries to those below. To reduce this risk, special "tempered"glass windows may be required at certain locations for emergency ventilation. When a

tempered glass window is broken, it will shatter into very small pieces, providing adegree of safety that is not offered by plate glass under the same circumstances.Depending on applicable building codes in sealed buildings, tempered glass or operablewindows on every floor may be required. Usually, they are located in each corner of theexterior wall and at specific horizontal intervals. These special windows are normallyrequired to be aligned vertically throughout the building. Tempered glass windows arenormally marked as such in one of the lower corners. A decal may be affixed in a visibleplace near the window.

Instead of tempered glass for emergency ventilation, some buildings may be equippedwith special operable window panels that are secured from the inside by a tool-operated

locking device. This tool is required to be kept on the premises.

NOTE: Removal of window glass during a fire situation, whether caused by the fire ordone intentionally for ventilation purposes, can create a situation where fire can extendup the building exterior to the floors above. Anytime glass is removed or fails,consideration must be given to the possibility of exterior lapping.

RoofsRoofs on high-rise buildings are required to have at least a two-hour fire-resistive rating.In most cases, concrete construction exceeds this requirement. Careful considerationmust be given to roof configuration during pre-incident planning. Pay particular attention

to:34. Stair shaft exits35. Machinery rooms36. Other obstructions that would limit certain types of ventilation activities on the roof

In many cases, all stair shafts in the building will not exit to the roof. Knowing whichstair shafts exit to the roof can be critical when moving occupants to the roof for saferefuge or evacuation and when using stair shafts to exhaust smoke. It is also importantto know if it is possible to land a helicopter on the roof for a top-down approach to firefighting, for interior rescue, or to lift building occupants from the roof.

In most cases, unless the code under which the building was built required the provisionof a helipad, it will probably be impossible to land a helicopter on the roof. Variousobstructions such as machinery rooms, antennas, or lack of adequate landing space willusually be found.

Shaft Enclosures



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Shaft enclosures in high-rise buildings are required to have a minimum of a two-hourfire-resistive rating. Examples of shaft enclosures are stair shafts and elevator shafts.

Any vertical shaft in a high-rise building, under fire conditions, can transfer heat andsmoke to other parts of the structure. It is critical that shaft integrity be maintained.These shafts may be used as an escape route for building occupants or as an access

route for firefighters. Failure to maintain the integrity of vertical shafts can:37. Transfer products of combustion to remote parts of the building38. Impede the safe exit of building occupants39. Greatly restrict the ability of fire personnel to perform tactical operations

Shaft SystemsHigh-rise building stair shafts are often built into the center core. Additional stair shaftsmay be on the structure's outer perimeter or elsewhere, depending on the height andoccupancy type of the building.

Besides conventional stair shafts, there are other special stair shaft types found in

high-rise buildings. The building may contain "pressurized" or "smoke-proof' stair shaftsin which a vestibule design or activation of special equipment is designed to provide asmoke-free atmosphere within the stair shaft. In many cases, however, even though thebuilding has multiple stair shafts, only one stair shaft may be designed to provide thissmoke-free environment.

Some high-rise buildings feature stair shafts that are often referred to as "smoketowers." These are either full?. or partially open to the outside atmosphere to preventsmoke from filling the stair shaft. Some high-rise buildings have "scissor" stair shaftsthat feature two sets of stairs in one column on shaft. In some cases, each set of stairsmay serve every floor, I~ut entry points at alternate floors are on different sides of the

center core. Some others are designed so that one set of stairs serves only the oddnumbered floors while the other serves only the even numbered floors. While thesesubtle differences may not seem important, under fire conditions they can beresponsible for firefighters approaching the fire from a less than desirable location or canresult in fire personnel going to the wrong floor.

Doors that provide access to the stair shaft from individual floors are often locked fromthe stair shaft side. This requires that fire fighting personnel have a key to provideimmediate access to the floors from the stair shaft. Lacking a key, much time can bewasted in forcing entry to the floor. Forcing the door is often difficult due to the metalconstruction of the door and jamb. It may be faster to poke a hole through the wall andreach inside to open the door.

As a rule, stair shaft systems in high-rise buildings are not designed to handle the totaloccupant load of the building simultaneously. This is further complicated by the fact thatthe number of usable stair shafts may be reduced by heat, smoke, or fire departmentoperations. This is one of the main reasons why total evacuation of building occupantsduring a high-rise fire is often impractical.



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Stair shafts in high-rise buildings should be marked at each landing with signs thatprovide specific information about the stair shaft. The signs should identify the stair shaftby name or number (for example: Stair #1, Stair #2, etc.). They should designate eachfloor, and list the lower aild upper terminal points of that stair shaft (for example: B-3 to18). The sign should also indicate whether the stair shaft provides access to the roof of

the building. This can be critical to occupants who are using the stair shaft under fireconditions, and it can provide critical information to firefighters.FloorsFloors in high-rise buildings are also required to have a minimum of a two-hourfire-resistive rating. Floors are normally concrete poured ver a metal deck that remainsin place after the concrete has set. After he concrete has set, holes are bored in theconcrete to allow for the passage of various utility lines or equipment between the floors.This procedure is called "poke-through" construction. Poke-through, if not properlysealed around the bored holes, can seriously diminish the floor's two-hour fireresistiveness.

While most recent codes require that poke-through openings be sealed with a materialthat reestablishes the two-hour fire resistiveness in many cases, it is not done properlyor is completely overlooked. In older buildings, poke-through may not be sealed becauseof the lack of code requirements when the building was built. The lack of sealing ofpoke-through spaces can allow fire and smoke to travel to upper floors and provide apath for water to travel to floors below. During a fire situation, a check must be made ofthe floors above and below the fire floor to check for extension.

Floor ConfigurationThere are two general floor layouts in high-rise buildings. They are referred to as"compartmentatized" and "open space." The compartmentation in high-rise buildings

is based on the concept that smaller areas are separated from other areas and can slowdown the spread of the fire. This can reduce the fire from spreading beyond theseparated area. An example of this cornpartmentation would be a typical high-riseapartment building.

Compartmentation can be an essential design consideration in limiting the size of ahigh-rise fire. Compartment separations must offer adequate fire resistivity and mustdivide plenum areas above dropped ceilings. They must also prevent vertical fire travelby protective construction features around vertical shafts and above windows. Propercompartmentation also requires all "poke-through" openings between floors to beproperly fire-stopped.

Examples of the "open space" concept are high-rise office buildings where floors arevirtually wide open. This openness is designed to allow unrestricted movement ofemployees throughout the floor. In a fire situation, however, the lack of physical barrierswill allow the fire to spread quickly throughout the floor. Open high-rise floors are dividedby partitions that extend from the floor to the dropped ceiling. These conditions do notrepresent true compartmentation. Should the fire reach the open plenum area above the



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dropped ceiling. it can move unrestricted through the plenum and extend into otherareas of the floor.

Ceiling AssembliesCeiling assemblies in high-rise buildings are usually suspended from the floor assembly

by steel wires attached to a grid of metal channels. These channels hold acoustical tilesor other ceiling material and, in most cases, the lighting fixtures. The open spacebetween the suspended ceiling and the floor above is normally used for horizontaldistribution of utility services (air-conditioning ducts, electrical conduits, plumbing lines,etc.). It often serves as a common exhaust plenum for the heating, ventilation, andair-conditioning system (WAC).

Electrical SystemsElectrical systems in high-rise buildings can be extremely complex and very hazardousunder fire conditions. The amount of electrical power required for the normal high-risebuilding operations, which includes the complex equipment used to distribute it, must be

considered when fires occur.

Much of the electrical equipment is likely to be located in the basement of the building.This makes it susceptible to flooding from broken pipes or water used to control a fire.The danger of working near electrical equipment when water is present is well knownand must be remembered. Sending fire personnel into electrical vaults to terminatepower to the building is usually not warranted for sel era1 reasons:40. The shutdown procedure is usually complicated and requires specific

knowledge on how to perform it safely.41. Randomly throwing switches in these types of situations can be extremely

dangerous. This may terminate power to equipment that should continue to

operate.42. If power must be terminated on the floor or floors involved in the fire, it canusually be done through sub-panels that control the electrical supply to specificfloors. Because of the high voltages and power in electrical vaults, a suddenshutdown by unknowing personnel can cause an electrical

43. surge that can injure personnel doing the shutdown. Have a utility company or thebuilding engineer do the shutdown in electrical vaults.

An emergency power supply, usually provided by an motor-driven generator, may alsobe found in many high-rise buildings. The building systems that receive power from theemergency system will vary and are usually dependent on the code requirements ineffect when the building was constructed.

In older buildings, the emergency power may supply only exit lighting in the stairshafts. I11 newer buildings, it may serve a large number of fire protection or life safetyfeatures such as fire pumps, elevators, and smoke-removal systems. Emergency poweractivation may be automatic when normal power is interrupted. or it may require manualactivation by using switches. During pre-incident planning inspections, be sure to



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determine if the building has emergency power, what it supplies, and how it is activated

ElevatorsUnder normal conditions, elevators are the only practical method of moving betweenfloors in a high-rise building. Under fire conditions, elevator operation can become very

erratic and extremely dangerous. Many of the control components of elevator systemscan be affected by smoke, moisture, and heat that are present during a fire situation.Safe use of elevators under fire conditions requires:44. Knowledge of how elevators work45. An understanding of what malfunctions may occur Familiarity with Standard

Operating Guidelines and their use under emergency conditions

A department-wide policy regarding the use of elevators during fire conditions should bedeveloped and adhered to by all department personnel.

Hoistways are the vertical shafts in which elevator cars travel. In buildings with multiple

elevators, all the elevator cars in a bank are usually in a common hoistway. Somehigh-rise buildings are equipped with low-, medium-, and high-rise bank elevators, alsoknown as split bank, that are configured so that some elevators serve only lower floorsof the building while others serve the upper floors. It is important to know whether or notthe building does have split-bank elevators and, if so, which floors the different banksserve. This information can be critical to making a decision about whether or not it issafe to use the elevator system.

The hoistway is separated from each floor by a hoistway door that is opened bymovement of the elevator car door when the car is level with the floor landing. Smokeand heat under pressure at the fire floor can enter the hoistway, even though the

hoistway doors are closed and travel up or down the hoistway. If a large volume of fireenters the hoistway shaft, the shaft acts like a chimney and draws the fire upward wherethe heat may be sufficient to ignite materials on upper floors next to the hoistway. Asheat and smoke rise within the hoisnuay, pressure will force it out the hoistway doorsonto the upper floors.

Elevator cars will burn, even to the point where hoisting cables can fail, causing the carto fall within the shaft. If fire has penetrated an elevator car or the hoistway, it isimportant that personnel be assigned to floors above and below the fire floor, includingthe floor where the shaft terminates, to check the spread of fire or smoke.

Almost every high-rise building is required to be equipped with elevator emergencyservice features that will automatically move the elevator cars to specific locations underfire conditions. The feature also allows fire fighting personnel to place the elevator carsin a "Firefighter Service" mode that provides specific safety features. Automatic recallmay be initiated whenever an alarm device is activated. Manual recall can be donethrough recall switches located in a lobby control panel or a fire control room. Automaticor manual recall of elevators is important for several reasons:



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46. It prevents smoke from entering the hoistway because it keeps the car from beingheld at the fire floor.

47. It reduces the possibility of occupants being trapped in an elevator car.48. It provides fire department access to the elevator cars if a decision is made to

use them.

The decision to use elevators during a fire in a high-rise building is one that must betempered with good judgment. While it is true that using the elevators will speed upinitial investigation and fire control efforts, an elevator malfunction that causes responseto a non-selected floor can result in fire fighting personnel losing their lives. Therefore,using stair shafts is the safest method of ascending to the fire floor. The decision to useelevators should be based on assurances that the elevator lobby on any involved floor issafe and that the elevator cars that are used are not physically capable of reaching thefire floor (split bank). Fire personnel already on the fire floors can confirm that theelevator lobbies at those floors are tenable.

Even when assurances are in place that elevators can safely be used, any additionalsafety features or procedures should be employed. These include the use of split-bankelevators that terminate at least five (5) floors below the lowest reported fire floor. Onlyuse cars that allow firefighter service. In addition, all personnel riding in elevator carsshould wear full-protective equipment and have forcible entry tools, a means ofcommunication, an extinguisher, and a knowledgeable firefighter assigned to operatethe elevator car.

All fire fighting personnel should be well trained in the operation of firefighter servicecontrols on elevator cars. The time to conduct this training or to develop departmentpolicies regarding emergency use of elevators is not the day of the fire.

Smoke Control, SystemsSmoke and its toxic products account for more than 80% of the fire deaths in the UnitedStates. Plastics greatly increase the volume and the toxicity of smoke. For example,polyvinyl chloride (commonly known as PVC) produces 500 times as much smoke asred oak. High-rise buildings, like most occupancies, have contents that arepetrochemical products that produce large amounts of smoke and toxic gases.

The forces that affect smoke movement in a high-rise building include the stack effect,expansion, wind, and HVAC systems. Smoke control can be either passive or active innature. Passive smoke control measures have been in use for many years. They consist

of:49. Barriers50. Curtains51. Gravity venting52. Smoke-proof towers53. Smoke removal shafts



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Active smoke control systems are relatively new. In addition to the methods of passivesmoke control that might be in use, active smoke control employs mechanicalassistance to route smoke in a planned manner. Active smoke control systems can beused to control the movement in many different ways. Some of these are:54. Stairway pressurization systems

55. Building smoke control system56. Zone smoke control systems57. Corridor smoke control systems58. Elevator smoke control systems59. Atrium smoke control systems

HVAC SystemsWAC systems are designed to provide conditioned air throughout the structure by a ductwork system. For reasons of economy and efficiency, these systems operate on theconcept of recirculating most of the air within the building. Under fire conditions, smokeor heat can enter the system at fire floors and quickly fill other parts of the building with

contaminated air if the system is allowed to continue in operation. When smoke andheat are pumped through the building in this manner, many occupants can be exposedto highly toxic gases and are placed in serious jeopardy, even though they may be onfloors remote from the fire. In a high-rise building with a recirculating air handlingsystem, the fire may be small, but smoke spread can be a major problem.

The air handling system in most new high-rise buildings is required by code to havedampers in the system. These dampers are smoke activated and control the spread offire products from the area of origin to other parts of the building. (Don't rely totally onthese dampers. In many cases, however, the building may not have dampers installed,or they may not function properly.)

Since the spread of fire products throughout the building is so critical in life safety terms,the best approach is to shut down the system when there is any doubt or concern thatthe system is contributing to the spread. Once the fire is controlled and the safety ofbuilding occupants has been ensured, the system can be reactivated if it has thecapability of exhausting smoke from the building.

The methods of shutting down the HVAC system vary depending on the particularbuilding. In some buildings, especially older ones, it may be necessary to close switchesthat control system air intake fans. Many times these switches are located in machineryrooms on upper floors of the building, or they may be located on the roof of the building.In many newer buildings and in some older buildings that have been modified, the airhandling system will shut down automatically under fire conditions. In some cases, theywill provide exhaust capability on the fire floor and pressurization of the floors above andbelow the fire floor.

Information about the air handling system in a high-rise building should be a critical partof pre-fire planning inspections. This includes how the system operates under fire



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The 2 -inch wet standpipe systems are required by code in all new high rise buildingsover certain heights. These systems provide a constant supply of water under pressurethat is adequate to produce effective hose streams on each floor of the building. Theprimary water supply source for these systems may be the domestic supply that can besupplemented by an auxiliary supply kept in a holding tank in the building. The 2 -inch

wet standpipe systems differ in design.

They may serve both 1 inch and 2 -inch outlets as well as the sprinkler system, ifthe building is so equipped. The necessary pressure and flow for a 2 -inch wetstandpipe system is usually provided by one or more fire pumps that serve as theprimary supply. Fire pumps for high rise buildings are usually multi-stage centrifugalpumps. They may be powered electrically or with diesel motors. These pumps aredesigned to produce the required flow at a pressure that is sufficient for working streamsat the highest point in the building. If an emergency or backup pump is required by code,there will be a backup system that activates automatically should power to the electricpump (s) fail. Backup pumps are usually diesel-driven. In many older high-rise buildings,

the water flow capacity in gallons per minute (liters per minute) is inadequate for the firepotential within the building.

Because wet standpipe systems must contain sufficient pressure to produce effectivehose streams at the topmost floor of the building, the pressure within the standpipes atlower floors must be reduced. This is normally accomplished by pressure-reducingdevices installed at each outlet. These valves are preset to provide the proper outletpressure for that location. Pressure-reducing valves have the advantage of being able tosupply multiple hoselines (within reason) while maintaining the proper pressure and flowrate. These valves control the pressure but can automatically adjust to varying flowsdepending on the size of the hose and nozzle or the number of hoselines. In place of avalve, there may be orifice plates in the outlet valve barrel. Orifice plates are stainlesssteel or brass washers with calibrated holes. These holes control the outlet pressure byrestricting the flow from the outlet. The plates are often tack-welded into the standpipevalve outlet barrel. The outlet pressure from these devices is not reduced until water isflowing. Pressure-restricting devices are yet another method of providing properpressure to standpipe hoselines. They reduce outlet pressure in much the same manneras orifice plates. The pressure-restricting device allows the valve to be opened only apredetermined distance. Firefighters who remove orifice plates or alter the setting ofpressure-restricting devices need to be aware that the outlet will then deliver increasedpressure from the system. Two drawbacks to the orifice plate and otherpressure-restricting devices are: These devices have no effect on static pressure. Theydo not allow for multiple hoselines because of the limited flowthat comes through the orifice opening. If orifice plates are removed to provide formultiple hoselines from an outlet, the pressure to the lines must be controlled at thestandpipe valve, and care must be taken when opening or closing nozzles.

Sprinkler SystemsSprinkler systems in high-rise buildings are now required by code in virtually every area



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of the country. However, there are many older high-rise buildings (maybe some in yourjurisdiction) that still do not contain sprinkler systems. There is no doubt that sprinklersystems provide the added degree of life safetv for newer buildings that is sadly lackingin older, non-sprinklered high-rise buildings. In some cases, retroactive legislation,enacted as the result of tragic high-rise fires, has mandated that older high-rise buildings

be fully sprinklered. However, these cases are the exception rather than the rule.Pre-incident planning inspections should take particular note of sprinkler systems whenpresent, what areas they serve, and how they can be supplemented.

Standard Operating Guidelines require initial response units to supplement any built-inwater supply system in a high-rise building during a fire. To do this effectively, firefighting personnel must be acquainted with the building, the water supply system, andthe location of fire department water supply inlets.

A fire department must have Standard Operating Guidelines for connecting to andsupplying the high-rise sprinkler system. Officers and pump operators must understand

the pressure and flow required to be supplied from the engine(s) supplying the sprinklersystem. Current national standards for supplying sprinkler systems should bereferenced.

CommunicationsWhen discussing problems that occur at emergency incidents, communication alwaysseem to be at the top of the list. High-rise fires are no exception, and communicationsproblems can he much more severe at a high-rise fire than one at ground level. In anytype of an emergency, good communications are vital to effective operations - maybeeven more so at a high-rise emergency.

It is a known fact that portable fire department communications equipment can beineffective or even completely unusable in a high rise. There are locations insidehigh-rise buildings where it is virtually impossible to transmit or receive messages usingportable radios. In some cases, satisfactory communications will cease with themovement of the radio location by only a few feet.

There is a definite correlation between portable radio effectiveness and the frequencieson which they operate. As a rule, radio frequencies in the VHF band are very ineffective.Those in the UHF band are fairly effective in most situations. Those in the 800megahertz band produce the most consistent results, although they are not perfect.Many new high-rise buildings and a number of older ones that have been retro fittedhave built-in emergency communications systems. These hardwired systems have

jacks at specific locations on every floor and, in some cases, even in the elevator cars,which allow fire personnel at different locations within the building to communicate witheach other.

Using the system requires plugging into it with a handset or headset. A number of



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handsets are normally kept on site. A built-in emergency communications system can beused as a primary communications channel if portable equipment is not functioningproperly. It can also be used as a secondary channel to avoid overloading firedepartment frequencies.

Built-in emergency communications systems are not the same in every high-risebuilding. Effective use of these systems requires pre-incident planning by firedepartment personnel on how the particular system works and how it would be usedduring an actual emergency.

Fire Control Rooms/StationsMost current codes require that newly constructed high-rise buildings contain a firecontrol room or station within the building. The room should provide, as a minimum:63. Specific information on alarms that have been activated.64. The status of fire protection systems within the building.

The information available at this location can be extremely useful for determining theexact location of a fire and the status of fire protection systems that may have activated.These rooms or stations frequently have communications systems that allow thetransmission of emergency alarms or instructions to building occupants and firefightersalike.

While there is much information available from a fire control room or station, it may notbe the best place to locate the IC for several reasons. If it is in a basement level, radiocommunication will probably be difficult. Positioning the IC at the fire control room mayalso remove that person from any face-to-face contact with other officers. In all cases,fire department personnel should be sent to monitor the information available at the fire

control room or station and relay it to the IC. This relay can often be established bycommercial telephone from the fire control room or station to the fire departmentdispatch office. As with other systems installed in high-rise buildings, fire control roomsor stations are not all the same. Monitoring the information that is displayed in theselocations or accessing the various systems that they contain requires some priorknowledge that can only be gained by pre-incident planning.

Life SafetyLarge numbers of people can be exposed to potential danger during a high-rise fire. Thisrequires that immediate attention be given to the issue of life safety. The following lifesafety issues must be taken into consideration by fire personnel when responding to ahigh-rise fire:65. Life safety can be enhanced by timely control of the HVAC system.66. Failure to control smoke movement within the building can put in any lives at

great risk.67. Evacuation takes time. Command staff must anticipate this time, and sufficient

personnel must be assigned to perform the task.68. The behavior of occupants during a high-rise fire is largely unpredictable.



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If occupants are going to be evacuated from the building, it is critical that they use stairshafts that are not contaminated with smoke and heat.

Fire Behavior and Fire Spread

At high-rise fires, command officers and operating forces must consider the following firebehavior and fire spread phenomena:69. Stack Effect70. Negative stack effect71. Vertical extension72. Core construction effect73. Fire loading74. Heat buildup

Stack EffectNormally, we perceive smoke as being heated and, therefore, lighter than the air

surrounding it. Thus, when we cut a hole in the roof of a small structure that is on fire,the hot smoke and gases easily exit the structure. However, this is not so simple whenwe are dealing with a fire in a high-rise building. Vertical shafts in a tall building tend toact as a chimney or smokestack by channeling heat, smoke, and other products ofcombustion upward because of convection. As this process occurs, a stratificationprocess also occurs in which hotter smoke moves toward the roof and the cooler smokestays lower. As long as the air inside the building is hotter than the atmospheric airoutside the building, ventilation will occur by having fresh air drawn in through lowerbuilding openings and discharged through the top. This is considered the "normal" stackeffect.

Negative Stack EffectWhen the outside air temperature is higher than the inside air temperature at thebuilding's upper levels, a negative stack effect may take place. Such a condition is morelikely to occur in warm climates. As the smoke leaves the fire area, usually by way of thestair shafts and other vertical openings, it cools. This effect pushes the smoke down thevertical shafts, or it settles to floors BELOW the fire. This situation may cause Staging tobe relocated farther from the fire or cause firefighters trying to reach the fire floor to useSCBA earlier than desired.

Vertical ExtensionTypical construction methods for high-rise buildings provide common avenues throughwhich fire may extend vertically. The three common methods of fire extension inhigh-rise buildings include the following:75. Auto extension76. Curtain wall extension77. Vertical shaft extension

Auto extension occurs when the fire generates enough heat to break out windows andthen fire "rolls out" of the fire floor and up the outside of the building. Heat is transmitted



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to the floor above causing the window glass to break and combustibles on the floor toignite.

As previously discussed, most modern high-rise buildings are constructed of structuralsteel. Exterior walls (curtain walls) are attached to the structure. A space is created

between the floor assemblies and the curtain wall. These spaces are supposed to besealed during construction. Should there be faulty installation or heavy fire conditions,there may be vertical spread of the fire through this space. This is called curtain wallextension.

The following features are incorporated into high-rise design and construction thatcontribute to vertical fire extension:78. Stair shafts79. Elevator shafts80. Electrical chase ways81. Plumbing/electrical/data cable "poke-throughs" (holes created through floors for

cable or piping distribution)82. Air-conditioning supply/return shafts83. Mail chutes84. Trash chutes85. Access stairs (open, private stairways constructed for tenants who occupy more

than one floor of a high rise)

Core Construction EffectA fire that reaches the plenum area around the center core of a high rise can spread inthat plenum area. Firefighters entering the fire floor and advancing on the fire mayinadvertently push the fire around the center core. This may cause the fire to circle

behind the firefighters cutting off their escape route. When fire is predicted to be in theplenum area, firefighters entering the corridor from a stair shaft should remove theceiling tiles in both directions before advancing. This may allow the firefighters to see iffire is in the plenum area. A backup hoseline should be in place and operating in theopposite direction to protect the advancing crew(s).

Fire LoadingThe quantity of fuel that is available to a fire on any given floor directly affectsfirefighters' ability to gain fire control. Where fuel is limited, such as on a vacant floor, itmay be possible to mount a greater effort to keep the fire from getting by that floor.

Heat BuildupFire in high-rise buildings generates large quantities of heat. Unfortunately forfirefighters, this heat cannot be dissipated easily from the building. Usually, there is nomeans to ventilate the building effectively. This high heat also takes its toll on thefirefighter. The higher the heat, the more one perspires. Perspiration dehydrates thefirefighter and removes energy. Re-hydration at Staging is critical.



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High-Rise Strategy & TacticsFire fighting concerns in high-rise buildings are similar to those in smaller structures.The safety of occupants and fire confinement are paramount. These two missions areaccomplished with diligent search operations and aggressive movement of handlines.Extinguishing high-rise fires requires aggressive firefighters advancing 1 -inch to 2

-inch handlines. High-rise fires are extremely labor intensive and provide manyobstacles to rapid fire extinguishment. Strategic and tactical considerations for fightinghigh-rise fires must be implemented rapidly. Because of the operational problemsinvolved in controlling a vertically extending fire, containment on the floor of origin mustbe the main objective.

Studies reveal that flashover can occur at 10 minutes, and the loss of elevators typicallyoccurs approximately 20 minutes into the operation. The cause of elevator failure isrun-off water from hoselines entering the elevator shafts and shorting out electricalcontacts. Water usage at serious high-rise fires will result in elevator loss.

If possible, enough resources to handle the incident should be in place at the 20-minutemark. Serious high-rise fires require a minimum of three handlines. When necessary,this allows parallel lines on the fire floor and a line on the floor above to cover extension.

Poorly vented fires, fire load, large exposed areas, fire environment, fire floor location,and unreliable water supply dramatically increase operational problems in high-risebuildings. The fire environment may be severely affected by the following:86. Floor construction with drop ceilings87. Heavy, sealed windows88. Intense heat and smoke89. Limited means of ventilation

Water delivery must be maximized to attain the most effective cooling action. Theheight of the fire area requires the fire service to rely on an unreliable means oftransportation during fire fighting operations. Access to the fire floor can be delayedwhen a fire is above ground. Firefighters are at the mercy of elevators and theprobability that they will not operate properly during fire operations. The task of multifloorascent via stairwells will slow down operations considerably.

Strategic Operating GuidelinesThe following are suggested basic Strategic Operating Guidelines that may be used at ahigh-rise fire. They are listed in order of importance. Locate the fire. Determine the firefloor location(s) as rapidly as possible. All future actions hinge on this vital piece ofinformation. Determine the specific fire floor (if possible) or the floors on which smoke isreported from any information that is available to you in the building lobby. Frequentlv,(especially during off business hours) specific fire floor information will not be availableother than a report of smoke on numerous floors (e.g., 20th to 35th floors). Verify the firefloor information received from responsible occupant/building management personnel orfire control or alarm display panel. Firefighters will have to interpret what the alarm panel



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is indicating such as activated heat detectors, smoke detectors, or sprinkler heatactivation.

Relocation of occupants or evacuation. During the early fire stages, especially if there isa rapid spread of fire products to floors above the fire area, it may be best to relocate

occupants from upper floors to safe refuge areas below the fire, rather than attemptingto evacuate them from the building. When this is done, it is critical that the occupants beplaced in areas that will not be subject to smoke or heat from the fire. If a decision ismade to evacuate the building, begin the process of controlling evacuation as soon aspossible. This may be difficult as occupants of numerous floors may have self-initiatedevacuation causing almost a mob scene or near panic in stair shafts or lobby. Anescape route from the area must be maintained, and responsible personnel such aspolice, floor wardens, or building security must remain along the route to prevent panic.

As well, due to large floor areas or maze-like corridors, occupants on the fire floor maybe unaware of the fire until it is too late to evacuate. The search of large areas will berequired. As soon as possible, search and evacuate the floor above the fire.

Access, identify, and gain control of the building systems. These systems include thefollowing:90. Elevators91. HVAC systems92. Communications equipment93. Fire pumps

Confine and extinguish the fire. Experience indicates any serious fire will require a largecommitment of personnel and equipment because of extensive logistic problems and aneed for frequent relief of personnel. Judicious placement of hose streams willfacilitate the confinement and extinguishing phase. Companies must be intimatelyfamiliar with high-rise buildings in their districts. Engine companies that are aware of thelocation of standpipe- equipped stairwells will accelerate procedures required to placewater on the fire. Smoke or severe fire conditions may exceed fire suppression capacityor delay entry to the fire floor. This can occur even when two handlines are operating.Critical decisions will have to be made by the IC when the fire is beyond the control ofinitial attack methods. The following options are available for consideration:94. Operate a large-caliber water appliance into the fire area from the stairwell on the

fire floor.95. Open the floor below or ceiling above the fire floor, and direct water into the fire

area. (This is very difficult to facilitate.)96. Prevent radiant or conductive heat ignition by flooding the floor above the fire with

hoselines operating from the stairwell. This procedure will not be effective onhidden fire.

Control extension to floors above. The number of personnel and hoselines needed fordeployment on the floor above to accomplish this will vary depending on the size of thebuilding and the severity of the fire conditions.



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A High Rise Primer

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Transcript of A High Rise Primer