Home | Index  

While non-combustible materials may not actually burn, significant fires may still result in partial or total failure.  Pipe columns such as this are quite common in reinforced masonry, fire resistant and non-combustible styles of construction.  If capped with a solid steel plate at top and bottom, they, become an enclosed cylinder subject to the same type of failure under intense heat exposure, as any other closed container lacking a pressure venting mechanism.

Firefighters should inspect any building undergoing extensive remodeling, to insure the integrity of fire resistive construction features.  This is a diagram of a remodel of a six story brown stone.  A significant portion of the bearing wall on the second floor was removed and replaced with a steel I beam to support the bearing wall above the second floor.  This I beam was then supported by a pipe column which was unfortunately placed directly over a duct opening and a doorway.  This point loaded the weight of the bearing wall on the third through sixth floors directly over construction features which were not designed to support that much weight.  This resulted in a collapse of a significant portion of this six-story brownstone.

Even if the collapse of not occurred, the removal of the bearing wall on the second floor eliminated its ability to act as a fire division wall and it is doubtful that the steel I beams would have been fire protected

Firefighters should make mental note of any occupancy containing High Rack storage, as these systems present a number of problems in a fire.  First, they may obstruct the spray pattern of the sprinkler system if the occupancy is so equipped.  Second, being of unprotected structural steel, any direct flame exposure or high heat may cause collapse of the steel supports and bring the contents down.  Third, these systems are sometimes inadvertently overloaded beyond their designed weight carrying capacity further increasing the likelihood of collapse in fire conditions.  Fourth, these racks separate the stored contents and provide maximum surface area exposure to the advance of a fire.

Firefighters should be aware that mobile homes are built to much lower code requirements than conventional wood frame construction.  Hence “bearing” walls (and that term can only be loosely applied in light of the minimal materials used in the construction of these buildings) may have two by two studs, and floor joists and roof rafters may consist of nothing more than two by three or two by four elements.  Many of the older mobile homes were built with materials which did not require low flame spread ratings, and hence these materials will contribute to rapid flame spread within the structure.  This particular flaw has been corrected in more recent building codes for mobile homes.  Due to the lightweight nature of the roof of these buildings personnel should attempt vertical ventilation with extreme caution and may wish to consider the use of roof ladders to spread the weight of the personnel operating on the roof over a larger area to minimize the risk of going through the roof.

Any significant level of fire involvement should prompt the incident commander to consider defensive tactics since once damaged these structures have little salvage value and will almost always be removed and replaced.  Is such a low cost structure worth the risk of injury to department personnel?  It also raises the issue that we are entering a mobile home park which almost always has very poor access, poor roads, poor hydrant spacing and locations, minimal clearances between units, and very low value comparatively.  Since we are driving apparatus that in most cases are five to ten times the cost of these structures, our rigs are the most expensive exposure at the incident!  Hence, Engineers should consider more defensive apparatus positioning in mobile home fires than we have taken in the past.

“Fire Resistive Buildings” Up until the late nineteen forties most Fire Resistive buildings were “steel framed”.  This meant the building had a skeletal framework of steel columns and beams which supported the actual weight of the structure and its contents.  These structural steel load carrying elements were “fireproofed” by encasement in either concrete or tile.  The floors were normally “cast in place” concrete.  Vertical shafts such as elevator(s) and stairwells were enclosed in masonry materials which provided at least a one hour fire barrier, minimizing vertical extension of fires from one floor to the next.  While the slide indicates “adequate” standpipe systems, in fact there were a number of problems with the standpipe systems that existed in these structures.  First, the systems were normally not cross-connected. This particular flaw presented us with significant operational problems in the Cooper Arms high-rise fire.  This the reason departmental policies and procedures require at least one supply line be hooked into each Fire Department Connection (F. D. C.) of any standpipe supplied structure.   During walkthrough inspections personnel should check to insure that any standpipe system which exists in the structure is cross-connected, and if not, a note should be added to the Target Hazard Plan for that occupancy indicating that the system is not cross-connected!  Second, the standpipe diameters found in these early structures is smaller than that required by present day codes, resulting in inadequate fire flows in some cases.  Third, these early systems may not be backed up by in-house fire pumps.

These older structures did, however, have several features which work to our advantage in significant fires.  First, since cost-effective centralized heating, ventilating and air conditioning (H. V. A. C) systems and fluorescent lighting had not yet been designed, these buildings had to use natural ventilation and lighting which limited the floor size and required windows which could be opened.  This kept the occupant- and fire-loads to reasonable levels.  Second, interior walls were normally of masonry materials which served as one hour barriers to fire spread and provided Fire fighting personnel with points at which to anchor offensive attacks or make defensive stands safely.  Third, these buildings contained very few “poke-throughs”, minimizing vertical flame spread from one floor to the next.  Fourth, these buildings have solid exterior walls with comparatively small window area, which minimized exterior vertical flame spread from floor to floor.  All these features combined to minimize the speed of fire extension from one unit to the next on the fire floor and from one floor to the next within the building.  This contributes to our being able to get enough fire fighting resources onto the fire floor quickly enough to affect a knockdown before significant vertical extension can occur.  This is not true in the newer high-rises, which have lighter weight walls, central H. V. A. C. and fluorescent lighting (which required windows to be sealed units, which could not be opened for ventilation purposes), all of which contribute to larger floor areas, meaning more of a fire- and occupant load on each floor, and less inherent fire resistive construction features and materials.  These features increase the speed at which a fire can develop and spread, and reduce the time we have to get sufficient resources onto the fire floor, before they find themselves faced with a fire of such magnitude that they can’t effectively fight it, and have to withdraw to a higher floor to attempt to prevent vertical extension.

We have a number of older structures in the downtown area which have exterior fires escapes.   Fire personnel should keep a number of points in mind regarding the use of these exterior fire escapes.  First, due to the age of these systems their physical condition should be suspect.  If Fire personnel have to use them, they should place ground ladders against the building and not the fire escape railing, they should keep the number of both fire and civilian personnel on any one landing or stairway, and the entire system, to a minimum.  Firefighters should tread cautiously on each stair tread, and place their feet toward the outer edge of each stair tread, and move cautiously to minimize impact loading of the system.

If we have no choice but to remove building occupants via the exterior fire escape, they should be taken one level below the fire floor and returned to the inside of the building to continue their evacuation via normal means of egress.  This will minimize the number of people on the fire escape at any one time and also minimize the number of fire department personnel required to escort occupants completely out of the building.

Although the encasement of actual structural elements is not shown in this slide this is an example of what tile encasement would look like.

This slide is of the Blackstone Hotel in downtown Long Beach, in which we’ve had several fires recently including one second-alarm.  It is an example of a typical post-WW II concrete constructed high-rise structure with many of the features discussed previously of buildings of its era.  It is demonstrative of a number of buildings sited between Ocean Boulevard and Seaside Way.  The primary entrance, on the south side of Ocean Boulevard, is the addressed side and is considered “grade level”, and hence the first floor .  However, there are also entrances on the south side of the building (Seaside Way) two floors below, in many of these buildings.  Hence, there is often confusion as to which floor crews are operating on, which creates communications conflicts during incidents.  Personnel need to know the buildings in their first-in district, in order to minimize this type of problem.

Beginning in the early nineteen fifties, concrete framed structures gave way to steel framed structures due to economics until the mid nineteen-eighties when various forms of steel reinforced concrete construction became more economical..  The slide indicates sprayed on fireproofing is ineffective, and a health hazard.  In fact, the health hazard portion of this statement refers to sprayed on fireproofing which contained asbestos, which is not found here in Long Beach.  The claim that sprayed on fireproofing is ineffective is also inaccurate.  In fact, the First Interstate fire in downtown Los Angeles demonstrated quite clearly that sprayed on fireproofing, when applied properly is quite effective.  In that fire, temperatures of 2,400° were reached and sustained for several hours.  This exceeded both the temperature and time rating that the sprayed on fireproofing was originally certified for, and yet no failure of any of the structural steel elements occurred.  This was true even in a number of areas where sprayed on fireproofing had been damaged or completely removed during tenant renovations on several floors.  They’re also other documented cases of such sprayed on fireproofing performing well in significant fire exposures.

In an effort to reduce weight and thereby lower cost, lightweight structural elements such as “bar joist” trusses supporting floor systems have replaced earlier and more fire resistant beams in newer buildings.  As in any other form of construction lighter weight structural elements are inherently less fire resistant than the heavier elements they have replaced.

The advent of fluorescent lighting and centralized heating and ventilating and air conditioning (H. V. A. C.) systems has also permitted significantly larger floor areas, leading to much higher fire- and occupant-loads on each floor.  As a result of these innovations, it was now more efficient to keep the building completely sealed, meaning windows could no longer be opened.  This complicated ventilation operations and also significantly increased the phenomenon known as “stack effect”.  Centralized H. V. A. C. also complicated Fire fighting operations by creating extensive networks of ductwork, which often cover several floors, resulting in more “poke-throughs”.  This significantly increased and expedited the movement of heat and smoke from the fire floor to other uninvolved portions of the structure.  One of the first actions of firefighting personnel upon arrival should be to gain control of the H. V. A. C. system in order to shut down either the zone which covers the involved portion of the building, or the entire system if necessary.  If the system is built with fire rated dampers, they can be used to control the movement of heat and smoke through and out of the structure.

Newer structures contain more utility and phone conduits increasing the number of poke-throughs.  During this era we also began seeing the advent of “curtain wall” buildings in which the entire exterior of the building was sealed in glass panels, or masonry and glass panels.  These panels were connected to the ends of the floor systems with either two (2) or four (4) bolts.  In some structures the seal between the end of the floor system and the curtain walls is very irregular, providing another means of vertical extension for heat and smoke.  Even in cases where the seal was good, the glass in these panels possesses very little fire resistance, and normally peels away quite easily under fire exposure, significantly increasing the vertical extension on the exterior of the building.

Another method of reducing weight, and thereby cost, was the replacement of masonry materials formerly used to enclose vertical shafts with gypsum board (drywall).

Around 1980 the advent of post-tensioned concrete shifted the economics of construction away from steel frame and toward the more predominant use of concrete materials.

This slide should more accurately be titled “Steel Reinforced Concrete Moment Resisting Frame”, as all the various structural elements of the various construction styles are in fact steel reinforced.  This steel reinforcement takes the form of reinforcement bars A. K. A. “rebar”.  The floor systems can take a variety of configurations some of which are diagramed in the upper left.  Corrugated steel decking (Robertson decking) with light weight concrete topping was the most prevalent form and is the most commonly found here in Long Beach.  Once the structural framework of the building is completed the exterior surface can be weather sealed with masonry or stone inlaid materials or a variety of preformed panels which are then bolted to the exterior of the building.

An earlier method of exterior curtain wall sealing consisted of using an extruded aluminum framework into which were placed either steel and, or glass panels.  An example of this style of construction is the Public Safety building north of Fire Station One, on Broadway in the downtown section of the city.  Knowing the approximate era of these types of construction features will allow personnel to begin to gauge what other construction features may be present before they even enter a building.  This type of sizing up knowledge may be invaluable in situations where you are about to fight a fire in a building you haven’t had an opportunity to pre-plan.

The problem with these extruded aluminum frameworks is they have a low tolerance for heat and hence under fire conditions will peel off the side of the building, providing an avenue for vertical extension to the floor above, as well as a risk to personnel operating in the street below.

Downtown Long Beach High Rises on Ocean Blvd. this shot clearly shows the difference between a post-WW II constructed steel reinforced concrete structure on the right, the Breakers Hotel, and the new curtain wall style construction in the building to the left of it.  One advantage to residential high-rises is that all of the residential floors almost universally have the exact same floor plan from one floor to the next.  Fire fighting crews should familiarize themselves with the floor plan of the floor just below the fire floor before beginning operations on the fire floor.  Knowing the layout will increase their safety and operational effectiveness.

Residential high-rises possess another advantage, fewer poke-throughs.  This is because most residential units contain their own individual HVAC system, or a localized zoned system that covers only a few units as opposed to commercial/office high rises in which the HVAC system will cover an entire floor, or several floors.  Commercial/office high rise floor plans also usually vary from one floor to the next.  Residential high-rises can also be thought of as “center hallway” in design in that normally every unit on either side of the hall is on an exterior wall in order to provide a view.  This greatly simplifies ventilation operations, as opposed to commercial or office high-rises, which may contain interior office spaces, where ventilating to the exterior requires ventilating across an entire floor from one stairwell to another.  Finally commercial or office high-rises often contain open floor plans with half-height walls or cubicles, instead of full height walls.  These open floor plans greatly expedite extension of fire across the entire floor.  These newer curtain wall type buildings also shed their exterior coverings, more quickly, resulting in more rapid vertical extension. 

This raises another cause for concern with these new curtain wall buildings.  Shedding their exteriors creates flying debris which can travel for blocks.  Hence, apparatus should approach and take up protected positions if at all possible, and Engineers should do everything possible to cover exposed supply lines to the standpipe inlets.  They should be in full PPE, and should have the compartment door next to the pump panel raised, and stand under it for added protection.  If possible, personnel entering the building should enter from a protected passageway under the structure, underground parking, utility corridors etc., in order to minimize their exposure to falling debris.

Park Tower. Bordered by P. C. H., Anaheim and Clark.  This building is an excellent example of why crews should conduct target hazard inspections.  Two of the upper floors of this building are owned by the same company.  The owner decided to have a central atrium open to both floors, served by an unprotected stairway.  Since this stairway is not considered part of the required exiting it is not required by code to be protected.  Hence a fire on the lower of the two floors will very quickly extend to the floor above.  Based on the exterior appearance many individuals assume this building to be steel framed.  It is however Steel reinforced concrete.  This can be easily determined by popping one of the drop-in ceiling panels up and looking at the underside of the floor system of the floor above.  Crews conducting target hazard inspections should not hesitate to perform such visual inspections of void spaces, in order to guarantee knowledge of the type of construction of the buildings they’re working in.  So far, our discussion of steel reinforced concrete construction has been limited to structures which were “cast in place”.  This type of steel reinforced concrete construction is very rarely ever seen any more.  This is due to the costs associated with all of the formwork as well as the extended cure times required before the structure could be occupied.  For this reason steel reinforced concrete cast in place style construction gave way to newer generations of steel framed structures.  But, eventually newer steel reinforced concrete technologies came to bear, one of them being the use of pre-cast steel reinforced concrete structural elements which are created off site at a factory, trucked to the construction site, lifted in place by a crane, and attached to the other structural elements already in place.  These pre-cast structural elements can take many forms as are shown here.  Single “tees”, double “tees”, flat planks, load bearing wall panels, beams and columns can all be pre-cast In whatever size, length, or configuration required by the building’s design and ultimate use.  As a side note, this type of construction performs very poorly in earthquake situations.  At present in Long Beach, the only pre-cast structures in use are parking garages.

The examination of the “tee” and “double tee” (diagramed on the right side of the slide) shows a characteristic which is common to pre-cast elements.  Because these elements are normally built to be supported at their ends only, reinforcing steel (rebar) is normally found only at the bottom of the stems of the “tee” or “double tee” elements.  As with any other simple beam, once loaded, the top, (in this case the wings of the “tees”), will be compression loaded while the stem or bottom of the beam undergoes tensile loading.  Since the only reason that reinforcing steel is added to concrete is to give it to the ability to withstand tensile loads, the only place where it is needed is in the area carrying the highest tensile load, mainly at the bottom of the stem of the beam (“tee”).  Therefore, this is the only location where reinforcing steel will normally be found in pre cast structural elements.

This information becomes critical in heavy lift or shoring applications when you’re working with pre-cast structural elements.  Since they’re designed to be supported at the ends only, any shoring or lifting done mid-span from underneath, would reverse the forces the beam is designed to carry, placing the stem in compression and the wings in tension, causing the “tee” (beam) to crack and fail directly above the lift or shoring points.

Pre-cast is also known as pre-tensioned because of the way it is formed.  Once the form of a pre-cast structural element has been decided upon, forms are built in which the reinforcing steel is placed prior to the concrete being poured.  The reinforcing steel is placed under the proper tensile load, and anchored at each, and the concrete is then poured into the form around the “pre-tensioned” reinforcing steel.  Once the concrete has cured to the proper level, the pre-cast element is released from the form, and trucked to the construction site.  This combination of pre-tensioned reinforcing steel and concrete forms a truly composite structure (the combination of two or more dissimilar elements, utilizing the strengths of each material to complement the whole, or make up for the weakness of the other elements to form a stronger final element).  Since the concrete is cured around and adheres to the reinforcing steel, which is already pre-tensioned, it maintains the tensile loading in the reinforcing steel and the tensile loading of the reinforcing steel places the concrete under a compression load.

This is different from the second type of steel reinforced concrete construction which is still in use today, (shown on the right of the slide), the so-called post-tensioned form of construction.  The post-tensioned type of construction is similar to the earlier “poured in place” type of concrete construction in that formwork is built on site and the concrete is poured into that form work and allowed to cure for the required time.  The difference is, before the concrete is poured in post-tensioned construction, “conduits (tubes) are laid from one end of the slab to the other.  Once the concrete has cured to the proper hardness, high strength steel cable is run through the conduit.  This cable, properly called a tendon, is anchored at one of the slab, and a hydraulic jack is placed onto the other end of the tendon.  This jack is operated until the tendon is placed under the proper tensile loading, normally several hundred thousand pounds, at which point this end of the tendon is also anchored to the end of the slab.  By anchoring each end of this highly tensile loaded tendon against the end of the concrete we are in effect compression loading the concrete. 

This also creates a composite structure, but due to the higher strength of the tendon (cable) used, this composite element is considerably stronger than the pre-tensioned element we discussed earlier.  This added strength allows the structure to be designed and built using lighter elements, reducing weight, and therefore cost.  Hence, post-tensioned concrete is now the industry standard for new construction, as it is less expensive than other forms of concrete or steel framed construction methods.  We have a number of post-tensioned buildings in Long Beach, the International Tower, the Pacific Club and others downtown.

This style of construction does have some drawbacks for the fire service however.  As with pre-cast structures, it performs very poorly in earthquakes.  And, it contains less reinforcing steel than conventional concrete construction.  This becomes a problem for us in significant fires, as the concrete will spall, and may expose the tendons, which due to extremely high tensile loading, will fail upon exposure to high heat more rapidly than conventional reinforcing steel which is loaded at much lower levels.  Additionally, since the more efficient use of elements allows lighter weight elements to be used, as with all other forms of construction, a structural element of less mass carrying the same load as a more massive element will fail more quickly under fire conditions.

Finally, if during any operation, you need to cut through a concrete slab, and come across a hollow section (the conduit) with a steel cable (tendon) running through it, do NOT under any circumstances, cut that cable!!!  Doing so may precipitate localized, or possibly total collapse of the structure.  This is because these tendons are similar to lightweight truss construction, in that if one tendon fails, it overloads the tendons on either side of it, which then become overloaded and may also fail, and this progression continues until either a structural element strong enough to resist the added loading is encountered yielding a localized collapse, or if that doesn’t happen, until the entire structure has failed.  These conduits may be “dry-packed” in which the tendon will be visible once you break through into the conduit, or “wet-packed”, where the conduit will be filled with grease, to keep the cable from corroding due to salt air exposure near the ocean.

Additionally, once these tendons fail, they shoot out of the end of the concrete slab and fly into whatever is in their path.  There are documented cases of this happening.  In Anchorage Alaska, after the 1969 earthquake, a post-tensioned structure failed and cables shot across a four lane street and embedded into the building on the opposite side.  The parking structure for the convention center downtown is post-tensioned.  A maintenance worker making repairs to the concrete accidentally struck a tendon, causing it to separate, and one end peeled the concrete back seven feet before dissipating its energy.  In the process, the worker was struck by a piece of concrete blown off the deck at high speed, and was injured.

As the slide points out, until the concrete has cured to the proper hardness, should the construction site suffer a fire, there is a significant risk of the building collapsing.  Under such circumstances one of the first tactical priorities is to protect the falsework and formwork which is normally all wood.

The International Tower located on the southwest corner of Ocean Blvd. and Alamitos, downtown.  This happens to be a post-tensioned structure.  It has a characteristic feature which all post-tensioned structures possess, very thin floor slabs.  In conventional concrete construction, floors are at least six (6) inches thick, even the lighter “Robertson” decking (corrugated sheet metal pan, with light weight concrete poured over the top), the slab is at least four (4) inches thick.  In post-tensioned concrete buildings, the floor slabs will be no thicker than four (4) inches, and normally will be flat on the underside, no corrugations, no column capitals, no other irregularities to the shape of the underside are usually visible.  These thin flat floor slabs are usually a dead giveaway that you are looking at a post-tensioned slab.

In this building under construction notice the thin floor slabs, the lack of beams or column capitals, and the openings in the end of the slabs.  What kind of concrete construction is this?  Answer = Post-tensioned.  Notice also, the higher concentration of conduits where the floors intersect the columns, and the amount of formwork and shoring in place on the top floor.  This is what must be protected if it is exposed to a fire.

Notice the tendons sticking out of the conduits, this is another dead-bang giveaway that this is going to be a post-tensioned building. 

Unprotected Structural Steel “I” Beams supporting a lightweight metal building.  This type of construction is quite common in industrial and commercial areas of Long Beach and Signal Hill.  The term “Unprotected Structural Steel” should be an instant indicator of a lack of fire resistance.  Any building with steel structural elements which are not protected by either permanent encasement (masonry materials or concrete) or a sprayed-on intumescent coating such as Gunnite should be noted during walk-through inspections.  This type of unprotected construction will result in structural failure if the structural steel elements are exposed to extreme heat (anything over 850 degrees according to some references, which is reached very early in the average interior fire) or direct flame impingement for as little as 10-15 minute time frames (the more heavily loaded the structural element is, the quicker it will fail).  The presence of a full sprinkler system which operates correctly will normally double this failure time.

            Note the high fire load, stacked in such a way as to maximize the availability of oxygen to feed any fire which may start, causing rapid extension.  Note also that this fire load is concentrated under the peak of the roof.  The only structural feature which this building has which will work in our favor is the presence of fiberglass panels acting as skylights.  These will burn through quickly, ventilating the fire.

            Firefighters should keep in mind that this is a very inexpensive type of construction to build and replace.  Is it worth risking your life to save it, if no lives other than yours are at risk?

This is an example of conventional steel frame construction.  This type of construction was prevalent from the mid-1960’s until pre-cast and post-tensioned types of concrete building construction were developed in the late 1980’s, offering a more cost effective alternative. 

            Note the steel “I” beams supporting the floor system.  Large areas are divided by these beams into smaller areas, where smaller intermediate beams support the floor load in between the larger beams and carry it to them.  Still smaller beams further sub-divide these intermediate sections into even smaller areas.  The small beams act as transfer beams transferring their load to the intermediate size beams, which collect their load and also act as transfer beams transferring their load to the largest beams, which then transfer the load to the steel “H” columns, which then carry it to the foundation.  This is the structural steel skeleton of the building.

            A corrugated sheet metal steel pan is laid on top of the horizontal steel beams, and lightweight concrete is poured over this pan.  This forms the final element of the floor system.  This has become known within the building trades as “Robertson decking”, although this is a misnomer, like calling all photocopiers “Xerox” machines.  This corrugated sheet metal pan is usually sixteen gauge thickness, with from two-and-one-half to four (2 & ½ -4) inches of lightweight concrete poured on top.  Firefighters need to be familiar with this type of floor system, as it presents some unique characteristics in fires.  If you happen to be in a structure with this type of floor system, and the concrete is spalling upward at you, you are most likely one floor above the fire and directly over it.  The concrete is being heated from below, but the sheet metal floor pan is preventing the concrete from spalling toward the heat as it normally would in a conventional concrete building.

This type of floor system is diagrammed here.  In an effort to compete with pre-cast and post-tensioned types of concrete construction, the steel industry has helped to develop lighter and more economical (translation=less fire resistive) construction methods.  One of them involves replacing many of the small and intermediate steel beams supporting this type of floor system with “open web bar joist trusses”, as shown in the bottom half of the slide.  This is the type of construction which supported the floor systems of the World Trade Center towers, and which helped to contribute to their collapse.  As of the date this handout was written (early 2002), there are a number of buildings which use this type of floor system, but none incorporate open web bar joist trusses as support.  That advantage is tempered by the fact that the post-tensioned type of concrete construction unfortunately is prevalent in most of the newer high rises built in Long Beach, which poses even more risk of fire related collapse.

A view of the underside of a corrugated sheet metal pan floor system.

An identical type of floor system with sprayed-on fire resistive coating.  Fire personnel should familiarize themselves with the appearance of this material, in order to be able to gauge the structural element’s resistance to fire as they walk through buildings.

The Arco Towers These buildings and the World Trade Center across from it, are examples of “Curtain Wall” type high-rise construction, in which the exterior panels are bolted to the ends of the floor pan by either two (2) or four (4) bolts.  These panels can be all glass (the Arco Towers), or a combination of glass and masonry materials (the W. T. C.).  Some of these panels weigh up to five hundred pounds (as in the case of the W. T. C.).  Fire fighters should remember a number of points regarding this type of construction.  First, there are frequently gaps between these exterior panels and the end of the floor pan, allowing fire extension from a floor to the one above it.  Second, exposure to the heat of a fire can cause these panels to break away from the building, dropping debris up to a quarter of a mile out away from the base of the building.  Engineers should remember this when they place their apparatus for a working high rise fire.  They should also open the compartment door next to the pump panel and work under it as much as possible to gain further protection from falling debris.  Hose lines supplying standpipes will also need protection from falling materials which might sever the line(s) and rob the fire attack team(s) of water at a critical point in the attack.  Third, once these panels break away there is no barrier to the vertical extension of the fire to the floor above.  And, finally, in the case of all glass panels, even if they don’t break away, there is very little resistance to vertical extension by heat conduction and radiation.

In a few cases, the “glass” on the outside of these “curtain wall” type structures is in fact a polycarbonate (Lexan etc.).  This type of material doesn’t break, but also limits our ability to remove it during ventilation operations.  The only effective method of removing polycarbonate window materials is to cut it with a rotary saw with a carbide tipped (wood) blade.  A twelve-to-eighteen (12-18) tipped blade has been found most effective in tests conducted on these types of windows.

            Firefighters should attempt, whenever possible, to find a sheltered entrance into the building, through an underground parking structure, or utility access tunnel etc., to avoid being struck by falling debris.  And, the base should be positioned either in this underground area or far enough away to be out of the “fall zone”.

The Federal Building, N. W. corner of Ocean Blvd. and Magnolia Ave.     This is an example of a steel framed building.  The main thing to remember about this structure is that the Feds won’t grant us access to the fifth and sixth floors.  We have indicated that we can’t effectively fight a fire if we don’t know what is present, and they have indicated that they don’t care.  They were told it might mean letting the fire burn until it burned down to the fourth floor and stopping it there, and they indicated that was fine by them—your tax dollars at work!  Apparently they have documents and other property that we aren’t “cleared” for.  So, should this building experience a fire, we may have to let it burn to us on the fourth floor!

Shot of Elevator Lobby, indicating an elevator that serves floors 24 to 39.  The Dept. has a policy regarding the use of elevators in high-rise fires.  First, the elevator shaft should be checked for the presence of smoke by shining a light up the shaftway between the car door(s) and the elevator lobby door(s).  If no smoke is visible, the elevator can be taken to no closer than five (5) floors below the lowest suspected fire floor, if the elevator has a “Fire Service Recall” system.  The elevator chosen should have the star of life indicator (meaning it is backed-up by an emergency generator if the main power goes out).  The elevator should be tested to insure it is in the Fire Service Recall mode by pushing the floor button for the floor just above the floor you entered it on.  If the elevator doesn’t stop on this floor, the system may not be functioning properly and may be taking you directly to the fire floor.  If the Emergency Stop button doesn’t work, you should jam an axe or Halligan blade into the crack between the doors, and force the door(s) outward in their normal direction of travel.  This will activate a safety feature, and should cause the car to stop.  If it doesn’t everyone should have their facepieces on, with their regulators clicked in, breathing off of their SCBA’s, in case the door(s) open on the fire floor.  An extinguisher should be readied to discharge onto the fire floor to better protect the occupants if they are met with fire.  It may be necessary to press the emergency door closure button, located six (6) feet off the floor of the elevator car on either side of the door, on the same wall as the door(s).  This button overrides the electric eye circuit in the door closure mechanism, allowing the doors to close even if the door way is obstructed (obscured by dry chemical powder from the extinguisher).  At the same time, you’ll need to hold the floor button in until the door(s) closes.

Whenever possible, crews should choose to use an elevator that is banked, that doesn’t serve the fire floor.  This will insure that you cannot be taken directly to the fire floor.  One of the first actions of the first crew ascending a high-rise building in a suspected fire is to check the elevator lobbies and floors to insure that the elevators can be used up to the staging floor, once established, and report the conditions they find as they ascend.  Staging will normally be established two (2) floors below the fire floor, unless there is a floor a little lower that is more open and would provide a better staging location.  If there are building occupants which need to be evacuated, a “safe Refuge” may need to be established just below staging, and building occupants directed or escorted there.

Diagram of a high-rise building with elevator shafts shown.  This is to indicate that we should take the elevator that serves 1-6 if the fire is above that.  (NOTE: the diagram is drawn incorrectly.  The red elevator should serve the sixth floor, so that occupants could get off the 1-6 car and get onto the 6-11 elevator.)

Diagram of two (2) elevator cars side-by-side.  This is to show that if one (1) car is disabled for whatever reason, that in some cases a second car serving the same hoistway can be brought alongside and a transfer of car occupants can be made.  Note also the escape hatch at the top of each car into the hoistway.  If necessary, crews can go to the floor above the stuck elevator and gain access to the hoistway by cutting the plastic (Gibbs) guide block at the base of each door, that slides in the depressed tracks at the bottom of the door opening, and then push the bottom of the door(s) inward into the hoistway.  (NOTE: This must be done very carefully, as it is possible to force the doors too far inward and break them off of their rails at the top of the opening, causing them to drop onto the top of the elevator car below!)  Once this has been accomplished, a ladder can be lowered onto the top of the elevator car and occupants can be assisted up and out of the hoistway.  All elevator machinery must be shut off before any such rescue is attempted, in order to prevent the elevator car from moving during the rescue attempt.  This type of rescue evolution should only be done as a last resort, in cases of true medical emergencies (severe difficulty breathing or chest pain etc.), as this poses significant risks that should be avoided if waiting for the elevator service technician is an option.  NOTE:  These evolutions are for mechanical traction type elevators only.  They can be distinguished from hydraulic elevators by the height of the floors served (most hydraulic elevators serve only ground to third or fourth floor) which may be the entire height of the building or an express bank serving a portion of the high-rise.  Mechanical traction elevators also have their mechanical room at the top of the building, and suspend the elevator car by a series of cables, which are also connected to the counterweight for the car.  Hydraulic elevators have mechanical rooms at the bottom of the hoistway, and raise the car by means of a large hydraulic ram under the car which extends to raise it to the appropriate floor. 

Should a hydraulic elevator car become stuck, it is possible to lower it to the next lower floor by means of a small hydraulic valve in the mechanical room.  This will release hydraulic fluid out of the hydraulic ram cylinder, lowering the car slowly until it reaches the next lower floor.  The elevator door(s) in the elevator lobby may need to be spread slightly, in order to be able to visualize where the car is in relation to the floor.  Stop the car as close to its normal floor level as possible, in order to allow the doors to be opened without requiring forcing.

Before any of these evolutions are attempted, the occupants should be advised of what you are doing, and they should try the “Emergency Stop” button, and try opening the doors and allowing them to re-close slightly, as sometimes the door open safety circuit malfunctions and detects an open door (when none exists) and stops the car.  You should determine the last floor that someone entered the car and whether it was traveling up or down before it stopped.  Have a firefighter go to the last floor someone entered from, and work the door(s) open and closed slightly, and do so for each floor from there to where the car stopped.

Aerial Shot of City Hall. Many steel reinforced concrete type high-rise buildings were built with a “central core” where the elevator and stairwell shafts, and utility runs are commonly found This forms the main structural element (the backbone so to speak) of the building, and each floor is basically built out away from this core to columns along the exterior perimeter of the building, which can be built smaller than if this strong central core didn’t exist.  This reduced cost, and maximized the views from each floor.  City Hall is NOT an example of such construction,  In fact, the four (4) towers on the north, east, south and west corners of the building are the main vertical structural elements, with the floors suspended between them.

Steel Framed Building Under Construction.  For the last four-five (4-5) years I have been betting recruit classes that it was just a matter of time before we would see additional solid structural elements replaced by lightweight elements.  If you look closely, you will see that the intermediate beams in the floor systems have been replaced in this structure by lightweight open web trusses.  These structures, by being far more combustible, and far less fire resistive than the steel beams they replace, make this structure far more dangerous to fire personnel.  While we haven’t seen any of this type of high-rise construction in Long Beach yet, we have begun to see it in mid-rises built here!

Diagram of Structural and Non-Structural Building Elements.  Those components shown in yellow are non-structural, meaning they support only their own weight.  Those elements shown in gray are structural elements that support their own weight as well as other elements of the building.  Note the non-structural wall studs shown on the right.  This may be important, as will be shown a little later.  Note also the drop ceilings.  These play a significant role in fire extension.

Diagram of plenum space above drop ceiling. Note that the H. V. A. C. system has ductwork bringing air conditioned air into the living/working spaces, but exhaust air from these areas enters the plenum through the vent next to the light fixture, for return to the H. V. A. C. system.  This is what is called a common return air plenum, and it is open throughout the entire floor area, above the drop ceiling.  Should a fire start in the living/working space of this floor, it would be drawn into the return air plenum space and spread easily throughout this hidden void space.  This is one of the reasons that as soon as you enter a floor from the stairwell, you should pop a ceiling panel up and make sure the fire isn’t already over head before advancing any further onto the floor.  Should you not do this, you may find the fire has extended over your head and behind you in this void space, cutting you off from your means of escape.  This is also one of the reasons that the first arriving crews should gain control of the H. V. A. C. system as soon as possible in a fire with such as return air plenum space.

Most newly constructed commercial or office buildings, particularly high-rises have interior, non-bearing walls made of galvanized sheet metal studs, sheeted with drywall on both sides.  These walls serve as dividers between offices within an occupancy, or between occupancies.  Personnel should remember this feature, as it could help them escape a building safely, if the hallway they need to use to get back to the stairwell is now blocked by fire.  You may be able to simply break through these lightweight walls until you can either get around the fire and back into the hallway, or possibly even break all of the way through into the stairwell itself.

Additionally, if a fire occurs in a highly secured office space, and you are having difficulty in gaining access, you might be able to enter the occupancy on either side of the involved one, and break through one of these lightweight walls more quickly than trying to force the high security hardware of the involved unit!

Drywall broken through, into the exit stairwell. Normally, in high-rise construction you wouldn’t expect to find wooden studs, but the point is still valid.  You may be able to break through the type “X” or doubled drywall sheeting, into the exit stairwell, and escape the fire, rather than risking a run down a hallway with fire present.

Corridor Hallway After Fire. Note the severity of the fire based on the damage to the wall covering.  By code, exit hallways in these type buildings are required to have a minimum one (1) hour fire rating.  This includes the ceiling tiles of a drop ceiling.  Hence, upon entering any hallway from the exit stairwell, you should immediately raise one of the ceiling panels and check overhead to insure the fire isn’t burning in the void space above the drop ceiling, before proceeding any further into the hallway.  If there isn’t fire present, and you choose to advance down the hallway, make sure you replace the panel back into the ceiling grid properly, as it is part of the one-hour fire rated enclosure of the hallway.  To leave it ajar would void the one (1) hour rating, possibly providing the fire an avenue to extend into this void space, if it gets behind you.  Or, if you advance down the hallway without replacing the tile, and the fire advances through the void space above the ceiling, it may drop down into the hallway, cutting you off from the exit stairwell.

Diagram of Fire Entering Void Space Above “Membrane” Ceiling. This fire rated drop ceiling is referred to as a “Membrane” ceiling assembly in the fire code.  In some jurisdictions, it may be the only required fire protection for the structural elements directly above it, which support the floor above.  There are several problems with relying solely on this type of system as the only fire protection for these structural elements. 

First, fires produce pressure which may dislodge these panels, allowing the fire to extend into this void space exposing the unprotected structural elements to the fire.  Second, it is difficult to tell the difference between fire rated and non-rated panels.  So, when the building maintenance staff has to replace a panel, they go to Home Depot, find a fire rated panel which costs a dollar, and a non-rated one which costs a dime, and not knowing the difference, they try to save the boss some money, and buy the non-rated panel and put it into the ceiling grid.  Once they do, we have no way of insuring that the entire envelope is fire rated.  Third, a less diligent maintenance staff may take a panel out of the nearest maintenance closet, unaware of its fire resistive characteristics, and replace the broken tile in the public area, leaving the hole in the “membrane” in the maintenance closet, thereby defeating the integrity of the “membrane fireproofing”.

This is why “Membrane Fireproofing” systems are not allowed as the sole means of protection of the ceiling void space and the structural elements above ceilings in Long Beach.  If they are used, it is as a back-up to the other systems or features that are also in place.  If, during a walk-through inspection, you find a membrane ceiling assembly, and the structural elements above it are unprotected, call Fire Prevention and report it immediately for correction.

Shot of the scorch mark from heat coming through a poke-through hole for electrical conduit. Judging by the height that the scorch mark extends to, we can see that fires do produce considerable pressure, which will vent through every possible opening in order to reduce the pressure.  This is one of the means of vertical extension in multi-story buildings.  And, thorough overhaul requires that we check the entire floor area above the fire to insure that the fire hasn’t extended via one of these poke-throughs.

The First Interstate fire, in Los Angeles.This shot was taken early into the fire.  It can be readily seen that the windows have been burned out, and the fire is extending vertically to the floor above via the exterior of the building.  One of the features in this fire, that complicated fire attack was an open floor plan on the involved floors.  The office spaces consisted of cubicles with half-height walls, which left the area above these half-height walls open from one end of the floor to the other in several cases.  We have a number of office high-rises in Long Beach that also have this same type of open floor plan, with half-height walls.  You should make a mental note of any such occupancy you inspect, as it will allow any fire to spread horizontally unchecked much more quickly than if even lightweight walls extended from floor to ceiling.

Shot of the First Interstate fire later in the incident, several floors burning.  Another problem with the open floor concept is that the contents of the entire area constitutes the fire load.  Hence, we need to be able to apply enough water to absorb the heat produced by the entire mass of combustibles for the entire floor, rather than the fire load that would be found in the rooms that would be involved once we entered the fire floor, as would be the case if the floor were divided into separate office spaces with full-height walls.

Since it takes an extended time to get added fire crews and lines emplaced to handle the larger fire flows needed to handle a fire on an entire floor, the fire continues to advance at a rate faster than we can catch up to.  Hence, as with all large fires, the incident commander needs to “write off” any floor which is significantly involved, and move to one far enough above the fire to be able to have enough crews in place to be able to handle the volume of fire which may develop once it gets to their location.

The First Interstate the Morning After by the time L. A. City Fire Dept. got this fire under control, they had approximately three hundred and fifty firefighters assigned to it.  One of the lessons learned the hard way on this incident was to make sure you know where the fuel inlet for the in-house fire pumps are, and what quantity and of type of fuel it takes.  At one point during the fire, the fire pump ran out of fuel and crews lost pressure.  The pumpers were providing back-up supply to the standpipes, but there was a noticeable drop in pressure and hence firefighting effectiveness until the fire pump could be re-fueled and restarted.  This has resulted in all of the fire pump inlets in Long Beach being clearly identified with the type of fuel needed.  This is also why we have a policy of insuring that at least one charged line goes to every Fire Dept. Connection in any building that has a fire, and at least two charged lines go into every F. D. C. that has one or more attack lines actually working off of it, as you never know when something will go wrong and we will be supplying the fire flows rather than the in-house pumps.

A thorough knowledge of Building Construction may be the only thing that keeps you from becoming a statistic!  The people in the elevated platform appear to be out of the potential collapse zone of this building.  But, based on the type of construction (masonry) a ninety-degree wall collapse is a possibility.  Judging by the angle of the aerial ladder supporting the elevated platform, do you think the turntable supporting the platform is outside the collapse zone?  It doesn’t appear so!  So, if the wall does collapse outward in a ninety-degree pattern, are the people in the platform really safe?

You never know the one piece of information that may save your life, and the lives of your fellow firefighters.  Hence, you should strive to learn as much as you possibly can about as many different topics as you possibly can, throughout your entire career!
Home | Index