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Economic design for fire safety
Lie, T. T.
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https://nrc-publications.canada.ca/eng/view/object/?id=f3ca3876-aabb-41e1-a9c9-16c23f879c76 https://publications-cnrc.canada.ca/fra/voir/objet/?id=f3ca3876-aabb-41e1-a9c9-16c23f879c76Economic Design for Fire Safety
by T. T. Lie
Division of Building Research, National Research C o u n c i l of Canada, O t t a w a (Canada)
A metlzod is disc~issecl by i.ol1ic11 the,fo-e loss expectation for b~tildings, botlz life loss and property loss, car7 be evaluated. T11e influence of various factors SLICII as building size and lleight, installation of sprinklers and ~letection systems, and,fire resistance o f the building are sAo,\l/i. Ail exan~ple is also given of how, in principle, optinl~n7ljre safety n~eas~ires can be determil~ed
Fire safety ~r~easures are regarded as optii?~um i f : (I) they provide at! adequate level of safety to people, here ass~inled to be eq~iiualent to a certain specijiecl loss expectation; (2) tlze swn of property loss expectatiot7 and expenrlit~lres for ,fire safety measures are ininimal.
There has been increased interest, in recent years, in optimising the cost of building fires.' This cost is composed of direct and indirect fire losses and expenditures to keep loss at a reasonable level. Property losses can, in principle, be optimised by balancing the expenditures for fire protection against the monetary benefit to be expected from a reduction of the probable fire loss. If lives are involved, however, tlie level of safety that corresponds to optimal property loss may not be sufficient and more protection may be needed to bring fire safety to an acceptable level.
One criterion for the degree of fire safety to be provided in a building is the fire loss expectation,
whicli can be defined as the probable loss, from fire, of human lives or property during the planned life of a building. A method lias been developed by which loss expectation, both life loss and property loss, can be ~ a l c u l a t e d . ~ T1ie use of loss expectation as a measure for the design of adequately safe and economically protected buildings will be discussed in detail. Loss expectation
During its life a building may be exposed to several extreme forces such as floor load concentrations, wind, earthquake, explosio~l or fire. If these forces are strong enough, all or a part of the building may collapse, with consequent loss of Copyright-Building Research Establishment, Department of the Envi~.onn~ent Build International (7) (19741-0 Applied Science Publishers Ltd, England, 1974-Printed in Great Britain
290 T. T. Lie
P R O B A B I L I T Y O F O C C U R R E N C E O F
O C C U R R E N C E O F L O S S E X P E C T A T I O N L O S S E S
Fig. 1 . The three rnaitz factors that deterinitre the fire loss expectatiott. life and property. Most losses in
buildings, both life and property, are generally caused by fire, with the possible exception of those caused by occasional catastrophic earthquakes in some areas. At present, asphyxiation and burns are the direct causes of life loss; structural failure has hitherto been
To assess the degree of safety provided it is necessary to be able to measure safety levels quantitatively. Such a quantity is the loss expecta- tion, which is determined by three main factors (see also Fig. 1):
(1) the probability of occurrence of a significant fire
a negligible threat. (2) the probability of occurrence In recent years, however, there of losses in the event of fire, has been a significant increase in the for example, owing to failure number of high-rise buildings. of safety measures
Owing to the increased length of
escape routes, people have more (3) the at risk and more been forced to remain for
considerable periods in buildings during fire emergencies. The possi- bility of fatalities from collapse of the building should therefore not be neglected. Such fatalities may increase substantially unless ap- propriate measures are taken to bring the fire safety of buildings to a n acceptable level.
These factors are, in turn, deter- mined by a large number of other , factors such as building size, value, occupancy, installation of sprinklers and detection systems, value of
.
contents, and amount and dis- position of combustible materials. Each factor can change one or more of the main factors, and this changeEconomic Design for Fire Safety 291 must necessarily affect the loss
expectation. The influence of various factors can be expressed quantitatively in a reduction of the loss expectation for any building condition, i.e. building size, value, occupancy, etc. If an acceptable level of loss expectation can be specified, the measures that provide this level of safety can be chosen and the most economical measures determined by comparing costs. If only property losses are involved, which is often the case for conventional buildings as opposed to high-rise buildings, the total cost of fire can be opti- mised by balancing the cost of protection against the reduction of the loss expectation.
Influence of various factors on loss expectation
An expression has been established for loss expectation as a function of significant parameter^.^ With it the influence of a large number of parameters can be examined in detail. For example, loss expectation for structural failure caused by fire will be considered; loss expectation for other extreme forces can, in principle, be developed in a similar manner. The most important factors that determine expectation of loss caused by structural failure are shown in Fig. 2. The evaluation of loss expectation is rather elaborate and, although not entirely correct, it will be assumed that loss expectation
P, - P R O B A B I L I T Y O F O C C U R R E N C E O F S I G N I F I C A N T F I R E 1 B U I L D I N G S I Z E A N D H E I G H T 2 M A T E R I A L S I C O N T R l B U T l O N TO F I R E G R O W T H ) 3 D E T E C T I O N
h
4 S U P P R E S S I O N I S P R I N K L E R S . E X T I N G U I S H E R S , E T C )I
1 F l R E R E S I S T A N C E 2 F l R E L O A D 3 V A R I A B I L I T Y O F F I R E R E S I S T A N C E L O S S E X P E C T A T I O N 1 B U I L D I N G S I Z E A N D H E I G H T 2 O C C U P A N T L O A D 3 M E A N S OF E G R E S S 4 V A L U E O F B U I L D I N G 5 V A L U E O F C O N T E N T S 6 C O N S E Q U E N T I A L L O S S E SFig. 2. Factors that determine the expectation oj losses d~rri~zgfie dire to strnctioal faihrre.
292 T. T. Lie is formed by the product of the three
main factors p , , p,. and u, where
p , = probability of occurrence of significant fire
p,. = probability of occurrence of structural failure
u = value at risk
It may be seen in Fig. 2 that use of materials with a low contribution to fire growth, detection systems and sprinklers reduce the probability of occurrence of a significant fire. If, for example, sprinklers reduce the number of significant fires by a factor of three, then loss expectation will also be reduced by a factor of three.
I n the event of a significant fire, structural members will be exposed to severe heating and may fail as a consequence. It depends o n the fire resistance of the members and the fire load in the burning compartment whether failure will occur. If, by chance, the fire load is so high and the fire resistance so low that it is insufficient to resist the strength- reducing effects of prolonged ex- posure to fire, structural members will probably fail and the building collapse. By increasing the fire resistance, however, the probability of failure can be reduced.
Probability of structural failure depends also on the variability of fire load and fire resistance. Fire load can vary in a wide range, especially where there are fire load
concentrations such as storage areas. These areas may significantly increase the probability of structural failure because they can prolong the duration of the fire.
The variability of fire resistance is a further factor in determining the probability offailure. Fire resistance depends to a certain extent on the accuracy of design and construc- tion, which is greatly affected by accuracy of analysis, knowledge of material properties, and quality of workmanship. T h e quality and nature of the materials used are also important in determining fire resistance.
I t may be expected that fire resis- tance will vary widely with the type of structure and the materials used in its construction. Steel structural members protected with light insula- ting materials that d o n o t deterior- ate a t high temperatures (for example, mineral wool, vern~iculite a n d perlite boards) have a relatively low variability of fire resistance. I n addition, the parameters that deter- mine the temperatures in protected steel members are known so that it is possible to predictthe temperature rise in the steel with reasonable accuracy. This contributes to reliability in obtaining the con- templated fire resistances.
Structural members with a rela- tively high variability of fire resist- ance include those of prestressed concrete.3 The fire resistance of
Economic Design for Fire Safety reinforced concrete members, 011 the other hand, is reasonably reliable. Even if spalling takes place the reduction in fire resistance is rarely serious provided the thickness of the cover protecting the steel is less than about 3 cm or wire mesh is placed in thicker protection.
As a rule the lower the variability of fire load and fire resistance, the lower the probability of structural failure. Prevention of fire load concentrations, use of chemically stable insulating materials and in- spection of workmanship can con- tribute substantially to reducing the probability of structural failure.
If a fire occurs and there is structural failure, losses may be con- siderable. Their seriousness will depend on the value a t risk. If no lives are involved and the value of property is low, the loss expectation will usually be low. This is often the case for traditional buildings of rather limited size. I n such cases no fire safety measures are necessary except the provision of a minimum fire resistance t o prevent collapse of the building during the period of evacuation. On the other hand, if the value at risk is high, for example owing to high value of contents or many lives involved, appropriate measures should be taken to bring the loss expectation to a n acceptable level. In general, this can beachieved by measures that reduce the prob- ability of occurrence of fire or the
probability of structural failure, o r both.
One of the most influential factors determining loss expectation is the size and height of the building. It may be seen in Fig. 2 that both these factors affect the probability of occurrence of a significant fire a s well a s the value at risk. In general, the probability of occurrence of fire in a two-storey building is twice that in a single-storey building if the storeys are of the same size, equally equipped, and used in the same way. Under the same conditions, build- ings of a greater number of storeys of equal size have probabilities of occurrence of fire proportional t o the number of storeys. In addition, the value of the building and contents as well as the number of occupants, which together form the value a t risk, are also proportional to the number of storeys. Thus, both probability of occurrence of fire (p,) and value a t risk (u) are proportional to the height of the building. As a result, there will be quadratic increase in loss expecta- tion, which is proportional to the product p, x u, with height of building unless additional measures are taken to reduce it.
Acceptable safety level
The most common measures for reducing loss expectation are a t present provision of sprinklers and detection devices, use of low hazard
T. T. Lie
materials, and confinement of fire to the compartment in which it starts by means of fire resisting construc- tion. Each of these measures can be taken individually or in combina- tion. Which should be chosen depends on the level of safety desired, the known effectiveness of each measure, and the cost.
In general, protection of the lives of occupants of buildings is of primary importance. I t is clear that the more protection provided the safer the building. It is not possible, however, to make buildings perfectly safe, and a certain low probability of occurrence of life loss has t o be accepted. T o determine how much protection is to be provided an acceptable level of safety must be specified. One method of determin- ing such a level is by comparing the risk of death by fire with the risk involved in other activities such as bus or rail travel, swimming, smoking, etc. Values of risk for various activities can be found in the literature. 4 - 5 According to these data the risk people run when they travel 100 times a year by bus or rail is approximately one death in l o 5 per year. The risk of walking near roads is about five in l o 5 per year, the risk of climbing stairs about the same, the risk of auto- mobile travel roughly three in lo4 per year, and that of smoking one in
l o 3 per year.
The risk of fire is a t present about
three in 10' per year in Canada. It may be seen that this risk is in the same order of magnitude as the risk of travel by bus or train, the risk of walking near roads, or the risk of climbing stairs. These activities are practised daily by many people without much thought of safety. In this light the present Canadian fire risk of three in l o 5 per year might be considered as a n upper limit in relation t o fire safety requirements. The expected effect of fire safety measures based on this value of life loss expectation is t h a t average future life losses will be a t least not higher than present average fire losses.
Optimisation of safety measures Fire safety measures are optimum if:
(1) they provide an adequate level of safety to people, here assumed to be equivalent to a certain specified loss expecta- tion;
(2) the sum of property loss expectation and expenditures for safety measures are minimal.
How, in principle, optimum measures can be determined will be discussed in the example below. Although many more measures can be taken t o reduce fire loss expecta- tion, only the most common will be considered, i.e., provision of sprinklers and detection systems,
Economic Design for Fire Safety 295 use of low hazard materials, and
confinement of fire in fire-resisting compartments. Each of these measures will, to a certain extent, reduce loss expectation. At present, however, data on the influence of sprinklers, detection systems, and use of low-hazard materials are still meagre and some values for the parameters6 that determine loss expectation are known only roughly. In this example values have been assumed or estimated for param- eters for which information is insufficient.
Calculations to determine loss expectation and optimum measures
have made use of formulae de- scribed in Reference 2. I t is assumed that each storey of the building under consideration has a n un- divided floor area of 2000 m Z a n d that each storey is a fire-resistant compartment. Subdivision of each storey into fire-resisting compart- ments may have a significant effect on loss expectation a n d optimum measures. This case h a s not been studied so far a n d will therefore n o t be discussed. The values of the parameters used in t h e calculations and all other important information are given in Table I . A s many values can vary widely, the results should Table 1 Parameter Vallres Asslrmed,for the Present Calc~rlations*
Floor area of one storey: Service life of building:
Loss of contents and indirect losses: Cost of repair:
Interest rate:
Coefficient of variation of fire load: Coefficient of variation of fire resistance: Probability of occurrence of significant fire:
No sprinklers, detection or use of low fire hazard materials :
Sprinklered :
Sprinklered
+
detection and use of low fire hazard materials:Cost of sprinklers:
Cost of detection and low fire hazard ~naterials: Cost of fire resistance:
Cost of building
2000 111 2
50 years
3 times building cost
5 times building cost 7 0/, per year 0.7
0.4
0.2 x 10- 6 per m2 per year 0.667 x 10- 7 per in2 per year
0.2 x 10-7 per n12 per year 2 % of building cost 2 % of building cost
0.5% of building cost per unit increase of design factor $500 per n12 floor area * These values must be regarded as hypothetical, although an attempt has been made to ensure that they are reasonably representative within the limitations of the available data.
T. T. Lie not be given general application.
Tliey apply only to conditions that more or less resemble tlie conditions assumed in the calculations. A more detailed discussion of the influence of significant parameters in various ranges, as well as calcula- tion procedures, will be given in another paper.
Low buildings
In Fig. 3 the total cost of fire, including loss expectation and ex- penditures for safety measures, is plotted for 2-storey and 5-storey buildings as a function of the fire load design factor. This factor may be considered a safety factor for fire resistance; it is equal to the ratio of the fire load on which the fire resistance design of the building should be based to the mean of the fire load to be expected in the building. The mean fire load can be determined from analysis of actual fire loads in representative buildings. I n general, the higher the fire load design factor, the higher tlie fire resistance of the building.
For lower buildings it may be assumed that structural failure will not cause life loss; that losses will be property losses. Provision o f fire resistance for these buildings, there- fore, is often not beneficial. Figure 3 illustrates the fact that for a 2-storey building (curves 1 , 2 and 3) provision of fire resistance will increase the total fire cost. This cost
1s nlinin~uni when the building is sprinklered (curve l), but the differences in total cost for the various measures are t o o slnall to make them conclusive. I n practice, a certain minimum fire resistance must be provided to allow for evacuation, even if it is not econ- omically justified.
The differences in total cost of sprinklered and unsprinklered 5- storey buildings are more pro- nounced (curves 4, 5 a n d 6). The total fire cost is minimal when the building is sprinklered and fire resistance corresponding to a design factor of about 2 is provided. For modern oflice buildings this means a fire resistance in the order of $ to
1 hour.
High buildings
In higher buildings, for example, 10 storeys and more, there is a con- siderable chance that people will have t o remain in the building until the fire has burned out; evacuation time may be very long o r parts of tlie building may be beyond the reach of the aerial equiplnelit of tlie fire brigade. Studies have sliown that the time necessary for evacua- tion is approximately proportional
.
to the height of the building and to the occupant s o that it can vary froni a few m i n ~ ~ t e s to several ahours. This implies that in the evelit of s t r u c t ~ ~ r a l failure both the prob- ability that people will be present
298 T. T. Lie and the number of people involved the life loss expectation, to a n increase with building height and acceptable level.
occupant load. Thus, in high How life loss expectation is buildings structural failure may affected by various measures is cause substantial life loss and shown in Fig. 4 for a hypothetical measures should be taken t o bring case in a 25-storey building. The life the fire safety of the building, i.e. loss expectation depends strongly o n
1 F I R E R E S I S T A N C E O N L Y 2 F l R E R E S I S T A N C E + S P R I N K L E R S - 3 F l R E R E S I S T A N C E + S P R I N K L E R S + D E T E C T I O N A N D U S E O F L O W H A Z A R D M A T E R I A L S - - 2 4 6 8 1 0 12 1 4 1 6 18 F l R E L O A D D E S I G N F A C T O R ( R A T I O D E S I G N F l R E L O A D T O M E A N F l R E L O A D )
Fig. 4. It~flrretzce of vnriorrs measlrres otz the life loss expectation f o r u 25-.storq~ buildirig.
Economic Design for Fire Safety 299 the assumptions made regarding the safety levels, A and B, are shown. number of people expected to be It may be seen that safety level A present in the event of structural can be obtained by providing (only collapse. Factors that determine measures specified earlier are taken this number are occupant load, size into consideration):
of building, and extent to which means of egress has been provided. At present, data are still insufficient to permit reliable assumptions re- garding this number. F o r the purpose of illustrating how, in principle, optimum measures can be determined, therefore, only rela- tive numbers are given for loss expectation.
It may be seen in Fig. 4 that increasing the design factor o r fire resistance initially reduces loss ex- pectation greatly. At higher design factor values, however, provision of more fire resistance has little effect on loss expectation; in fact, a relatively greater reduction in loss expectation can be obtained by providing sprinklers, detection de- vices, and low-hazard materials. The differences in the curves, however, will be dependent upon the basis for determining the number of people a t risk in the event of structural collapse.
Selection of measures
The measures or combination of
I measures that should be chosen
depends on their effectiveness, on
1
the level of safety desired, and on cost. How the safety level affects
I
, them is illustrated in Fig. 4 ; two
I fire resistance corresponding to a design factor of 7 ; I1 fire resistance corresponding
t o a design factor of 3.7
+
sprinklers ;111 fire resistance corresponding to a design factor of 2.1
+
sprinklers+
detection and use of low hazard materials. T o obtain the higher safety level B only two methods can be used :IV fire resistance corresponding t o a design factor of 8
+
sprinklers;V fire resistance corresponding to a design factor of 3.6
+
sprinklers+
detection and use of low hazard materials. l n this case the desired safety level B cannot be obtained by provision of fire resistance only. I t is obvious that the higher the level of safety desired, the more extensive the measures required to provide it. A s a consequence, cost will increase with the level of safety. Of course, useful expenditures are not un- limited. There is a certain n ~ a x i n ~ u m that can be expended and this implies that a certain reasonable level of safety has to be accepted.300 T. T. Lie C S = C O S T O F S P R I N K L E R S : I";. - C D C O S T O F D E T E C T I O N A N D I FlRE USE O F L O W H A Z A R D R E S I S T A N C E - - M A T E R I A L S : I": - - l o I - - II FlRE R E S I S T A N C E . - S P R I N K L E R S -
-
- R E S I S T A N C E . S P R I N K L E R S - - D E T E C T I O N A N D USE O F LOV! H A Z A R D - M A T E R I A L S I I - C O S T O F S P R I N I LERS 2 I FIRE-
C D C O S T O F D E T E C T I O N A N D R E S I S T A N C E - USE O F L O \ ' H A l A R D O N L Y - M A T E R I A L S 2 - - 1 1 I l l F l R L - P E S I S T A N C E - S P R l N h L E R S - - R E S I S T A N C E - S P R l N hLERS - D E T E C T I O N A N D USE O F L O \ ) - I - I A Z A R D h \ A T E R I A L S - C F = C O S T O t FlRE R E S I S T A N C E PER U N I T I N C R E A S E O F D E S I G N F A C T O R , "- I )Fig. 5 . Cost o f mensrrres to provide snfety level A (011 cost^ Or perce~~tnge of' b~rildi~rg cost).
Economic Design for Fire Safety is specified, it will be possible to determine which measures provide this degree of safety; and if the cost of the measures is known, it will also be possible to determine which are optimum, i.e. which are most economical. How cost affects opti- mum measures is shown in Figs. 5 and 6 ; the total cost is plotted as a function of cost of providing fire resistance. The cost of fire resistance (C,) is based on a unit increase of the fire load design factor (all costs are expressed in percentages of building cost).
In Fig. 5(a) it is assumed that safety level A (Fig. 4) is provided and that both the cost of sprinklers (C,) and that of detection and use of low hazard materials (C,) are 1
%
of building cost. As specified, there are three means by which safety level A can be obtained, i.e. methods I, 12 and 111. The cost of each is shown in Fig. 5(ci). It may be seen that up to a fire resistance cost, C,, of 0.3 %,, method I is tlie optimuni choice. For C, between 0.3 and 0.7tlie o p t i n ~ ~ ~ i n choice is method 11, and for C, greater than 0.7 it is method 111.
Figure 5(b) shows optirnum measures if costs C, and C, are 2
:I
each, instead of 1
%.
I11 this casesubstantially higher costs of fire resistance are justified before they become ~ineconoinical.
If instead of safety level A the higlier safety level B is desired,
provisioii of fire resistance only is not sufficient. T o obtain safety level B, provision offire resistance should be combined with other measures, as specified previously ~iiider methods I V and V (see also Fig. 6). It is possible to providea highdegree of safety, but higher costs are in- herent in the higher degree of safety. Figure 7 shows total fire cost corresponding to optimal measures for buildings of various heights. I n higher buildings most of the cost is for provision of a n adequate level of safety for occupants; and these expenditures increase progressively with height of building. For lower buildings, optimal expenditures are relatively lower because no life losses due to structural failure are expected. Under the assumed con- ditions, optimal expeildit~~res are approximately 2 '%, for a 2-storey building, 3 %for a 5-storey building, 5.5
:';
for a 10-storey building, 6.5 '%, for a 30-storey building, and 8.5:';
for a 50-storey building.Conclusion
This study has considered tile influence of only a few parameters t o illustrate how, in principle, optimum fire safety measures can be determined. I t is possible, how- ever, to calculate for any specific situation the measures that are optimal. Although the calculation procedure is rather complex and elaborate it is relatively easy to
302 T. T. Lie IV F l R E - C S = C O S T O F S P R I N K L E R S : 1 % T R E S I S T A N C E S P R I N K L E R S - = C O S T O F D E T E C T I O N A N D U S E O F L O W H A Z A R D - M A T E R I A L S : 1 9 0
-
- V F l R E - R E S I S T A N C E +-
S P R I N K L E R S - + D E T E C T I O N A N D U S E O F L O W H A Z A R D - M A T E R I A L S --
- C s = C O S T O F S P R I N K L E R S : 2 ' 0 IV FIRE - CD = C O S T O F D E T E C T I O N A N D R E S I S T A N C E - - USE O F L O W H A Z A R D S P R I N K L E R S - M A T E R I A L S : Z o o - --
( b ) V F I R E - R E S I S T A N C E - S P R I N K L E R S --
- D E T E C T I O N A N D U S E O F - L O W H A Z A R D - M A T E R I A L S - - - C F = C O S T O F F l R E R E S I S T A N C E PER U N I T I N C R E A S E O F D E S I G N F A C T O R , 46 4Fig. 6. Cost of'measrlres to provide sajety level B (ull costs itr percetrtuge o f
S T O R E Y S
I
Fig. 7. Optimum f i e cost per bltildit~g as n jirt~ctiotr of Drrildt7g height.
programme and with a compi~ter References
solutions can be obtained for 1. ASCE-IABSE International Con-
numeroits situations with accilracy
g i r ~ ~
~~~i7~32,~:!&$22~
and speed. of Civil Engineers, New York, 1972.2. LIE,T. T.,Optirnuni Fire Resistance of Structures, Journal of the Structural Division, Proceedings of the American Society of Civil Engineers, 98, No. STI, 1972, pp. 2 15-232.
3. Brandproeven op Voorgespannen Betonliggers, C.U.R. Rapport No. 13, Commissie voor Uitvoering van Research, Betonvereniging,
Holland, 1958.
4. PUGSLEY, A., The Sufity oj'
S t r l ~ c t l ~ r e s , Edward Arnold Ltd., London, 1966, pp. 81-96.
5. ALLEN, D. E., Discussion of 'Choice of Failure Probabilities' by C. J. Turkstra, Journal of the Structural Division, A~iierican Society of Civil Engineers, No. ST9,
1968, pp. 2169-2173.
6. LIE, T. T., Fire a ~ i d B l ~ i l d i ~ l g s , Applied Science Publishers Ltd., London, 1972, pp. 21 1-231. 7. GALBREATH, M., Time of
Evacuation by Stairs in High Buildings, Fire Research Note. No. 8, National Research Council of Canada, Division of Building Re- search, 1969.
8. WILSON, A. G., SHORTER, G.
W., Fire and High Buildings, Fire
Techt~ology, 6, (4) 1970, pp. 292- 304.
T. T. Lie
This paper is a contributioll fro111 the Division of Building Research, National Research Council of C a n a d a , and is published with the approval of the Director of the Division.
T . T. L i e is a reserrrch oficer w i t h the F i r e Section, Dioisio~z of B~1ilrli17g Research, National Research Council of Canacla, and a g r a t l ~ ~ n t e in. Engi~ieeritig Pliysics of the Technical Utzi~jersity of Delft. H e worker1 in the .fie/(/ of,fire in the Organisatioti .for
Appliecl Scietitific Research, T. N. O . , in Hollat7cl ,j+on? 1954 t o 1967 m7d st~~cliecl on a ,fello~vship nt the B~tilcling Researcli l t i s t i t ~ ~ t e it7 Jupatz rlrtritig 1 963. H i s curretit resenrch
it7clucles st~~clies it1 the , f i e / /
01'
s t r u c t u r n l ,fire protcctioti C ~ I I ~ proba-
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