•

ment has been pressurised for structural purposes might be prepared on an multi- intuitive basis as shown in Fig. 3. Access to this is gained by means of an airlock at ground air-supported level. The necessity of changing from one pressure to another on leaving or building entering a pneumatic building will present problems to the , hitherto not considered in connection with building construction. Basically, the lock can be described as an airtight by J. G. Pohl and H. J. Cowan chamber fitted with a door at each end, UDC 69.033 both doors opening toward the pressure. Through valves at each end, the pressure within the lock may be equalised with Recent~y, over a three-year period, a new concept of multi-storey that of the building or with the external building construction based on pneumatic principles was investigated atmosphere. When the pressure in the in the Department of Architectural at the University of airlock is the same as that of the pres­ surised zone, the inner door may be Sydney, . The results of this research, which formed the basis l opened to allow persons and material of a doctorate thesis and various technical publications,2,3,4 have to enter the lock from this zone. The indicated that multi-storey supported by internal air­ inner door is then closed and the pressure and surrounded by a thin, fleXible or rigid membrane acting pressure within the lock reduced to both as structural container and external cladding, are feasible and atmospheric conditions allowing the highly economical for a number of building applications. This article outer door to be opened to complete by Jens G. Pohl, Faculty of . University of New South the exit operation. Both doors of an Wales, Kensington, and Henry J. Cowan, Department of Architec­ airlock can never be opened at the same tural Science. University of Sydney, Sydney, describes those elements time, because when either of the doors is of the thesis which are useful for practitioners. closed it is held tightly against a gasket by air pressure. Although the development of this type of airlock in tunnelling operations has been based on a considerable amount of practical experience, existing will need to be very much refined and automated before they can be in­ The simplest form of multi-storey air­ primary of a large building corporated in the of multi-storey, supported building is best described carries with it a number of significant pneumatic buildings. While rates of de­ as a flexible tube sealed at both problems related to the physiological compression will be fast and therefore ends by means of circular discs and effects of an hyperbaric environment, little time will be spent in airlocks by pressurised internally as shown in maintenance of the design pressure, persons entering or leaving the building, Fig. 1. Similar to a pressure vessel, fire protection, mechanical equipment, the visual airlock environment must not the resulting column experiences tensile structural pressure-utilisation efficiency differ in principle from the interior stresses over its entire curved surface. of the system and the disposal of wastes. building environment. If the internal pressure is continuously At the same time, it is apparent that It is likely that at the present time increased and the sealing discs are the multi-storey, pneumatic building people would reject the mechanical sufficiently stiff to resist dishing, even­ described here in its simplest form as a tually the column wall will burst as a single-skin structure immediately sug­ result of material failure in tension. gests a number of related building types Naturally, in its inflated state the mem­ of a double-skin or cellular nature brane column is capable of supporting which would, no doubt, lead to a re­ vertically loads applied externally to the duction in the complexity of most of upper end or suspended from the same these problems. internally. The transition, therefore, However, before investigations could from the simple model shown in Fig. be undertaken in this direction, it was I to a multi-storey, air-supported decided to come to terms with the building with suspended (Fig. difficulties inherent in the practical 2) is direct and rather obvious. It implementation of the multi-storey, appears that existing such as single-skin, pneumatic system which, gasometers, hydraulic car hoists and from a purely structural point of view, Figure I Inflated fleXible, plastic mem­ rocket fuselages incorporate similar would appear to hold most potential. brane tube as a stable column (membrane principles. Nevertheless, the employ­ Accordingly, the design of a lo-storey thickness 0·002 in; internal pressure of ment of a pneumatic container as the building, in which the environ­ 1·0 psig (approximately); diameter 3 in)

110 BUILD International, March/April1972 •

appearance of an airlock system de­ the simplest solution. In this case, the signed purely on the basis of functional function of the water is preserved criteria. Therefore, it will be necessary and the waste will reach the sewer after at least during the early stages of the passing through one or more stages of development of multi-storey, pneumatic decompression. This procedure can be buildings, to disguise some of the out­ further improved by combining a num­ standing mechanical characteristics, al­ ber of similar waste pipes at a central though this must not be to the detri­ decompression unit. It seems highly ment of the safe operation of the pneu­ probable that these waste pipes would matic system of construction. It is require artificial ventilation at the same reasonable to assume that the rate of pressure and therefore in conjunction pressurisation will be slightly less than with the central air-conditioning system. the time required for an adult person to It is unlikely that an hyperbaric walk at a comfortable pace the distance building environment will significantly between airlock doors. Having entered modify water supply, apart from the the ground floor , access to other necessity of providing pumps of slightly floors is provided in the normal manner, greater capacity (i.e. in proportion to namely, via lifts and staircases. the environmental pressure) than in an orthodox building. The rate at which the water must be boosted will no doubt exceed the limit of draw permitted by the water authorities; however, a break tank system is not necessarily required. Although water authorities are willing to accept a considerable drop in the mains pressure for emergency situa­ tions, near negative pressures cannot be tolerated. Therefore, even purely from the point of view of fire services, the multi-storey, pneumatic building will

require considerable tank storage. In FLOOR pLAN this case there is unlikely to be an alternative to low-level storage, the actual amount being determined by agreement with the fire-fighting and water authorities.

Since there is a need for storage at low ,."EUURIZEO level, it will be worthwhile to make it adequate and reduce that at high level o 10 20FT AIRLOCK ENTRANCE in the building, thereby reducing the ~ load to be carried by the internal Figure 3 Typical multi-storey pressur­ pressure of the building. As shown in ised membrane-cable-network building Figure 2 Working model of multi­ Fig. 3 considerable space has been storey, membrane-cabIe-network building allocated at level for mecha­ incorporating a suspended floor system nical plant including air-conditioning, pressurisation, airlock and lift equip­ Each suspended floor level is planned ment, and it seems plausible that water to incorporate a centralised storage tanks could likewise be located space; comprising all sanitary require­ at this level. ments. ducts, fire-escape staircase and For reasons of maintenance and storage facilities; vertical general accessibility, it would appear to systems and a series of sliding screens at be logical that the plant area should the perimeter for the purpose of pro­ operate at ambient atmospheric condi­ viding acoustical and visual privacy. tions. Since it is intended for the entire floor­ Structural considerations to-floor volume to be pressurised, The application of pressurised, mem­ sanitary and dry waste disposal in­ brane columns to multi-storey building stallations will need to receive special construction will require a convincing attention. Under present conditions, no knowledge of the failure mechanism authority could tolerate the discharge of under both vertical and horizontal loads excremental matter into a public and the pressure-utilisation ability sewerage system at pressures con­ under vertical load alone. Both of these siderably above atmospheric pressure. are naturally dependent on the slender­ Figure 4 Rigid. membrane column The provision of airlock mechanisms ness ratio of the column and the ratio (membrane thickness 0·01 in; diameter within waste pipes would appear to be of load to internal pressure. 9·5 in)

BUILD International, March/April1972 111

--~ =

multi-storey air-supported 8 LB building construction

f----WALL TH ICKNESS 't'IN--'-/

While rigid membrane columns (Fig. 4) will normally retain their shape under self-weight loading conditions even in the absence of internal pressure, Figure 5 Short, pressurised. membrane column action the flexible membrane column (Fig. 1) depends upon fluid pressure for its shape and resistance to bending, local buckling and torsion. For short columns this resistance has been found to be a function of the internal pressure, mem­ brane thickness and elasticity of material. 4 Under vertical load (Fig. 5) first stage failure of a flexible membrane column will occur at the instant when the tensile stress due to internal pressure is negated by the dual action of axial compression and deflection moment, on one side of the column perimeter (Fig. 6). Accordingly, the column will become unstable, not when there is an unequal stress distribution in the mem­ brane wall, but as soon as any section of the membrane experiences no stress at. all in the vertical direction. After the formation of folds the load­ bearing capacity of the membrane column decreases rapidly (Fig. 7) since any increase in displacement will Figure 6 First stagefailure ofajlexible, Figure 7 After the formation of folds produce a larger lever arm and conse­ membrane column. Note the formation of the load-bearing capacity ofthe membrane quently a greater bending moment. folds on one side of the column column decreases rapidly When pressurised, flexible membrane columns are displaced by a horizontal force acting at the free end (Fig. 8) the fibres on one side of the column are stretched, while again on the opposite L pSI side a corresponding unloading action takes place. Folds can occur only after the tensile stress due to the internal pressure can no longer absorb the com­ pressive stresses induced by the hori­ zontal force. It is therefore clear that the load-bearing capacity of short membrane columns is largely deter­ mined by the internal pressure. The question then arises, what proportion of this pressure acting on the inside face of the upper seal can be directly utilised for the support of a vertical load? Theoretical predictions followed by experimental investigation1. 4 have / shown that the approximate pressure­ utilisation factors (k) given in Table Figure 8 Bending mechanism offlexible, membrane column under horizontal load

112 BUILD International, MarcbfApril1971 ri •

Table 1 Pressure-utilisation factor (k) as a function of the slenderness ratio of multi-storey, single-skin, pneumatic build­ ings (i.e. load-bearing capacity (W lb) = kPA; where 'P psig' = internal pressure 'A in 2' = area ofinside surface ofupper­ end seal).

Pressure- Slenderness Height utilisation t ratio diameter factor 15 2-6 k = 0·85 1 20 3'5 k = 0·80 25 4'4 k = 0·75 30 5-3 k = 0·70

I hold within the normal range of 2­ to 12-storey buildings. These factors can now be calculated precisely on the basis of design equa­ tions published elsewhere. 4 If it can be o SFT reasonably assumed that the normal I." d I floor load (i.e. dead and live load) con­ Figure 9 Three-storey, experimental, membrane building with exterior cable-network sidered in the design of high-rise build­ for reinforcement and bracing purposes ings is in the vicinity of 140 pounds per foot (psf), then an internal pressure of close to 1 pound per square to internal pressure by means of an A long history of experimental in­ inch (psi) of 144 psf, above ambient external cable-network (Fig. 9) while vestigations and experience with cais­ atmospheric pressure will be required the membrane serves simply as a non­ sons must assure us that the appearance for the support of each floor of a multi­ porous envelope. Under these circum­ of any long-range effects, such as com­ storey structure. This is so, because the stances the required tensile strength of pressed air illness, bends syndrome and area of a typical floor, as shown in Fig. 3, the membrane material will be sub­ oxygen-poisoning, can be generally dis­ cannot be greater than the area of the stantially lowered, allowing the use of a counted if the ratio of environmental to inside surface of the upper seal (i.e. the much wider range of plastic materials. external atmospheric pressure is small. 2 bearing floor). For example, the required As shown in Fig. 9 cables are inclined According to DeweY,5 symptom­ internal pressure for a typical eight­ at an optimum angle, symmetrically producing nitrogen bubble formation in storey, pneumatic, membrane building about the vertical axis to fulfil the the blood stream will not occur unless a of 50 ft diameter and 100 ft height can further function of stabilising the build­ threshold-pressure-gradient of 2: 1 is be calculated to be 8'85 psig, with a ing laterally against the action of exceeded. This means that if the corresponding pressure-utilisation factor wind loads. 4 For the ensuing membrane­ building environment is pressurised to (k) of 0·90. cable-network building, design equations less than two atmospheres absolute Similarly, the tensile hoop stress of are adapted to transfer the primary (i.e. approximately 14 psig) long-range the membrane enclosure in this example structural function from the membrane physiological effects are not likely to would be approximately 2700 lb/in. to the cable-network. occur even if this change of pressure is Assuming the membrane thickness to be produced instantaneously. Furthermore, 0'13 in, the yield strength of the material The hyperbaric building environment since the rates of compression and de­ would need to be around 25,000 psi, Although it might have been established compression are the primary variables with a corresponding ultimate strength previously as a rule of thumb that for which determine the occurrence of de­ of some 40,000 psi. Where high tensile every 1 psig internal pressure it will be compression sickness, it would appear strength is the primary criterion, a possible to support one floor of a multi­ that higher environmental pressures and suitable membrane material is likely to storey, pneumatic building, the question therefore taller buildings are feasible, be found among the laminates and rein­ of what effect this compressed air en­ provided the rate of change from one forced . However, a survey of vironment will have on the building's pressure to the other is sufficiently slow. commercially available materials has occupants remains to be considered. Nevertheless, present research has been shown that it is difficult and costly to From a structural point ofview (Table 1) limited to pneumatic, membrane build­ manufacture plastic membranes to this it appears that a height to diameter ings involving pressures below 14 psig, specification. At this time, nylon scrim­ ratio of 3: 5 with a pressure-utilisation with a maximum of ten to twelve based laminates capable of developing a factor (k) of 0·80 might be reasonably storeys. yield strength of more than 10001b/in considered to approach an economic seem to be most suitable for this appli­ limit. Nevertheless, it would be Pressure maintenance and safety cation, even though they are well below expected that the physiological effects on General safety considerations for multi­ the strength requirement. For most man living in a compressed air en­ storey air-supported buildings can be membrane buildings it will therefore be vironment will constitute the more considered from three principal aspects; advisable to resist the hoop stress due critical design criterion. firstly, the establishment of factors of

BUILD International, March/April 1972 113 •

multi-storey BEARI NG FLOOR air-supported r t 11 i FIXED .­ I ~ MEMBRANE AND building construction DIAGONAL TENSION ...--­NET

~-- COMP RESSION WALL OR T ENS ION CELLS f­ '-..... --::--I>-FLOORS SUSPENDED FROM ...... ­ BEAR ING FLOOR

I-­ BUIl-DI NG ENVIRONMENT -- llill PRESSURIZ ED -PRESSURIZ ED ANNULUS safety compatible with risks undertaken ...... ~--

by persons elsewhere and the kind of V ERTI CAL TRANSPORT mechanical building under considera­ I­ - SHAF T tion; secondly, the ability of the mem­ brane enclosure to localise punctures --- which might occur during the life-span 1­ of the building; and thirdly, the ENTRANCE ' .. - adequate performance of the pressurisa­ ' ...... : . ' . ..:...... tion plant during an emergency situa­ ...... , tion. _ !-.---SE !-lVI CE PLANT Multi-storey, pneumatic buildings are . basically mechanical buildings and it is therefore unlikely that factors of safety required by existing building codes SUSPENSION FLEXIBLE MEMBRANE should apply. It would seem that at the CA BLES present time their application might be OMPRESSION CYLINDER OR TENSION CE L LS considered primarily for providing im­ mediate shelter in disaster areas or wherever low cost, speed of erection and mobility are the foremost design SERVICES AND FIRE ESCAPE criteria. With the rapid increase in world population, there seems little doubt that such conditions will pre­ PR ESSURIZ ED M~NULUS occupy the building in the twenty-first century. Faced with a critical situation authorities will be forced to align factors of safety in building construction with normal risks o 10 20FT undertaken in everyday life. I" "I I Is it reasonable to prescribe a factor Figure 10 Cellular, membrane-cable-network building with suspended floor system and of safety for a building, which would internal environment at ambient atmospheric pressure make failure less likely than the pro­ bability that a person might be hit by a golf ball as he is walking down the street and die as a result of this accident? single-skin, multi-storey, pneumatic Similar precautions are taken in hos­ Surely the time will come when we will building, puncture of the membrane pitals to ensure a continuous electricity have to provide buildings in such large naturally constitutes the most serious supply for operating theatres. In the numbers that the required rate of con­ risk of total collapse. A starting point pneumatic building the necessity for struction will preclude the use of would be to establish an effective size of ventilation6 will require the provision orthodox materials, such as and puncture which has a sufficiently small of a controlled leakage valve, which steel, as a sheer impossibility. It is probability of occurring during the could conceivably be shut off during an suggested that factors of safety for limited life-span of the building. emergency situation. In the event of multi-storey, pneumatic buildings must On the reasonable assumption that the membrane being. punctured, the be established on a statistical basis. the membrane would resist tearing and standby plant would automatically come A suitable criterion might be the that the puncture would therefore re­ into operation, and, if necessary, the multiple-engined aircraft, which is cap­ main localised, it only remains to ventilation valve could be closed. able of operating with part of its power provide pressurisation plant of sufficient Accordingly, three to four times the system out of action. This would imply capacity to maintain adequate air­ normal pressurised air-input would be that pneumatic buildings will require pressure in the building, before the available instantaneously. Further, it is strict maintenance and inspection pro­ puncture is repaired. The provision of highly unlikely that the building would grammes, similar to those now applied standby plant operating from an alter­ be fully loaded at this critical time, or only to mechanical products. For the native energy source is mandatory. indeed at any time during its life-span.

114 BUILD Intel"llational. March/April 1971 •

_BEARI NG FLOOR FIXED safety consideration in multi-storey, pneumatic buildings of the type shown f-­ - in Fig. 3. No doubt it will be necessary SUSPE NDED CURTAIN WALL OR MEMBRANE to provide a clear air-space around the N perimeter of a pneumatic building, so V that radiation from external fires will I:>:LOO RS SUSPEND ED f-­ FROM BEARING FLOOR not impair the membrane wall. Similar -­ / town- regulations are presently being enforced in a number of countries BUILDING ENVIRONMENT for buildings of orthodox construction. -tiQI PRESSURIZ ED - However, the danger is much more MEMBRANE AND critical from fires which might start DIAGONAL TENSION NET inside the building. In the case of small flames which might originate from PRESS URIZED TUBE cigarette lighters or matches, it is f­ sufficient for the membrane to be spark­ -- proof. Most commercially available membrane materials comply with this ..... I""" ENTR ANCE requirement and some (e.g. teflon­ coated) can withstand temperatures up ...... ... .:~ to 500°F. Apart from the existence of a small -SERVICE PLANT - gap of 1-2 ft between the membrane and the perimeter of the floor (Fig. 3), it is envisaged that suitable heat-resistant coatings could be applied to the internal

~---RIGID WALL surface of the membrane if required. Larger fires will emit radiation from which the building membrane must be shielded. For this reason, it is convenient ALL SERVICES AND to allot a further function to the sliding FIRE ESCAPE partitions provided at the circumference VERTICAL TRANSPORT of each floor for acoustical and visual reasons. It is intended that these

HIGH PRESSURE TUBE screens be fire-rated and automatically controlled by a smoke- or heat-detection system. Accordingly, each floor may be completely sealed off as a separate com­ partment.

o 10 20FT The possibility of assigning a limited, ~ structural application to these partitions Figure 11 High pressure central core supports suspended floor system and allows has been considered, but temporarily building environment to remain at atmospheric pressure rejected on economic grounds. In any case, the time taken for this compart­ mentation process to be completed must be minimised. At the same time, both This suggests that a pressure less than Australia, is a compromise solution and the design pressure (50 % might be a should be acceptable to building authori­ reasonable estimate) would be required ties in any country. to stabilise the building at this time. The central column in the unpres­ Consideration has also been given to surised condition is just capable of a number of related building types in­ supporting the self-weight of the build­ corporating pneumatic, cellular struc­ ing and a limited live-load. When tures (Figs. 10 and II) in which the pressurised to 30 psig, the building building environment is not pressurised. structure incorporates a factor of safety For these the risk of total collapse is similar to orthodox systems of con­ much reduced, although naturally at the struction. Even in this limited form the expense of structural efficiency. The pneumatic structure leads to consider­ three-storey residential building shown able economies, although an unreason­ in Fig. 12 is supported by a rigid ably high price has been paid to comply Figure 12 Typical application of high membrane, central column pressurised with present standards of safety. pressure central column system to three­ hydrostatically to 30 psig, and fabricated storey residential construction (central from t in (thickness) mild steel plate. The fire hazard column 6 ft diameter; t in steel plate This building, which is proposed to be In fact, it is the potential fire hazard membrane; column pressure 30 psig; erected by architecture students in which has emerged as the most critical building diameter 32ft)

BUILD International, March/April 1972 115

d -

multi-storey PRESSURE TANK air-supported ~ building construction ....----' L-c....

I I I , _II"" ... FEED ~~COE;~~/ ~LOW PRESSURE / " SPRINKLE RS /

,/ " ~, / " ,/ " / ,/ I-;TAND_ HIGH PRESS URE " / "X PIPES ~PIPES AT PE RIPHERY / , ~---- / " ,---- high-pressure and low-pressure sprink­ ---­ "­ lers (Fig. 13) activated by the same ~USPENDED ~' detection system will come into opera­ FLOORS SLIDING _ tion. The high-pressure sprinklers will PARTITION deluge the membrane and external surface of the fire-rated partitions as they slide into place, while low-pressure sprinklers will spray the entire floor area " ,/ '. of the sealed compartment. At this ' ... '\. '\'" " ,/ ..... time or after a specified degree of danger " / " / has been reached, an alarm system will " '\, / ,/ warn occupants to evacuate to a fire­ SIAMESE CONNECTION ..... ~ / FOR FIRE BR IGADE ,/ rated, self-supporting shelter at base­ ment level. Escape from this mass : shelter to the outside will occur through " ..... '. " ". , . ".'.:~WAT~~ one or more emergency airlocks, '.' PUM~I~ SERVI CE .' ~ ,"'lII continuously throughout the duration , , ...... ; I.':'" ..... of the fire. Apart from these precautions, it is envisaged that the normal require­ Figure 13 Fire-protection installation for single-skin, membrane-cable-network ments of alternative means of escape (to building showing fire-rated sliding partitions and sprinkler systems the basement shelter), fire-rated stair­ cases, etc., will apply equally to multi­ storey, pneumatic buildings. rigid membrane buildings are stable in theoretical calculations have indicated Rigid membrane buildings themselves, provided the cylindrical wall that for spans (i.e. diameter) of 60-80 ft Multi-storey, pneumatic buildings in­ is sufficiently thick. the self-weight of the floor structure corporating rigid membranes (i.e. tin­ Although the structural variations could be reduced to less than 15 psf per plate, rigid PVC, etc.) fall into two illustrated in Figs. 14, 15, 16 and 17 floor area. Model tests on such light­ classes, namely buildings in which the appear to differ only marginally from weight, pneumatic, cable floors are habitable spaces are pressurised as the flexible membrane building types dis­ scheduled to be conducted in the near shown in Figs. 14 and 15, and build­ cussed previously, in respect to the future. ings in which the habitable spaces are design and integration of mechanical 2. The rigid membrane column will under ambient atmospheric conditions services, construction techniques 6 and resist lateral fluid pressure applied (Figs. 16 and 17). When the building , there are nevertheless a externally to the curved surface. 7. 1 This environment is pressurised, normally number of secondary considerations particular property is of importance in the entire building enclosure acts as a which apply to rigid membrane con­ the type of pneumatic building shown short pressurised cylindrical shell under struction, alone. in Fig. 17, where floors are supported axial compression (i.e. the building load) 1. Individual floors may be attached by a pressurised annulus, while the and lateral wind load. directly to the rigid, membrane wall building environment remains at atmos­ In the case of a rigid membrane we are (Fig. 14). Therefore, it will be possible pheric conditions. able to calculate the required internal to. develop a built-in floor system, 3. Rigid membranes will allow the pressure as a function of membrane allowing complete continuity between designer to increase the material thick­ thickness rather than total building load. floors and building enclosure. Some ness well beyond the limits which must Since the cylindrical shell is self-sup­ thought has been given to the develop­ apply in the case of flexible membranes. porting in the deflated state, pressurisa­ ment of cable-network floor systems for It will therefore be possible to employ tion will serve to extend this range of incorporation in multi-storey, pneu­ inherently weaker materials with other, stability to include the case of super­ matic construction. It is intended to more advantageous, properties. imposed loads, by increasing the critical provide the required reaction at the 4. Whereas an exterior cable-network buckling stress of the shell. Whereas periphery ofeach floor (where the cables has been proposed for the reinforcement flexible membrane buildings derive their are supported) by means of fluid pres­ and bracing of flexible, membrane form and resistance to buckling, torsion sure, thus obviating the need for a heavy buildings, a similar procedure may be and bending from the internal pressure, edge-beam construction. Preliminary, adopted in the case of rigid membrane

116 BUILD International, March!April 1972 i!£!ZL •

RIGID MEMBRANE SUSPENDE D FLOORS ATTACHED TO DOM E

FLOORS SUSPENDED FROM MEMBRANE AT RIGID MEMBRANE· EACH LEVEL

BUILDING ENVIRONMENT BUILDING ENVIRONMENT PRESSURIZ ED PRESSURIZED

SERViCEs ALL FLOORS SUSPENDED FROM DOME

SERVICES VERTICAL TRANSPORT -'---SHAFT VERTICAL TRANSPORT SHAFT

AIRLOCK ENTRANCE AIRLOCI<. ENTRANCE

-:':. :.: ;.: >:.,

..," , ,'~

SERVIC E PLANT SERVICE pLANT

Figure 14 Rigid. membrane building with built-in floor system Figure 15 Rigid. membrane building with suspended floor system. Cable loads are distributed over dome surface by edge beam or equivalent

SUSPENDED FLOORS SUSPENDED FLOORS 1~02~~1-1st~~llS1~- ATTACHED TO TRUSS ~ LEVERATTACHED TRUSSES TO CANTI­

PRESSURIZED RIGID SUSPENOED FLOORS MEMBRANE ANNULUS

HIGH PRESSURE RIGID MEMBRANE COLUM N ...J...J.-_r_-SUSPENDED FLOORS

BUILDING ENVIRONMENT liQ.I. PRESSURIZED BUILDING ENVIRONMENT , . l..-I--+--t--liQI PRESSURIZED

SE RVI CES SERVICES AND LIFTS -f--l--r--

NON STRUCTURAL WALL VERTICAL TRANSPORT l..-I-4--t--SHA F T

SERVICE PLANT ~_=:-__ SERVICE PLAN T

Figure 16 High pressure, rigid, membrane, central core sup­ Figure 17 Rigid, membrane, annulus construction; inside skin suspended floor system. Building environment is not ofannulus su~;ected to hydrostatic compression pressurised

BUILD Interoatiooal. MarchiApril 197Z 117 -

multi-storey air-supported building construction

...._-.-•...... •••• ra ....•••• ...._-'__-_I •...... i I ...... _--__--,I .... •••__.I__ I! '•••• ... __,'-iJI···· ....,_-•I•....

. '.~ .:.. ' .. Figure 18 Typical pressurised, rigid membrane buildings. Figure 19- Possible non-structural and structural enclosures/or Hoop rings and dome shaped roo/are a direct result 0/structural rigid, membrane buildings in which the habitable spaces are not considerations (areas shown black are transparent) pressurised

structures using circumferential and membrane buildings will be able to draw and , Journal of the Build­ longitudinal stiffeners. Although it is on a number of interesting and func­ ing Science Forum of Australia, June 1967, pp. 5-8, Sydney. tional themes, which highlight the unlikely that an optimum solution will 40 POHL, Jo Go, 'Pneumatic structures', be obtained by giving primary structural combination of transparent and opaque Architecture in Australia, August significance to such stiffeners, never­ surfaces. The distinctive features 1968, 57(4), pp. 635-9, Sydney. theless a reinforced system may be (Fig. 18) such as dome- and 3. POHL, J. G., 'The structural, pres­ favoured where the resistance of stress double-storey exterior tension rings surised, flexible membrane column', Architectural Science Review, June concentrations (e.g. due to the attach­ occur as a direct consequence of the 1970, 13(2), PPo 49-64, Sydney. ment of floors to the membrane) or the intrinsic characteristics of this form of 50 DEWEY, A Wo, 'Decompression sick­ minimisation of direct solar penetration, pneumatic construction. ness, an emerging recreational hazard', are major design criteria. The New England Journal ofMedicine, 1962,267(15) and (16). There has been much interest recently 6. SMITH, P. R., and POHL, J. G., in the rediscovery of Van Der Neut's8 'Pneumatic construction applied to early theoretical observations regarding multi-storey buildings', Progressive stiffened cylindrical shells under axial Architecture, September 1970, pp. 11()...7. compression. His findings, now well 7. NASH. W. A, 'Effect of large deflec­ confirmed by test data,9 included the tions and initial imperfections on the supposition that external stringers are buckling of cylindrical shells subject much more effective than internal to hydrostatic pressure', Journal of stringers in stiffening a cylindrical shell References The Aeronautical , April 1955. against buckling. 1. POHL, J. G., 'Pneumatic structures­ 8. VAN DER NEUT, 'General suitability architectural application with special of stiffened cylindrical shells under Sample elevational treatments are reference to multi-storey buildings', axial comprehension', Nat. Luch­ shown in Figs. 18 and 19 for pressurised Ph.D. Thesis, Dept of Architectural traartlab, 13, Repr. 8.314; 1947. and unpressurised building environ­ Science, University of Sydney, Aus­ 9. HUTCHINSON,J. W.,andAMAZIGO, tralia, 1969 (unpublished). J. C., 'Imperfection-sensitivity of ments incorporating structural and 20 POHL, J. G., 'Multi-storey pneumatic eccentrically stiffened cylindrical non-structural enclosures. It is apparent buildings as a challenge to the plastics shells', Harvard Uni. Rep. SM-10; that the designer of multi-storey rigid industry', Australian Building Science April 1966.

118 BUILD International, March/April 1972