Fire and the civil engineer

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Fire and the civil engineer

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Fire and the

civil

engineer

R. F. LEGGET & G. W. SHORTER

W T H DISCUSSION

Reprinted from Proc. lnstn Civ. Engrs, 1972, 52 (August) 189-201 and

:

971, 50 (December) 467-486

0

_{The Institution of Civil Engineers. 1972}

The Institution of Civil Engineers G r e a t George Street, London, S . W . l

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DISCUSSION

Fire and the civil engineer

R. F. LEGGET & G . W. S H O R T E R

s are going to start. However, M r Shorter, myself or leagues were o n the site of the fires described as soon as n, and we therefore speak from the experience of seeing the

fires themselves.

s are associated with the design of engineering structures poration in buildlng design of fire prevention procedures ples is becoming increasingly important because of the nu nber of very tall buiid~ngs. These bring special problems ress the importance of the chin~ney effect.

1 separation of structural design from the general arrangements ore from fire protection features of design as required by build- disappearing-as it should. An integrated approach of fire precautions in civil engineering structures and ructural engineer and the architect must work s o closely.

75. The introduction of continuity into structural design as in buildings is leading

t o other aspects of general design that are demanding special attention. The prevention of progressive collapse is only one such feature. Since this can occur in a bad fire under extreme circunistances this aspect alone seems t o make it essential that the civil engineer must be involved in the fire protective aspects of design.

76. It is regretted that in

Q:

71 M r R. J. Hansen's initials were given incorrectly.

M r G . A . Wilson, Consultant

I have been interested in fire protection In the Port of London Authority for about

20 years. There is a London Fire Offices' Cornn~ittec and unless buildings satisfy their requirements the insurance rates are high.

78. Since 1950 there have been two sizeable fires in London, one destroyed a ware- house and the other a cargo shed about 400 ft long. The difficulty in dock work is that although the bullding may be designed to be fire-resistant, the contents arc frequently high risk. Fire drill is important and In London where a fire engine arrlves within a few minutes of a call, the standing instruction is that anyone who discovers a fire, immediately calls the fire brigade before attempting t o deal with thc blaze.

79. The cargo shed was full of general cargo, and although the fire englne a r r ~ v e d

in three o r four minutes the shed was completely burnt out. I n the case of the niulti- floor wareliouse, the firebreak wall through the building was a n effect~ve reduction of risk.

80. Although experience during the Second World War confirmed the importance

of firebreak walls, subsequently storage areas increased for operating reasons to over a million cubic feet.

81. Investigations with the Fire Research Station, the Fire Offices' Comnlittee

and users indicated that sprinklers would not be welcome because the damage created by water was often excessive, and it was decided that floor and roof ventilators to get r ~ d of smoke $hould be provided to enable firemen t o reach the site of the fire.

82. The University of Edinburgh is going to inaugurate a Chair and a Depart-

nient of F I I ~ Engineering.

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M r J. W. Baxter, G. Maunsell & Partners

I n D r Legget's experience have there been any examples of the chimney effect co bined with a tunnel fire? A tunnel can be a severe hazard. If a tunnel, particul a highway tunnel, is o n an incline and a vehicle catches fire, the consequences horrific because the chimney effect would mean that air would be drawn up t tunnel to feed the fire, and above the fire the air would be vitiated and when peopl tried t o drive away from it their cars would stop from lack of oxygen a n d the peo would suffocate.

84. I n such a development as the Place Ville Marie were special preca to isolate the buildings above the shopping complex?

M r D. H.

New,

G. Maunsell & Partners

Recently 1 saw a practical demonstration of the value of a firebreak wall. A fire broke out, due t o boiling fat being left unattended o n a gas stove in one of a pair of semi-detached houses in St Austell. Everything in the house was destroyed, but the presence of the party wall and prompt action by the fire brigade saved the other.

86. T h e value of prestressed concrete as a material resistant t o fire was well demonstrated during the construction of shop floors for the St Pauls Cray housing estate in the early 1950s. A series of squat floor beams, with hollow clay pots between, acting compositely with a concrete floor finish, and plastered beneath, were put under test at the Fire Research Station at Elstree, with a view t o obtaining a two hour certificate for the floor. I t was possible t o keep the test going for four hours and obtain a certificate for this increased period.

M r J. P. Bamber, FlCE

I had t o extend the runway at Manchester Airport and put the local A road in a tunnel. There could be n o connexion between the tunnel and the runway above. One does not want the aircraft to stop and drop fuel into the tunnel or vehicles underneath t o catch fire and damage the runway. The tunnel was fitted out t o make it almost automatic. There were smoke, carbon monoxide and temperature detectors which were all connected back t o the airport control office. It was considered that as soon as anything was detected the 'crossing gate' type flashing road traffic lights at the end of the tunnel could be changed t o red and that fire engines could be at one end or the other within 24 minutes. In three years there has not been any trouble.

88. In another unusual case a sewer caught fire in an old part of Manchester. I t was a fairly shallow brick sewer of about 18 in. diameter. The Gas Department had cut a main through and this had been damaged. When it caught fire it acted like a gas stove. I t was decided that the fire had been going for about ten days because the ground above was warm and the rain dried up immediately it fell. Also steam was coming out of the manholes lower down. I t was difficult t o extinguish the fire. I t was possible t o get into the main sewer and look up the branch sewer and see the flames, but the Gas Department had t o dig down on each side and cut off the main t o stop the gas escaping further.

M r Wilson

Are there any reliable fire detecting instruments which are actuated by smoke, light or heat? What area can be protected with this type of cquipment?

90. When the information is received, what action is taken? This involves the problem of insurance.

M r F. R. Dinnis, City Engineer and Master of Works, Edinburgh Corporation A serious underground railway firc occurred under Barcelona in September 1966. The railway runs east t o west and north t o south s o that the systeln forms a largc cross under the city. This railway carries many passenger and freight trains. It is a cut

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nd cover tunnel. There are strict ' n o smoking' notices on all the stations and in The fire was caused, or at least fed, by a freight train with oil wagons. The stopped the train where he thought best-in the station. Drivers of passenger ins on the other lines drove on, thereby saving many lives.

93. I an1 interested in bridge design and motorway structures. There has been at least one fire In the UK under a n elevated road structure constructed recently. Engin- e told that elevated motorways are a blot on the landscape and take up valuable

.

I think there is a current trend for schemes using the space under elevated ructures for other purposes. If there is anything but free air under an elevated ructure there may be great risks attached to it. Have the Authors any experience

that sort of thing?

94. There is much talk in the UK about the need for adequate fire protection, yet e incidence of fire in multi-storey car parks is very low. I think that current design des permit unprotected steel in some multi-storey car parks. Is this low incidence

fire true in other countries?

M r W. A. M o r r i s , F~re Resea~ch Stat~on

e 1969 the Fire Research Station has investigated three fires under motorway ges. Only one of these bridges was in use; the other two were In the construction 96. The first instance was a case of bad practice on the part of the contractor. It involved a bridge where there was little clearance between the supporting columns and the soffit of the bridge deck. They had to remove timber shuttering which had been around the bridge bearings and decided that the best way to do this was to burn it away using oxy-acetylene. The highly stressed concrete bearings were not badly damaged but the damage 10 the soffit of the bridge although local was fairly severe.

97. The second instance involved the storage of diesel fuel under a bridge. A re involving some 40 gallons of fuel resulted in damage to the underside of the bridge. 98. In road construction projects, bridges often provide sheltered locations in otherwise exposed situations and contractors often take advantage of this.

99. The third incident was also due to storing plant and materials under a bridge. I n this case a trailer mounted site hut had been parked under the bridge. The fire was quite large involving the hut, the trailer and some cylinders of propane gas. Damage was sufficiently severe for the bridge, which was carrying a trunk road over the motorway, to be closed for a period.

100. After a structure has been damaged by fire the Eng~neer will want to assess the damage and foremost in his mind will be the re-use of the structure. At the mo- ment this is an area where there are big gaps in knowledge. First, it is necessary to ascertain correctly the degree of damage. A study of the propert~es of materials at high temperature and a knowledge of their interaction in the performance of structural elements can help in the evaluation of the damage. If the damage is severe the next step is to consider the feasibility of repair and to decide on the repair method. It is important to remember when effecting repair that the reinstated structure must fulfil all its original functions, including that of maintaining fire resistance if this is a requirement. When one uses resin bonded mortars for instance in repair work one must consider that the repair might have to withstand another fire.

101. At least 20-30% of the fires that the Fire Research Station investigates are in buildings in the construction phase. Most of these fires are caused by carelessness and poor housekeeping, often in situations where there is apparently little to burn. Supervision is an important factor in avoiding these fires.

102. As engineer~ng structures become more complex the problem of repairing fire damaged structures is becoming more evident, becausc of the tremendous cosls involved in dcmolition and ~cconstruclion. I think that there is the opportunity for close links with the Canadian Research Station in this field.

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their academic life by including it as part of the curriculum in engineering courses. Engineers tend not t o consider fire until they are compelled to and often d o not appreciate the damage that can be caused in situations where the apparent fire risk is low. Mr J. M. Fenton, FlCE

I n 1968 the Fire Offices' Committee issued the 29th edition of their Rules for Automa- tic Sprinkler Installations making widespread increases in the degrees of protection required. Firemasters of local fire brigade authorities have also tightened their approach to automatic emergency lighting, escape routes and fire exits.

105, The chimney effect of lift shafts in tall buildings is of great importance. Splitting flights into different shafts of ten storeys or so could help to localize a fire but by suitable construction and lining of the ground-to-roof shaft to give three-hour protection a fire could be confined t o the shaft itself and high protection afforded to the occupants of the building.

Mr Wilson

In the National Building Code of Canada are there any regulations for carrying out drills and trials for evacuating people, or is it merely accepted that it would be good if they were carried o u t ? If there is a large fire risk, unlcss there is a mock exercise one does not know exactly what it going to happen.

Mr S. Rogleff, Senior Research Engineer, Commonwealth Exper~mental Building Station

Civil engineering structures, other than buildings or warehouses, seldom appear to be involved in major fires. This tends t o result in a discounting of the particular danger, but the Authors focus the attention of the civil engineer back to the hazard. 108. Information regarding major fires on civil engineering works in Australia is meagre. There may have been fires in many civil engineering works, ~nainly during construction, but there is little information in the civil engineering literature.

109. A few years ago I studied the aftermath of a fire that caused considerable damage t o part of a heavy industrial plant. The affected part comprised a modern multi-storey framed structure of reinforced concrete that supported bins, hoppers, a system of conveyor facilities and one of the control centres of the plant. The structure was open, except for briclc walls around the control rooms only. The possibili- ties that the particular structure would be involved in a major fire had been considered remote, although the dimensions of the substantial reinforced concrete melnbers were such that they would have satisfied code requirements for s t r u c t ~ ~ r a l members with fairly high fire-resistance ratings.

110. T h e minimum con~pressive strength of the concrete in columns, beams and slabs was stated t o be 4000 Ib/sq. in. at 28 days. The coarse aggregates used were natural siliceous river gravel and crushed igneous rock. The thickness of most of the slabs was 8 in., and the dimensions of the beams and colun~ns ranged from 1 ft t o

3 ft in cross-section. The heights of columns were 12-15 ft and the spans of beams up t o 20 ft. The diameters of the reinforcing bars ranged between

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in. and 19 in., and the thickness of concrete cover was from I+ in. to 2) in., depending on the s t r ~ ~ c t ~ ~ r a l member. Unprotected steel ~nernbers supported the conveyor installations.

11 1. The fire started at ground level-a completely open area. This area had not been intended for storagc, but at the time of the fire twenty 44 gal drums of mineral oil and petroleum product4 awaiting re~noval were therc.

112. I t appears that thc fire was caused by a spark from a n electrical fault that caused ignition of mineral oil residuc accu~nulatcd close to thc base of one of the hoppers abovc a conveyor belt. The Arc sprcad to thc storcd d r ~ ~ l n s via thc c o ~ ~ v c y o r belt.

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Fig. 7 (left). One of the main columns at ground floor level ; spalling on the surface facing the seat of fire

Fig. 8 (right). Slab and beams above the seat of the fire; the extensive spalling exposed the reinforcement in the concrete slab

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113. The fire-fighting operations continued for about an hour, during which time

the structural damage t o the concrcte f r a ~ n c and floors, and to thc individual unprotected steel me~llbcrs, was substantial.

114. Thc extent of spalling of the concrete was cxtensive, as shown in Figs 7-9.

The avcrage depth of spalling varied between I in the 14 in., whilc the maximum depth was 2: in. The spalling of beams and columns did not expose the reinforcement, but the spalling of the exposed surfaces of the concrete slabs, particularly above the seat of the fire, extended beyond the bottom layer of reinforcement, leaving the rods exposed. Less spalling of the concrete occurred in sections where crushed igneous rock was used as aggregate, and it occurred mainly in the matrix, leaving the individual rock particles intact. I n those sections where river gravel had been used the spalling was pronounced, and across many pieces of the coarse aggregate.

115. Repairs to the structure after the fire represented a major undertaking. 116. I n recent years two fires of relatively short duration caused considerable damage to two Australian therrno-electric generating plants. Both started in the vicinity of steam turbo-generators, and both were apparently caused by the ignition of oil supply lines. Although quickly brought under control, the fires caused damage to the turbo-generating units involved and to their appurtenant plant. The damage to the surrounding engineering structures, air-conditioning system, and electrical and mechanical services was also considerable.

117. Warehouses and large civil engineering structures providing storage facilities are usually designed t o withstand large fires. Nevertheless some stored materials are considered t o be not dangerous or highly flammable, and the fire-resistance requirements for the structures to house them are often relaxed. A inajor fire in a raw sugar storage terminal in Queensland caused a n assessed property loss of approxilnately $A10 n~illion. T h e single storey 1000 ft long by 150 ft wide building of modern steel and concrete construction, without special fire protection, was destroyed. It had

Fig. 10. Milford Haven-damage to underside of pre-cast slabs protecting concrete deck above and damage to prestressed piles

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presumed that the probabil~ty of a serious fire in a building contain- Zar in bulk was so sl~ght that fire considerations should not unduly in- ign of the structure. The fire burned for five days despite the applica- ion gallons of water during the fire-fighting operations.

'housekeeping' can be very inlportant when structures are not designed

Harding, Consulting Engineer

opened a new concrete jetty at Milford Haven. While the first tanker to harged a steel pipe connected to a hose dropped and broke. Oil er under the jetty and caught fire. I was asked to inspect the e o n behalf of an insu~ance assessor.

.

Thejetty had been designed under the late Mr H . A. Henry for the contractor, wlem & Co. Ltd. Pre-stressed piles over 140 ft long were driven from self- led craft. These were 275 in. 0.d. and 20+ in. 1.d. T o simplify construction ater and avoid the expcnse of striking shuttering below the concrete deck with high tidal range there was a n ingenious arrangement. Light steel trusses to were cast in precast slabs which spanned the bents so that the deck was cast above this permanent form of shuttering and corporated the steel trusses.

121. The fire occurred a t high tide so only a short length of the piles was damaged. The underside of the precast slabs had been badly damaged exposing reinforcement. The lesson learnt was that by using this form of design the reinforced main deck had been con~pletely protected.

122. In 1931 the turbine house for the Ford Factory power house at Dagenham had to be be completed by a series of caissons and compressed air chambers while cooling water tunnels were being driven from a jetty in the river to the land. I n se of fire the main compressor shed had been built of steel scaffolding covered with eel corrugated sheeting. Duplicate electric supplies merged o n a switch board side the electricians' wooden shed alongside. Diesel compressors were also instal- led and on the jetty a second electric supply came off the main jetty contract.

123. In the middle of one winter night a n electrician who was working on a drum of transformer oil set his hut on fire whlch blazed and consumed both electric supplies. Fortunately the diesel compressors kept the caissons going while the second supply on the jetty with its separate compressors looked after the tunnel so there was no damage to the permanent works.

124. Alongside the shed was a considerable timber structure supporting three concrete mixers with loading plant. The cross-examination of the night staff the following day had ~ t s points of interest.

125. Why was the 3 in. dia. water pipe feeding the mixers not used? It ran under the electricians' hut so only steam came out. There was a flooded cofferdam a few yards away with a pump-but the pump was electric. Why were the several alr pumps not used? The hlgh pressure compressors were electric and there was a 5 ton derrick with 150 ft jib for unloading sand barges-it too was electric. Then why was the steam crane which fed aggregate to the hoppers not used? Unfortunately it ran on a timber gantry which had caught fire and the driver had evacuated.

126. Fords had refused to extend their road to the site so all material had to come by rail or water or on foot from the main gate. So when the fire brigade arrived they had to carry what portable extinguishers were available for nearly half a mile across the water front, by which time the fire was over. What is the moral?

Mr J. G. Frost, Consulting Eng~neer

The fact that there are few published papers referring to fire in relation to civil engineering structures may be evidence of the attention which fire protection has received in this connexion.

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128. Since publication of the Paper a fire has occurred in the Montreal Metro system in the switchover section beyond a terminal station. The origin of thc fire was electrical caused by a train of nine coaches bzing derailed through high speed switching which was against the operating rules.

129. The fire was minor to start with but spread rapidly, probably due t o the operation of the forced ventilation system. The result was loss of the train, severe damage t o the general area, loss of operation of the section of the Metro system for several weeks, estimated loss of $2.5 million and the death of the train operator. Fire fighting was hampered by dense smoke generated and spread through the tunnel by the ventilation system and the lack of water connexions in the area of the fire. This all shows that preparation for fire fighting in tunnels is necessary.

130. The Authors confined their attention to six major fires in certain projects completed or under construction. If all works under construction are considered civil engineering projects, I believe the list of projects damaged and delayed by fire would be endless. In my experience it is a rare project which does not suffer from fire damage in a minor or major way during construction. Fires in formwork during winter construction are not unusual. Fires due t o welding slag dropping on construction debris are common. Construction is generally considered a civil engineering responsibility and so the civil engineer must give consideration to fire prevention and proper housekeeping in connexion with his projects.

M r H. L. Malhotra, Fire Research Station

A great deal of attention is paid to fire protection measures for domestic buildings, offices, shops, factories and warehouses but only little for civil engineering works. The incidence of fires is relatively small but the Paper shows that fires occur and can cause a great deal of damage.

132. A recent fire involved the Menai Bridge. The steel structure was provided with a n enclosed tunnel covered principally with combustible materials including a great deal of bituniastic material. The lesson t o be learnt is that fires occur in the most unlikely places and there must be plans prepared for dealing with such emergencies.

133. Another fire took place in the cableways of the Battersea Power Station- also where normally a fire would not have been thought a hazard to be catered for. The presence of conlbustible insulation, a n enclosed tunnel situation and difficult access make such fires difficult t o deal with.

134. There have also been fire incidents involving concrete bridges during construction over new motorways. In one case the timber shutter close to a highly stressed bearing was being burnt off for quick removal and caused a fire responsible for only local damage which could have, if it had been more extensive, created a serious problem for the repair of the supports. I n another instance a builder's h ~ ~ t on fire under a bridge was responsible for damage to the concrete beams.

135. Fires can occur wherever conlbustible materials are present. It is the responsibility of management and engineers t o be aware of this and ensure that emergency procedures are available.

136. One problenl dealt with at the Fire Research Station is the assessment of damage after the incident and the remedial measures that may be taken. A research programme on the reparability of fire-damaged concrete structures has been initiated and it is expected that positive recon~mendations should emerge when the study is complete. The most important aspect is expected to be the quantitative assessment of damage suffered by concrete and steel during the fire and their residual strength properties.

137. Close links already exist between the Canadian Fire Research Establishment and the Fire Research Station in the UK. It is to be hoped that civil engineers are made aware of the need for fire protection by having this as a part of the curriculum. 1 9 6

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7 4 2 6

M r W. H. Paterson, General Manager. Subway Constructton, Toronto Transit

Cornrn~ss~on

ce is made to two fires in tunnels which the Authors say in

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61 'raisc thc most questions'. It is apparcnt that thc manner in which ventilat~on is providcd in

, i.c. the location of fan shafts and vcnt shafts in relation to points of acccss, significant in the event of a serious and i~nexpccted firc. The accumulation e and intense heat may create a barrier prohibiting the firemen from attacking 's apparent, therefore, that in designing the ventilation system in a tunnel .y to consider the location and size of shafts and ventilation equipment to necessary air changes at acceptable pressures and velocity to meet the 'lation requirements, and also to keep in mind the location of fan shafts fts in relationship to the points of access so that the smoke and heat, if at

be withdrawn in a manner that will help fire fighting crews. nt a research project is in progress to investigate and provide infor- o n ventilation and control of environment in underground rapid transit struc- Having in mind fires which have occurred in subways In America a research up has been asked to investigate and report o n design criteria for environmental control during emergencies in tunnels.

M r T. R . Durley, Consultant

Good fire prevention has developed a number of basic principles which cannot be ignored by the architect, engineer or building inspector. The National Building Code o f Canada seeks to provide safety to life and property in various types of structures. I t is a minimum requirement and must be changed as new construction materials are developed and their hazards made known. The Code regulates only the building and the general weakness is the lack of control over the occupancy. As a result combus- t~bles are introduced into buildings without thought of the amount of fire load or safety to the individual.

142. The fires in the Paper all violate one o r more of the basic principles of good

fire prevention. They are:

(a) combustibles should be kept at a mini~num in both the strttcture and its contents

(h) since the contents of most buildings are combustible, automatic fire protection usually in the form of sprinkler systems, backed by an excellent watcr supply should be mandatory

c) machinery and equipment should not be stored in any building in advancc of completion of the fire protective system; many losses occur through dis- regard of this principle

d) in any building adequate training should be made available to the operating and maintenance staff, visits should be made by thc local fire department and first aid equipment must be available o n all floors of the building, inspected at regular intervals and ready for instant use.

(e) equipment already o n fire should not be moved into restricted areas such as a tunnel whcre water and ventilation arc either not available or insufficient to handle the smoke which may be developed.

143. At the Montreal and Toronto railway tunnel fires, there was no water nor

suitable ventilation. In the Ottawa bridge fire a combustible deck of wood and asphalt and little or n o first aid equipment made the loss inevitable. The loss at Chat Falls powerhouse was fed by conlbustibles in the form of oil and compound. Lack of fireproofing the building steel and lack of a good water supply made the loss certain. The army warehouse and the hydro-electric plant at Kelsey were typical construction

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losses: combustibles in large quantity, failure to complete the fire protecti together with a roof adhcsivc of asphalt and unprotccted steel frame, wcre c factors.

M r H. A. Smith, Chief Engineer, Hydro Electric Power Commission o

Sharing the responsibility of the civil engineer involved in projects of the Hydro Electric Power C o n ~ n ~ i s s i o n of Ontario are architects, electrical and mechanical engineers and others. In many cases, the substructure and superstructure of a project may be reasonably safe from fire but not when the contents of the structure create a large fire load.

145. Ontario Hydro have structured into their organization continuing groups (or committees) responsible for establishing standards and procedures relative t o fire prevention and protection encountered in the design, construction, operation and maintenance of their many diversified plants. Since 1960 the construction of generating sources has changed from predominantly hydraulic t o fossil-fuelled, using coal, natural gas, residual and crude oil as fuels, and nuclear using the Candu principle, all with their corresponding fire hazards, many of which are different from those in hydraulic plants. T o maintain a high order of customer supply, considerable attention has been given to transformer stations. This involved the elimination of spread of fire between main transformers or other essential equipment which otherwise might de-energize the complete station with the resultant loss of customer supply.

146. Fire tests of various sizes are also a main responsibility of the conlnlittees. Some are undertaken to establish standards (e.g. transformer spacing and other fire prevention measures) and other small fires t o train staff in the detection of fire hazards and the use of fixed and portable fire fighting equipment. Training also uses audio-visual aids because it is vital for all staff to be aware of the ever-present fire hazard and the corresponding fire prevention, protection or safety standard.

I Messrs Legget and Shorter

The confirmation that the contributors to the discussion make t o our suggestion as t o the importance of recognizing the possibility of fires o n civil engineering works is welcome.

148. In the discussion there are nearly twenty further cases of fires on civil engineering works mentioned. M r Morris indicates that 20-30% of the fires studied by the Fire Research Station are on construction sites. This suggests that the subject matter of the Paper is not as infrequent as we thought a t first. I t makes all the more surpris- ing the lack of papers on this topic. In the publications of the American Society of Civil Engineers, over one hundred years, only one paper of significance has been found.13

149. M r Wilson showed the importance of the contribution to fires that the contents of buildings can make. The concept of the 'fire load' in buildings is now well accepted in fire protection engineering. It is a matter to which much current research is directed. The objections to the subdivision of large areas of warehouse space are understandable but anyone who has ever seen the satisfactory protection that can be given by a fire wall by dividing a large open space into conlpartments will appreciate that a judicious balance must be sought as between fire safety and operating convenience.

150. The indication given by M r Wilson of the establishment of a Chair of Fire Protection Engineering at the University of Edinburgh gives news that will be widely welconled. Canadian experience will be made readily available to those responsible for this development.

151. M r Wilson asked about instrumentation for fire detection. This is now an active subject, covering a wide field. In summary it may be said that there are a number of reliable detection devices available, the choice of a particular device depending upon the situation in which it will be used."

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7 4 2 6 he question raised by M r Baxter as to the possibility of the chimney effect combined with iires in tunnels, or underground spaccs, is scrious, especially in of the steady increase, at least in North America, of underground shopping s in urban complexes. Fire doors must be located at all strategic points, as ey are in the Place Ville Marie complex in Montreal, and they must be maintained normally closed position. There are few, if any, locations where accepted fire tion measures are so essential as in such underground spaces, since the chim- 11 be of serious consequence if temperature conditions are appropriate and in the reverse direction t o that normally experienced in tall buildings. e welcome M r Dinnis's reference t o the Barcelona tunnel fire; it is clearly unusual importance. We have had no experience with fires under elevated ures such as roadways but share Mr Dinnis's concern for this possibility. We ot know of any serious fires in North American car parks. This is probably ed with the open character of these structures but is also associated with the culty of getting a fire started with standing automobiles that are in good order, shown by tests carried out by the Joint Fire Research Organization.ls

154. The liaison between the Joint Fire Research Station (now part of the Building earch Station, Department of the Environment) mentioned by Mr Morris and Malhotra is only briefly referred to in the Paper

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70). However, for twenty years it has been a source of the greatest satisfaction t o us and our colleagues as it now continues to be under the Division of Building Research, National Research Council of Canada Directorship of D r Hutcheon. Similar close links exist between Canadian fire research work and that carried out by the National Bureau of Standards in Washington, DC. International liaison in the fire research field, supplementing valuable personal links, has been greatly assisted by the continuing work of Commis- sion W14 of the International Council for Building Research, Documentation and 155. M r Morris mentions the difficulty of determining how much damage has been done t o a structure by exposure to fire. Concrete, so widely used in civil engineering structures, raises the difficult questions since its appearance after fire may be no useful guide. Research is being carried out on this matter.16

156. The increased attention now being given by local fire authorities t o fire prevention measures noted by M r Fenton is t o be welcomed. Only by constant attention of this sort can fire losses be controlled. The chimney effect in lift shafts is a focal point in current research work into fires in tall b ~ i l d i n g s . ~ ~ * ~ ~

157. All we can say in answer t o M r Williams about leaking diesel oil is that we hope it is not a common experience; it is clearly dependent upon good 'housekeeping' which is so basic to all phases of construction safety.

158. The provisions for fire evacuation measures in buildings occupied by people, asked about by M r Wilson, constitute part of the National Fire Code of Canada,18 now under extensive revision. The Building Code covers all aspects of building related t o design and construction. Once a building is occupied, its safe maintenance is aided by the provisions of the Fire Code. Work o n the two docun~ents is done in close collaboration, there being a joint technical committee responsible for the inevitable points of overlap between the two documents.

159. The contribution of M r Rogleff was especially welconle as our links with the fire research work of the Conlmonwealth Experimental Building Station have been close, with valued reciprocal visits of staff.

160. The two fires described by Sir Harold Harding were unusual and of great interest. After the Paper was prepared, Mr G. B. Willliams, Senior Assistant Deputy Minister of Public Works, Canada, provided us with a list of wharf fires that have taken place on structures with which his Department was concerned. With his per- mission, this is reproduced a s Table I . It shows the importance of fires even with this type of civil engineering structure.

161. The Montreal Metro fire, mentioned by M r Frost, was a serious and tragic 199

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-

I able 1. Fires involving waterfront properties

Date Location

1

Description Cause

--

I

Loss, I I 25 October, 1960 3 July, 1960 Middle

/

Wharf Caraquct, NB

Tignish, Prince Breakwater Edward Island Electrical short circuit Unknown Unknown Smoking Unknown Internal combustion engine Smoking Unl<nown E x p o s ~ ~ r e to a fire Oxy-acetylene cutting Electrical short circuit Exposure to a fire Unknown 14 August, 19601 Lord's Cove, NB

9 June, 1963 1 Forestville, PQ 21 August, 1963 ' Little Cape, NB

1 I February,

₁

Quebec, PQ 1963

I

3 August, 1964

1

17 August, 19641 21 October, 1964

1

6July, 1965

,

' Wharf Wharf Breakwater Wharf

i

30 August, 1965! 30 August, 19661 I Saanichton, BC Wharf Terence Bay, NS Wharf Orleans Island,

I

Wharf

PQ Roddington, Newfoundland Point Edward, NS 31 July, 1967 5 August, 1967

Wharf and Shed Jetty ~'navista, New- foundland Douglas Town, Gaspe, P Q Anse St. Jean. Wharf Wharf Unknown lncendiarism ~hicoutimi; PQ Lower Caraquet, N R 8 August, 1967 Wharf Wharf ~ g z n t Bay Prince E d k d

1

Wharf Island I Petrol explosion 5 October, 1967 Green Bay, New-

foundland Pinkney's Point,

NS

Wharf and shed Wharf 8 December, 1967 Cutting torch Petrol vapours 30 000 Wood Islands, Prince Edward Island and propane heater

1

65 000 15 December, 1967 Wood stove heating and drying sand Exposure to a fire Welding-pctrol exposure to a fire Exposure to a fire Exposure to a fire Smoking Children, matches Exposure to a fire Exposure to a fire Smoking Wharf 40 000 8 530 1 50 000 14 000 5 570 53 000 5 000 73 521 11 150 95 000 31 March, 1968 13 May, 1968 Redonda Island, BC Port-aux- Basques, New- foundland

1

Wharf and pier Ferry terminal Wharf 30 May, 1968 Cocagne Cape,

N B Constance Island 28 June, 1969 Dock 14 June, 1969 9 September, 1969 Noel, NS Pilley's Island, Newfoundland Wharf

Wharf and shed 16 October, 1969 28 July, 1970 Miscou, NB Newfoundland St. John's, Newfoundland Tahsis, BC Wharf Wharf

Wharf and shed 4 June, 1970

(17)

7 4 2 6 happening. I t lasted for 24 hours. In view of the major elements in this case, involving the newest of North American subways (the first to be equipped with rubber- tired vehicles) it is hoped that it will be described in engineering literature so that

om this sad experience.

about the fire at the Menai Straits Tubular Bridge, and knowing ing of the critical effect it had upon rail transport to Anglesea, we are surprised e only reference to it was the mention made by M r Malhotra.

.

We know of M r Paterson's interest in safety in subway operation, and especi- nnexion with fire. The research programme he mentions is to be welcomed; cative of the close co-operation that is maintained between major transit r ~ t ~ e s in North America.

.

M r Durley, who has contributed much to the National Building Code and ational Fire Code of Canada, presents some of the more important principles fire protection engineering. We are sure he would be ready to recognize that not of the measures he outlines could have been applied to the structures noted in the per. However, it is useful to have his reminder of what should be done, when ssible and when practicable.

195. We are grateful to M r Smith for his summary of the active measures continu- ly being taken by Ontario Hydro in an effort to maintain the remarkable safety ecord of their extensive system, now supplemented by nuclear powerplants with their 6. We hope that the discussion generated by the Paper may be the means of tracting attention to this hazard on all civil engineering works and of preventing

that were not expected.

13. BROWN A. L. Fire safety measures can avoid costly construction failures. Civil

Etzgt~g, 1947, 7, Sept., 532-535.

14. It~tert~atiot~al Sj~n~posirltn otz alrtomatic f i e c/etectior~. Fire Research Station, Boreham Wood, 1972.

15. Fire atld car-park brrilclitigs. Fire Note 10, Ministry of Technology and Fire Offices' Committee, Joint Fire Research Organization, Boreham Wood, 1968. 16. HARMATHY T. Z. Determitlitlg the temperatrrre history of cotrcrete cot~str~rrctiot~s

follolvit~gfire exposrrre. Research Paper, 381, Division of Building Research,

National Research Council of Canada, 1968.

17. WILSON A. G. and SHORTER G. W. Fire atzrl high brrilr/it~gs. Tcchnical Paper 333, Division of Building Research, National Research Council of Canada, 18. Natiot~al Fire Cocle of Carrarla 1963. Associate Committee on National Fire

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Fire and the civil engineer

R . F.

LEGGET,

SM, FICE*

G.

W. SHORTERt

Introduction

Fire has always been at once the servant of man and a continued hazard to his living. H e has learned to control and harness fire for his 'use and convenience' and steadily to improve the design of his buildings so that they should be as 'fireproof' as possible.

2.

Building regulations have advanced greatly since the earliest legal precautions against the burning of thatched roofs. So complex have these technical documents now becoine that 'fire protection engineering' has already won recognition as an accepted branch of the profession. Fire fighting has become a highly proficient and expert public service. Lives are still lost in building fires, unfortunately, but mainly due to human frailty rather than because of building deficiencies.

3.

The civil engineer has played some part in this encouraging development. Many of his own structures, as they approach the character of buildings, are designed in conformity with modern principles of fire protection engineering.

It

is, however, essential that the possibility of fires occurring on civil engineering works be recognized.

Ordinary meeting, 5.30 p.m., 18 April, 1972. Written discussion closes 30 April, 1972, for publication in Procerdi~igs Part I after September 1972.

*

Former Director, Division of B u i l d ~ n ~ Research, National Research Council of Canada.

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L E G G E T A N D S H O R T E R

4. In reviewing twenty years' work in the field of fire research in always an important part of building research in the Dominion, the have had occasion to note the gap that sometimes appears to exist bet normal practice of civil engineering and that general appreciation of

tective measures now so general in building design. They have had direct experience of a number of serious fires which seem to illustrate this gap.

5. In order to see if this experience was unusual, the Authors consulted the impressive 150-year collection of Institution publications. In its century and a half of service, the Institution appears to have published only nine papers dealing in any way with fire and buildings or with fire research, and only two papers on fire fighting, but no papers at all on fire in relation to civil engineering structures or construction practice. A list of these papers is given in the Bibliography.

6. The Paper has been prepared therefore to place on the record brief descriptions of some cases of fires on civil engineering worlts known to the Authors, together with some suggestions arising from a study of these examples. Six cases will be described briefly, with comment and discussion following. All were accidental, as almost all fires are; all involved considerable property loss, and in one case unfortunate loss of life. It will therefore be appreciated that the Authors are particularly indebted to the authorities concerned for their constructive willingness to have their own misfortunes publicized in this way for ultimate public benefit.

Examples of fires in civil engineering works

M O U I I ~ Royal railway tunnel

7. The City of Montreal is built around Mount Royal (elevation 987) the upper part of which has been preserved as a magnificent natural park. 'The Mountain' is a serious impediment to traffic flow, although a beautiful civic feature. In 1918, it was pierced by the Mount Royal Tunnel, constructed by the Mount Royal Tunnel and Terminal Company for the Canadian Northern Railway, since 1923 a part of Canadian National Rai1ways.l This tunnel has its eastern terminal at the Central Station of the Canadian National Railways (now greatly enlarged).

8. The tunnel, which is approximately 3 miles long, was built to accom- modate two tracks; it runs in an

E-W

direction and was driven through lime- stone and essexite. Because of the varying distances of rock froin the ground surface, it was necessary to use different construction techniques at different locations in the tunnel. A portion of the tunnel (1650 ft) at the Central Station or eastern end had to be constructed with a concrete roof. This section was of twin arch form, the central concrete wall having steel colun~ns einbed- ded in it.

9. About 05.00 h on 12 January, 1946, a fire of unknown origin was dis- covered in two empty railway coaches, coupled to seven other coaches, standing in Central Station. The fire, which threatened to spread to coaches on adjoining tracks and t o the canopy over the rails, was quickly brought under control. It was decided, however, to move the smouldering coaches through the tunnel to the less congested western end. The driver of the diesel engine pulling the nine coaches did not see a work car in the tunnel, possibly because of heavy smoke, and crashed into it. The collision caused the remaining

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Courtesy : Canadian National Railways

Fig. 1.

CNR

Mount Royal Tunnel, showing damage to concrete block roof after fire

of

1 2

January, 1946 (overhead electric trolley wires have been replaced)

seven coaches to be set ablaze. The accident occurred about 1500 ft inside

the eastern end of the tunnel. Two of the men escaped from the work car

and started to walk towards the western end of the tunnel. Their bodies

were later found, overcome by smoke, about 1500 ft from the fire. Another

man sought refuge in

a

manhole near the fire but he, too, was overcome by

smoke.

10. The Montreal fire department was called at 05.05 h but was handicap-

ped in several ways in fighting this fire. The nearest source of water was in

the railway station at the eastern end of the tunnel, so that it was necessary to

lay many hundreds of feet of hose to get two lines of fire hose up to the blazing

cars. Ventilation was poor in the tunnel so that heat and smoke were a serious

problem. Firemen wearing masks were able to breathe in the smoke-filled

atmosphere but visibility was practically zero. Flood-lights were taken in at

the eastern end to improve visibility. Firemen also entered the tunnel from

the western entrance in an attempt to rescue any men who had escaped from

the burning cars and who might have been heading towards this entrance.

Unfortunately, visibility was again so bad that little progress could be made

and the rescue attempt was abandoned. It was not until 10 hours after the

fire had started that the Fire Department considered it under control.

11. The fire destroyed the nine coaches, the diesel engine and the work

469

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car. Rails were badly buckled, and ties were destroyed; the tunnel structure

suffered comparatively little damage despite the severity of the fire. The old

style wood-frame coaches, together with other combustible material, provided

a considerable 'fire load'. Structural damage was limited in the main to

some spalling of the concrete lining of the arch in the area of the fire (Fig. 1).

Property loss was estimated to be $250 000, and unfortunately four lives were

lost. The fire is still the only accident which has happened in the 50 year

history of this busy tunnel.

Dzterprovi1lcic21 Bridge, Ottawa

12. Ottawa, capital city of the Dominion, is located on the south shore of

the Ottawa River facing the slightly older settlement of Hull in the province of

Quebec. The first bridge connecting the two was a pioneer structure, joining

some of the rocky islands at the great rapid of the Chaudikre, built in 1828.

Not until 1900 was the secondconnecting link constructed, this being the Royal

Alexandra Bridge, now more commonly known as the Interprovincial Bridge.

Spanning the full width of the river, it was the longest cantilever structure in

North America when con~pleted.~

It was transferred by the Canadian Pacific

Railway to the Government of Canada in 1968, and is now maintained by the

Federal Department of Public Works.

13. The superstructure consists of a 1050 ft cantilever, two truss spans of

247 ft and 140 ft respectively, two spans of 27 ft and 32 ft respectively at the

Ottawa end, and a n approach trestle from Hull of 13 spans of 30 ft each

giving an overall length of 1896 ft. The approach trestle consists of deck

plate girder spans for the railway with two highway lanes on a 5% grade

from the Hull street level up to rail level. The deck of the highway section of

the bridge was of wood-and-asphalt plank constr~iction. Within 50 ft of this

approach trestle was a very large pile of approximately 20 000 cords of pulp-

wood in the large storage yard of the

E. B. Eddy Paper Company. Within

about 100 ft of the pulp wood pile was one of the company's mill buildings.

14. Shortly before 19.00 h on 29 March, 1946, a fire started at the northern

end of the bridge. The fire spread from the wooden bridge deck to the pile

of pulpwood. Before it was extinguished, it had caused approximately

$750 000 property damage, but no one was seriously injured during the blaze.

15. The fire was first noticed by a man fishing off one of the bridge piers

on the Hull side. He saw flanles along the edge of the wood planking and

turned in an alarm at 18.43 h. By the time the Hull Fire Department arrived

at the scene, the fire was spreading along the wooden deck of the bridge and

the huge pile of pulpwood was already starting to burn (Fig. 2). The fire

was able to spread easily from the bridge to the wood pile since there was dry

grass beneath the approach spans, grass that was oil soaked from a section of

conveyor chain laid on the ground for oiling.

16. The main efforts of the Hull Fire Department, assisted by the Ottawa

Fire Department, were directed to preventing the fire from spreading from the

pulpwood pile to the adjacent mill building 100 ft distant. The Ottawa Fire

Department assumed responsibility for stopping the spread along the timber

deck. Using saws and axes, holes were cut in the double planlc wood deck.

Firemen were lowered on ropes through these holes and played streams of

water on the underside of the bridge deck, which was coated with asphalt. At

times the flames, aided by a brisk wind, had passed the holes by the time they

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Fig. 2. F ~ r e at the Interprovincial Bridge between Ottawa and Hull, showing bridge deck and pile of cordwood alight (1946)

were cut open but soon after 21.00 h the Ottawa firemen were successful in controlling the spread of the deck fire.

17. The Hull Fire Department, on the other hand, had a much tougher fight on their hands since the pulpwood pile continued to burn for a couple of days. Shifts of watchers had to be used to check outbreaks caused by showers of sparks and burning embers. This threat persisted even though a large volume of water continued to be poured on the smouldering wood pile. The handling of traffic at this fire posed a major problem since thousands of citizens flocked to see the fire and to view the damage after the fire.

18. The fire severely damaged 780 lin. ft of highway and bridge deck and the supporting steel floor system, taking in nine of the trestle spans, the 140 ft and 247 ft truss spans, and part of the west anchor arm of the cantilever. The damage necessitated the removal and replacement of 37 000 sq. ft of highway floor and 780 lin. ft of railway ties and track. The railway portion was rehabilitated in 40 days. A patented steel grid filled with concrete was in- stalled to replace the previous wood and asphalt-plank construction of the flooring of the highway portion. Auxiliary services which were damaged were power lines and telephone cables. The pulpwood pile was an almost total loss and the associated conveyor systeill was destroyed. Careful and detailed studies were made of the effect of the fire on the steel in the spans directly a f f e ~ t e d . ~ Fortunately, no damage had been done; all spans continue in use today although they now carry vehicular traffic only, following a re- arrangement of rail tracks in the Ottawa area. The most probable cause of the fire was a glowing cigarette butt igniting the wooden decking.

Chats Falls Izy~Iro-electric plarzt

19. About

2&

million hp are generated by the fall of the Ottawa River and 47 1

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its tributaries. One of the first large water power plants on the river was constructed to take advantage of the drop in river level at the Chats Rapids, about 40 miles upstrean1 from the city of Ottawa. The Ottawa Valley Power Company and the Hydro-Electric Power Comnlission of Ontario, through a joint Chats Falls Executive Board, built the plant in 1931. The powerhouse is located with its central line on the boundary between Ontario and QuCbec. It is therefore some distance out from the Ontario (south) shore of the river and for~ns part of an earth dyke, concrete spillway and mass concrete retaining structure 12 100 ft in total length. The powerhouse contains eight generators developing 225 000 hp, originally at 25 cycles but they have now been rebuilt to generate power at 60 cycles. A frequency changer was added in 1935 to supply power at 60 cycles for trans~nission to the SE Ontario 60-cycle ~ y s t e m . ~

20. The main hall of the station is a space 558 x 50 x 57 ft high with galleries opening on to it at various levels. The floor of the main hall is at the 221 ft level. The gallery floors are at the 223, 236 and 252 ft levels. These open galleries, which are 20 ft wide, run the full length of the main hall. They are located between the upstrearn side wall of the powerhouse and the main hall. The galleries house auxiliary and service equipment, switch gear, battery rooms, a control room and offices. The building is steel framed (unprotected) with the frame carrying the rails for two large travelling cranes of 90 tons capacity. The walls are concrete, 12 in. thick, with the exception of the small 1935 extension, the walls of which are hollow clay block with cement plaster both on the interior and the exterior surfaces. The roof is a 4 in. concrete slab supported by open steel trusses. The gallery floors are constructed as reinforced concrete slabs. The north wall of the building had 27 windows 40 x 10 ft, reaching from 6 ft above the main floor to 12 ft below the roof. At the east end there was a 15 ft wide steel rolling door which was rolled up about

9

ft from the ground at the time of the fire.

21. Early on the morning of 2 March, 1953, four men were on duty at the station. Only three generators had been running overnight; No.

4

had been feeding into the main Ontario 25 cycle system and 2 and 3 had been directly connected to the frequency changer. At 06.00 h units

7

and 8 were put on load. Following the receipt of an instruction from the regional operator, generators 2 and 3 were taken off load. T o complete the operation it was necessary to open an oil-immersed disconnect switch located in the compound filled switch-gear on the middle gallery. Two attempts to operate the disconnect by remote control failed. The operators could not investigate the trouble immediately, having to put generators

4

and 5 on load at 06.50 h.

22. A short time later, at 06.53 h, the operator requested a third attempt to open the switch by remote control while he observed the mechanism. Suddenly it opened, accompanied by a blinding flash. Almost immediately the oil in the disconnect tank ignited. The fire very quickly reached the stage at which it could not be controlled by portable COz fire extinguishers. Gene- rators 2 and 3 and the frequency changer were immediately shut down. By this time, the west end of the powerhouse was full of black smoke and it was impossible to shut down generators

4-8.

The No.

9

generator had not been running. By 08.30 h, when a portion of the roof fell in, the smoke cleared sufficiently to allow all the generators except No. 2 to be stopped by closing the head gates, the brakes being released by hand. The head gates on No. 2 unit had jammed and several hours were required before water was finally

(24)

Courtesy : Fednews Fig. 3. Interior of the Chats Falls powerhouse after the fire of 2 March, 1953

shut off. At this stage the electrical hazard to the fire-fighters had been eliminated.

23. The station staff were reluctant to fight the fire with their portable forestry pumps in the early stages of the fire because of the electrical hazard. The very sudden spread of the fire was due to leakage of oil from the steel tank housing the disconnect switch, which presumably had been ruptured by the short circuit that gave rise to the blinding flash. In an effort to ensure safety, the original design had specified that all the station bus-bars be enclosed in metal ducts filled with insulating compound. Solid, and with a high flash point, the compound seemed to be a perfectly safe material to use in this way, but the heat of the burning oil from the disconnect tank melted it so that it ran out of the ducts and added to the flames. It also produced the large volumes of black smoke which quickly filled most of the upper parts of the main hall and cut off exit from the control room, the last operator fortunately escaping through an outside window. Governor oil which escaped from broken piping on the No. 2 unit and other combustible material (including oil) stored on the galleries also added to the intensity of the fire. Of an estimated 60 tons of combustible material apparently so safely stored, about 17 tons was consumed in the fire.

24.

Normal fire-fighting operations were handicapped by the isolated position of this powerhouse and the difficult terrain surrounding it. Access

(25)

to the powerhouse was by a mile of railway track which included three

bridges. It was not until 09.15 h that a fire pumper from the neighbouring

municipality reached the powerhouse, as planks had to be laid over the bridges

to enable the vehicle to traverse the railway track. Two 2% in. hose lines were

then laid and water played through window openings. By 10.45 h entry was

made into the building; the fire was brought under control by 12.00 h.

25. The fire severely damaged the powerhouse structure and electrical

equipment. About a third of the superstructure was seriously damaged. An

area of roof about 100 ft long and the full width of the building fell, dragging

with it the upper part of the wall on three sides. The collapse of the roof was

due to the failure of the exposed light steel members in the roof trusses, which

were badly twisted and warped. Part of the sagging roof slab lodged upon

the beam of the travelling crane 16 ft below roof level. Main steel columns

near the heart of the fire were twisted and distorted near their tops. Steel

beams between the main columns supporting the reinforced concrete floor of

the upper gallery and the roof over it failed by distortion and at their con-

nexions. The failure of these beams led to the collapse of the floor and of the

gallery roof. The frequency changer and generator No. 2 were severely

damaged but the seven other generators were not seriously damaged. The

auxiliary equipment on both galleries in the collapsed area was a total loss.

26. Total property loss was approximately $1 000 000. The portion of the

Ontario end of the plant associated with the frequency changer and No. 2

unit was out of service for eight months. The No. 2 unit, which had been

extensively damaged, was converted to 60 cycle operation and returned to

service in December 1954. Most fortunately, and despite the rapid develop-

ment and intensity of the fire, no lives were lost. Of all the fires known per-

sonally to the Authors, this was the most remarkable. The great powerhouse

interior was maintained in immaculate condition. Looking around one could

see 'nothing that could possibly burn.' And yet after the fire this same

building appeared as shown in Fig. 3.

Military warehorrse, Edmontorz

27. The Greisbach Barracks are located just outside the northern limits of

the City of Edmonton, Alberta, and cover a square mile of land. The main

warehouse building is 450

x

200 ft and was designed as three separate but

connected areas of 35 000, 30 000, and 25 000 sq. ft respectively, referred to as

areas A, B, and C. There were extensions of 40 and 42 ft at either end of the

building, giving a total area for the building in excess of 100 000 sq. ft. The

height from the top of the floor slab to the top of the roof slab was 24 ft.

28.

The structural frame of the building is of reinforced concrete. The

roof of the building is of precast concrete roof slabs covered with built-up

roofing and gravel. The exterior and interior walls are of 8 in. concrete blocks,

and the interior separation walls are 22 ft high and continuous for the entire

200 ft width of the building. The building is fully sprinklered and its equip-

ment included a fire alarm system; along the tops of the exterior walls there

are smoke exhaust windows 2 ft deep and continuous between columns.

29. In view of the size of the building and of the urgent need for storage

space, parts of the warehouse were put into service some months before the

completion of construction. Backfilling and grading around the building

were still in progress in November 1954; work was being carried out on water

(26)

F I R E

AND THE

C I V I L E N G I N E E R

Courtesy : Department of National Defence

Fig.

4.

Fighting the

1954

fire at the Greisbach Army Warehouse, Edmonton, show~ng

lack of access to building

mains in open trenches; roadways on the site were generally in poor condition.

On the morning of 11 November, 1954, a welder standing on a scaffold was

using a cutting torch to effect repairs to an anchorage of the main steamline in

Area C. Standing by him was a security guard with a soda-acid fire extingui-

sher.

A