Building with Arches - Inhalt - Hypotheses.org · catenary vault is very common as its form gives...

2 The Basics of Building with Arches, Vaults and Cupolas

The Basics of Building with Arches, Vaults and Cupolas

A SKAT publication, Swiss Center for Development Cooperation in Technology and Management, 1994.

Authors: Thierry Joffroy, assisted by Hubert Guillaud, architects researchers, CRATerre-EAG

Contributions by: Patrice Doat, Alexandre Douline, Josep Esteve, Philippe Garnier, Hugo Houben, SergeMaïni, Pascal Odul and Vincent Rigassi of CRATerre-EAG.

and with the opinions of: John Norton, Development Workshop ; Roland Besenval, CRAO-CNRS ; MyriamOlivier, ENTPE de Lyon ; Gernot Minke, University of Kassel ; Kiran Mukerji,Planning and Building in the Tropics. Editing by Karl Wehrle and Heini Müller; SKAT

Available at: SKAT-Bookshop, Vadianstrasse 42, CH-9000 St. Gallen, Switzerland,Fax. +41 71 23 75 45

The town of Thera, on the island of Santorin in the Cyclades, Greece

The Basics of Building with Arches, Vaults and Cupolas 3

CONTENTS

Project of the architect Hassan Fathy, villa at Fayoum, Egypt, 1984


ARCHES, VAULTS AND CUPOLAS

A thousand-year oldtechnologyThe use of arch, vault and cupolabuilding systems in construction canbe traced back to most ancienttimes. As early as the 3rd milleniumBC, they were very widely used inthe countries of the Middle East andEgypt.Arches, vaults and cupolas werealso fairly widely used by Roman,Sassanid and Byzantine buildersbefore being adopted in manyregions of Europe.Very many applications alsoemerged in North Africa, the Sudan-Sahel belt of Africa, as well as in thenorthern regions of China.Many of these countries still boast arich heritage of this kind of building,both in urban and in rural areas. Inmany cases, building them is still aliving tradition, well suited to modernpopular housing needs.

Recent projectsForgotten by the formal buildingsector since the appearance ofconcrete, arches, vaults and cupolaswere rediscovered in the 40’s by theEgyptian architect, Hassan Fathy,who found inspiration in the popularNubian tradition for the design andconstruction of the village of NewGourna.The international success of thisproject, and of other Hassan Fathyachievements, rekindled a renewalof interest amongst architects.Realizing the significant potential ofthese architectural models, somedevelopment project managers havere-launched the use of arches, vaultsand cupolas.These programmes, have enabledthe construction of many buildingsmeeting the varied needs of differentcountries.

DiversityThe numerous types of arches,vaults and cupolas allow a greatvariety of architectural models.As a result, the technology can adaptto the most varied climatic condi-tions: zones which are arid or rainy,cold or hot.Although arches, vaults and cupolasare traditionally used to cover limitedspaces, they are perfectly well-suited to build much larger spaces,up to tens of meters. Thus they canmeet the needs of any buildingprogramme, public or private, low-cost or quality housing, granaries,warehouses, shops, schools, public,religious buildings, etc.

House built with "Nubian vaults" in adobe bricks near Aswan, Egypt


TRADITION, PRESENT AND FUTURE

SuitabilityArches, vaults and cupolas can oftenprovide a good solution for coveringall kinds of buildings of all sizes.However, their acceptability andsuitability to genuine needs and localclimatic conditions cannot always betaken for granted.This means that preliminary surveysare required. These enable one tochoose the correct option and selectsuitable technical solutions.In order to ensure that structures arewell designed and well built, special-ized training must be given at alllevels: design, engineering andconstruction.

Mastering the technologyThe experience acquired over thelast twenty years has allowed thedesign and construction of buildingsusing arch, vault and cupolastructures to be mastered onceagain.The technology is now used inseveral areas of the world: the Sahelbelt of Africa, the Near and theMiddle East, India, Central America.Initially launched in Niger, the“Woodless Construction” pro-gramme suggests simple technicalsolutions, well-suited to the localcontext, and follows a policy ofresearch and training which ensuresa major impact amongst local people.Winner of the “Habitat” Award1992, this programme is now spread-ing to other countries of the Sahel.

Research and developmentEven though arches, vaults andcupolas are already well known,research and development pro-grammes are being carried out,mainly in four areas:1 - systematic identification of

models and types, and the variousways of using them ;

2 - suitable tools to substitute for theknow-how of traditional builders ;

3 - perfecting simplified methods ofcalculation ;

4 - techniques to prevent rainwaterinfiltration: water-proofing, run-off, surface maintenance.

Project of the architect Hassan Fathy, built in 1981 in New Mexico, USA


ARCHES, VAULTS AND CUPOLAS

Deficiency of traditionalroofsIn many countries, good qualitywood required for the constructionof traditional roofs is no longeravailable in sufficient quantities. Thisresults in the use of poor qualitywood, imports, or even turning toconventional modern techniquessuch as woodworks covered withcorrugated iron sheets or concreteslabs.Gradually these conventional moderntechniques have emerged as the onlyalternative to traditional ones.

Disadvantages ofconventional moderntechnologiesIndustrial products such as asbestossheets and corrugated iron are notalways well suited to local conditions(heat, cold, noise, appearance, etc.)Often imported or even produced incentralized units, they encourage lowskill levels more than job creation.Building systems based on the use ofreinforced concrete consume largeamounts of expensive materialssuch as cement, steel, timber forformworks, as well as sand andgravel which are not always locallyavailable. This places them out ofreach of the vast majority of localinhabitants.

An alternativeTraditional techniques, adaptations ofthese, or newly imported techniquesdo not always provide a solution toroofing needs in harmony with localconditions: cultural, climatic or eveneconomic.As a result, alternative roofingsolutions are needed. Building witharches, vaults and cupolas is, inmany instances, one of these solu-tions.Their numerous variations and widerange of architectural solutionsenable them to be adapted to verydiverse situations.

Advantages of arches,vaults and cupolasThe materials used for the construc-tion of arches, vaults and cupolascan be the same as those used forwalls and can be found or producedlocally. Construction is therefore lessexpensive, creates jobs and allowsforeign currency savings.There is no use of wood, which alsototally eliminates the risks of fire.The massive nature of these struc-tures provides good heat storagecapacity and delay in heat transmis-sion, meeting comfort requirements,especially in dry climate regions.This mass also gives good soundinsulation.

Research centre, Dakar, Senegal

Information and reception centre of Auroville, India;International Hassan Fathy Award 1993


ADVANTAGES AND POSSIBILITIES

Economic considerationsThe cost of buildings using arches,vaults and cupolas varies accordingto the materials employed, thecomplexity of the design and of theconstruction technique, the size ofthe structures, and the surfaceprotection used.However, buildings employing sun-dried earth bricks (adobe) andprotected with an earth render canbe built at a lower cost thantraditional buildings of a similarstandard.In general, arches, vaults andcupolas made from water-resistantmaterials and protected by durablewater-proofing cost more thansimple buildings covered with roofsheeting, but remain less expensivethan buildings with reinforcedconcrete slab roofs.

Job creationBuilding with arches, vaults andcupolas is highly labour intensive.Therefore, the technology has greatjob creation potential, not only withregard to construction, but also withregard to building materials produc-tion.

Foreign currency savingsThe basic materials are generallyavailable on site, and little power isrequired for processing them.Significant foreign currency savingsare possible. Transport costs arealso reduced.The investment in site equipment,centering, compass, scaffolding, isgenerally very small, and most ofthese can be manufactured locallywithout any major difficulty.

Crossed arches, Zaria, Nigeria

Great aesthetic potentialThe many possibilities of forms,sizes, combinations of differentelements and types of finishingenable highly attractive spaces to becreated. Thus arches, vaults andcupolas can be used not only forlow-cost housing programmes, butalso for high quality, luxurydwellings.

Limitations of useSome local conditions can limit thebenefits of building with arches,vaults and cupolas:� rejection by the inhabitants for

cultural reasons,� high cost of labour,� high cost of suitable building

materials,� use in earthquake areas requires

special care,� lack of building norms.The technology must be adjusted toa given context and the techniquesmust be mastered, to warrant theadvantages of using arches, vaultsand cupolas.

"Woodless construction" project in Niger: simple but adapted structures


ARCHES AND THEIR USES

Forms of archesThere are many shapes of arches.These are mainly characterized bythe curve of the intrados and theratio of height to span.Most arches are connected to thewall by the extrados. The corbelarch, built using courses graduallyjutting further out, and monolithicarches, whether poured, tamped orcut out, have no extrados andcontinue directly on from the wall.

A partition arch (3) serves as aloadbearing element in a large roomby supporting roofing elements ofrestricted length, joists, purlins oreven vaults or cupolas.An arch can serve directly as thespringer of a cupola (4). In this casethe forms of the arch and of thecupola are closely interlinked.

Varied uses of archesThe main function of an arch is tobridge an opening in a wall.By juxtaposing and repeating archesresting on pillars, one can obtainarcades (1), which allow one tocreate very open covered spaces.Arcature, or blind arches (2), can beused to lighten the masonry structureor simply for decorative purposes.

(1)

(2) (3) (4)


VAULTS

Forms of vaultsThere are a great many forms ofvault. The simplest are barrel vaultswhich in fact consist of a successionof identical arches. Barrel vaults canhave steeper or flatter profiles: semi-circular, segmental, ogival. etc. Thecatenary vault is very common as itsform gives maximum stability for aminimum use of material.

Combining two barrel vaults with thesame profile allows two other typesto be defined: the “groined vault”and the “Dominical vault”. Byprolonging one of the two barrelvaults, the “Dominical vault”becomes a “trough vault”. Combin-ing barrel vaults with differentprofiles forms a “lunette vault”.

A “Dominical vault”, the ribs ofwhich are rounded in the form ofcones starting from the corners,becomes a “squinch vault”. Similarlythe “trough vault” can evolve into a“boat vault”.


CUPOLAS

Forms of cupolasCupolas are obtained by rotating anarch, except for faceted cupolaswhich more closely resemble theDominical vault. A cupola can besemi-circular, segmental, ogival,conical, etc.

Cupolas are circular in plan. Theycan, however, be used to coversquare or rectangular rooms by usingpendentives or squinches. Cupolason pendentives can be used to coverany kind of polygonal shape in plan.

It is possible to combine severalcupolas or to combine cupolas withvaults.


USES OF VAULTS AND CUPOLAS

Varied usesVaults and cupolas cover spaceseither with or without recourse towalls or other supporting structures.They are, however, merely struc-tures. They become a roof-coveringonly if they are given a waterproofcoating.Flat or slanted roofs and flooring canbe easily obtained by infilling therounded forms.Small span barrel vaults builtbetween girders, known as vaultingcells or jack arches, can be used forflooring.

Rural housing near Lake Titicaca, Bolivia Adobe vaulting cells

Civil servant accomodation, Kamboincé, Burkina Faso

Stone barn with flat-stone roof, Causse Méjean, France Farm building using several levelsof ribbed vaults, Queyras, France


DEVELOPMENT PROJECTS

Housing and developmentIn the context of applying a develop-ment policy, programmes implement-ed by government and non-govern-ment organizations aim not only toproduce buildings, but also to have aspin-off effect on people’s socio-economic situation.Apart from the requirements ofhousing programmes, job creationand the preferential use of local rawand building materials are the maintechnical objectives that building witharches, vaults and cupolas can meetperfectly.

Preliminary actionsPreliminary surveys, as well asvarious stages of experimentationand training, will ensure a successfulimplementation.Where no tradition exists, prelimi-nary surveys represent a significantinvestment. As a result, organiza-tions play a major role, as sufficientlywide programmes enable thisinvestment to be amortized.

ImplementationThe implementation of a buildingprogramme should always form partof a development approach andstrategy.In all cases, the professional trainingwhich is given during project imple-mentation is an asset which canbenefit the whole community.Involving local tradesmen, entrepre-neurs, architects, engineers anddraftmen, ensures the possibility ofspontaneous and correct replicationof the building models proposed andtheir dissemination.

Spontaneous replication of models is a sign of a development project's success; "Woodless construction"programme, Niger


BUILDING MARKET

Focus on building materialsBuilding with arches, vaults andcupolas highlights the potential of thebuilding materials used. Demonstra-tion structures and designs allowtheir quality to be illustrated and theircredibility amongst the public to bereinforced. This can stronglycounterbalance resistance to newmaterials in the marketplace.

Focus on enterprisesBecause it calls for technical knowl-edge and skills, which non-profes-sionals always find impressive, it alsofocuses on the enterprises involvedand confers upon them a favourablequality image.

QualityThe quality of a building depends onthe quality of the basic materials andof the building work. The durabilityof the structure will be linked tosurface protection or water-proofingbeing carried out well.To ensure the quality and durabilityof the building, the contractor shouldcarefully control site supplies andwork. In addition, the client shouldbe informed about any requiredmaintenance of the surface protec-tion, frequency and technique.

New marketsLaunching into building with arches,vaults and cupolas can open newmarkets, public or private, especiallyif the launch takes place in conjunc-tion with pilot promotion programmesrun by organizations.

InvestmentInvestment is generally very low asthe equipment required is simple andcan be manufactured locally.On the other hand, in order to ensurea good quality of his achievements,the entrepreneur will have to investin training his employees. Thisinvestment will be balanced by thequality of the realization.

An attractive technology; private house, Marrakesh, Morocco


KEY QUESTIONS

If you are interested in building with arches, vaults and cupolas, you should be aware of theimplications that follow on, with regard to:

� acceptability of architectural models,� building materials,� building skills,� costs, management and investment .

10 key questions

1 - Is there a demand for an alternative roofing solution or for an improvement in traditionaltechniques of building with arches, vaults and cupolas?

2 - Do you think the people would accept buildings made with arches, vaults and cupolas?

3 - Are suitable building materials available locally or can they be produced?

4 - Do you have a suitable solution for surface protection or water-proofing?

5 - Are you aware that all types of roofing systems need periodical maintenance?

6 - Do you realize that it may be necessary to revise your building methods as a whole?

7 - Is your region prone to specific building problems like earthquakes or swelling soils ?

8 - Are you prepared to make an investment in equipment and in technical surveys?

9 - Are you prepared to pay particular attention to training?

10 - Do you know where you can find technical and training support?

Exhibition centre, Janadriyah, Saudi Arabia


RECOMMENDATIONS

If by assessing the ten key questions you conclude that there is a potential to construct arches,vaults or cupolas, it is recommended to make a fine-tuned feasibility study. This should be madealso in order to elaborate a programme of activities ensuring a successful building with arches,vaults and cupolas.

Feasibility studyIt should be conducted on the following main aspects:

1 - Socio-cultural: demand analysis, acceptability amongst local inhabitants,2 - Economical: living standards, costs, credit, market, loans,3 - Technical: structural and surface protection materials, statics, norms

in force,4 - Climatic and geographical: weather, environment, natural calamaties,5 - Institutional / entrepreneurial: organisations, policies, capability and means,6 - Skill and know-how: experiences, know-how transfer, training possibilities

Further stepsBased on the data gathered through the feasibility study, it will be possible to elaborate recommen-dations and a strategy of work. From experience, a special attention has to be paid to the followingaspects:

1 - Architectural choices:These should be made taking account of cultural references.

2 - Technical choices:They must be adapted to the specific local conditions. The degree of complexity of the buildingprinciples, their flexibility, and their replicability must be taken into account.

3 - Demonstration:Test buildings must be erected. These enable the acceptability of the proposed models to beverified, the technical and architectural choices to be refined, and the overall level of skills andknowledge, and therefore of the quality of built examples, to be improved upon.

4 - Professional training:This should be provided at all levels in order to create teams capable of undertaking projectsfrom design to building stage, as well as the maintenance of the buildings.

5 - Quality control:Good supervision has to be put into place in order to ensure the quality of the constructions.

6 - Technical assistanceFor a minimum period, keeping in regular contact with partners who are experienced and able togive technical help or advice is recommended.

7 - Commercialisation:Promotional and commercial activities might be necessary in order to ensure the minimumquantity of work allowing the amortisation of your investments in the technology.


BUILDING OPTIONSAND ARCHITECTURAL / ENGINEERING DESIGN

Choosing between optionsEach arch, vault and cupola hasspecific properties and technical andarchitectural capabilities. Therefore,it is important to have a goodunderstanding of the various “fami-lies” of building systems and thearchitectural possibilities whichfollow on from these, in order to beable to make a relevant choicebetween options. Such choices,indeed, have a very great influenceon the acceptance and the appropri-ation of the technology. Therefore,attention has to be taken in order tomeet all the different facets of theneeds and constraints of a construc-tion.

BuildingThe various forms of arches, vaultsand cupolas are closely linked to oneor more building methods. They aremore or less inexpensive, dependingon how much specialized equipmentis needed and how difficult theconstruction work is. The issue ofscaffolding is also an importantfactor and can determine the pre-ferred dimensions, notably for theheight of the arch, vault or cupola.

Spatial considerationsThe curved forms generated byarches, vaults and cupolas definefree variable heights which increasewith the span and the rise.Depending on requirements, oneshould first determine the curvatureof the element and the height of itsspring-point.The ability to move between onespace and another also makes itimportant to take account of theability to open out between theinterior and the exterior of a vault orof a cupola. One can distinguishbetween open, semi-open and closedtypes.

Building complexityBuilding systems using arch, vaultand cupola structures can rangefrom the simplest to the mostcomplex. The main distinction to bemade is between modules which areindependent from one another(whether connected or not) andsophisticated systems which respectvery precise geometrical traces.The sophisticated systems enable toget an optimum use of the materialand perform very well from the pointof view of costs. On the other hand,their replicability can be tricky as ahigh degree of precision at the layingout stage is required.As a general rule, the more theshapes of the vaults or the cupolasare visible, the cheaper the building.Certain models permit a simple andinexpensive transition to flat orsloped roofs.


Architectural appearanceArches, vaults and cupolas offer avery great number of architecturalpossibilities with a more or lesstypical and attractive character.These depend on the materials andmodels used, the methods of utilisa-tion, and finally the building tech-niques which are linked to them. Thearchitectural aspect is one of theprinciple vectors of cultural andsocial acceptability of a technology.

AcousticsThe rounded shapes, especially ofcupolas, can result in a significantdegree of reverberation which is anasset or a disadvantage dependingon the intended use of the space.Simple measures, such as corbelledelements or suspended cloth, can beused to reduce reverberation.

Stability of arches, vaultsand cupolasTo ensure stability, the form shouldbe as close as possible to the line offorce. In the case of vaults, forevenly distributed loads, the bestform resembles that of an invertedsuspended chain (catenary). Thisapplies both to flatter and to slenderforms.The corresponding ideal cross-section of a cupola is somewhatdifferent and can only be worked outgraphically or mathematically.Combining vaults and cupolas resultsin more complex issues of stabilityand allows much more flexibility inshape.

Stability of supportsArches, vaults and cupolas areheavy roofing elements and theyexert thrusts which increase with thedegree of flatness, the span and theweight of the structure. Thesethrusts may be concentrated ordispersed. They have a tendency topush out the supporting bases (walls,piers and foundations) and must betaken into consideration. The mostcommon solutions are: cancellingthem out by juxtaposition, wideningthe wall, buttresses, and tie-beams orring-beams.

Details and finishingsDetails and finishings can influencethe choice of structure. Attentionmust be paid to:- the bonding pattern(s), particular-

ly for visible masonry,- channelling and removal of

rainwater,- window frames.

Forms of "inverted chain"

Segmental arches exert greaterthrusts than slender arches

Section of house in Sfax, Tunisia

Designs for various shapes ofbuilding:curved, flat or sloping roofs Project for a 2 classroom block, Senegal

Section of church, Valladolid,Spain


BUILDING MATERIALS

The building materials required forthe masonry of arches, vaults andcupolas can be divided into twobroad groups: solid components(adobe, stone, etc.) and bindercomponents (mortar). The solidcomponents ensure compressivestrength. The binder componentsensure that compressive forces aretransmitted and the cohesion of thewhole.To avoid the risk of shrinkage duringdrying out after building work,preferably a minimum amount ofbinder component should be used.The various solid and binder compo-nents are rarely incompatible but it ispreferable to use components ofsimilar strengths.

Solid componentsStone:Stone is often of very irregulardimensions, which forces one to usevery expensive preparation andimplementation techniques. Soft, lightstone offers interesting possibilities,as does layered stones, which can bestandardized by simply chisellingthem to the required shape.

Adobe block:Simply prepared by moulding plasticsoil and leaving it to dry, the adobeblock is always inexpensive. Itsshape and size can be easilyadapted to the various methods ofconstruction, so that this material isthe most widely used. However, itsrather low mechanical performancesrequire the construction of fairlymassive structures.

Stabilized compressed earthblock:Being insensitive to water andhaving good mechanical strength,this material provides an alternativeto the more costly fired brick. Mostof the presses used to manufacturecompressed earth blocks can beadapted to produce special blocks.

Plain moulded cement blocks:Made from sand-cement mortar,these blocks have been used forvery diverse buildings as manyshapes and sizes of both simpleelements, and also of special parts,can be prepared.

Fired solid brick:This material is more expensive butgenerally performs well, whichallows for either lighter buildings orlarger dimensions. Special shapesand sizes can be obtained, dependingon the means of production.

Fired hollow brick:This enables special applicationtechniques to be used, and very lightbuildings to be realized. Materialsproduced using craft potterymethods can be used in a similarway.

Binder componentsEarth mortar:This is used to bond adobe, firedbrick or stone. Its good stickingproperties enables one to build vaultsand cupolas without shuttering.Plastic earth mortar can be used tomake hand-shaped cupolas.To avoid shrinkage, straw or sand isadded to soils with an excessive claycontent.

Stabilized earth mortar:Cement, lime, plaster or bitumenimprove the characteristics of earthmortar. Such mortars are verysuitable for binding compressedearth blocks or fired bricks.

Lime-sand mortar:This displays averagecharacteristics; its main advantage isthat it stays malleable for quite along time and sets very slowly. Itcan be improved by adding crushedbrick or pozzolanas. Lime-basedmortars are very frequently used inconjunction with fired brick andstone.

Cement-sand mortar:Given the high cost of cement, theamount used must be carefullycalculated according to the mechani-cal strength required. This mortar issuitable for bonding good qualityfired earth and full sand-cementblocks. Having little adherence, it isnot well suited to shutterless buildingmethods, apart from corbelling.Medium-span vaults have beenmade directly using a sand-cementmortar.Small size elements can be prefabri-cated.

Moulding an adobe block into theshape and size required


Gypsum mortar:This sets very quickly, which enablesadhesive application techniques to beused.Small span vaults can be made oreven prefabricated directly using thismortar.The stability of water-solublegypsum can be improved by combin-ing it with lime.

Surface protectionTo avoid infiltrations and thereforerisks of detoriation,vaults andcupolas must be protected fromrainwater, which must be channelledaway from the building, using water-spouts or downpipes.

Renders:An earth render is the least expen-sive, but requires periodical mainte-nance whose frequency whichdepends on the nature and thequantity of rainfall. .A sand-cement mortar is too rigidand will always crack, which allowswater infiltration to take place. Itshould not be used without a comple-mentary membrane.Lime-sand and gypsum-lime-sandrenders are better suited because oftheir greater pliability, but a certainamount of maintenance might stillneeded.

Roof coverings:Certain forms of vaults and cupolascan be protected by roof coveringsmade of thatch, flat stones or eventiles. Although rarely used in recentprojects, these solutions can be veryefficient while remaining cheap.

Membranes:Membranes consisting of a single ormulti-layer bitumen-based material,of waterproof paint or of metalleaves are efficient, but often tooexpensive.

Flat and sloping roofs:A great many solutions are possiblehere, but the choice of the shape ofthe vault will be crucial to thesimplicity of implementation and toeconomic considerations. Thesimplest solution is to use a compact-ed earth and gravel infill, on whichthe water-proof layer is placed, butsolutions including very light woodenstructures are also possible.

Earth plaster is efficient but oftenrequires maintenance

Ensuring water run-off through awater-spout

Tiled roof cover

Multi-layer water-proofing


EXECUTION

Building archesWith formwork:For building an arch, a formwork ofthe same shape of its intrados needsto be used. This can be made ofwood or metal and should be used inconjunction with a system allowingits easy removal.For most arch forms, the formworkcan be removed immediately afterconstruction. The formwork cantherefore be reused straightaway.This means that if there are a greatmany identical arches to be built,clearly it makes sense to prepare aprecise and robust formwork toensure that it can be reused and thatthe work will be of high standard andcarried out quickly and economically.Building up bricks or blocks with dryjoints and shaping the curve with alayer of mortar is a very economicalway of making a formwork.

Without formwork:Corbelled arches are built usingcourses which each jut out furtherthan the previous one. Cut outarches, and arches shaped withwooden reinforcement, are also builtwithout formwork.

Building vaultsVaults can be built in a similar wayto arches.

With formwork:Building can be done on a fullformwork set up in place. This ismainly used for floors over base-ments.It is possible to use an integratedformwork. Being very heavy, thishas to be assembled and dismantledin place. This technique iseconomical only if the vaults - andtherefore the formwork - are light.

Sliding formworkBrick formwork

Wooden formwork

Metal formwork

Corbelled arches


Sliding formwork:Building takes place in stages, withthe formwork being repositioned asoften as necessary. This is one ofthe most interesting methods, butapplies only to barrel vaults.

Without formwork:Corbel vaults can be built only usingsmall spans.Building in so-called “slices”, withoutformwork, is the most economicalmethod. This exploits the propertiesof certain mortars which enable thebricks to be laid face on layersleaning at a steep angle to thevertical. To improve adhesion, smalland fairly thin elements of regulardimensions should be used.Using this principle, and by varyingthe shape and the size of thecourses, one can build barrel,groined, dominical, trough, squinchand boat vaults.Traditionally, all these vaults are built“by eye”, but light tools can be usedto guide the masons so that theybuild the required shape correctly.

TOOLS AND SKILLS

Building cupolasBuilding techniques without form-work are always prefered as aformwork would be too complicatedto manufacture.

Corbelling:This enables large areas to becovered, but results in conical formswhich are very high relative to thespan.

Increasingly inclined rings:Horizontal rings which graduallydecrease in diameter can be used tocreate all types of cupolas. Thismethod uses the same brick-layingtechnique as for vaults built in“slices”.Simple rotating guides which de-scribe the form in the air can beused to obtain correct, regular forms.

Hand shaping:Using a straw-reinforced earthmortar, it is possible to build fairlylarge sized cupolas. These are builtup in successive layers.

Squinch vault

Building a barrel vault in "slices"

Building a cupola using inclined ring-courses


PROFESSIONAL TRAINING

After theoretical training, learning on site is vital to acquire real skills

The need for trainingCurrent training courses teach verylittle about the particularities ofarches, vaults and cupolas and abouttechniques to build them. Specificprofessional training has to beprovided for all concerned, fromdesigner to builder.

“Design know-how”Designing buildings with arches,vaults and cupolas calls for specificengineering knowledge, principallyincluding spatial geometry andprinciples of stability. The varioustechnical solutions or architecturalvariants also need to be known inorder to enable the technology to beadapted, to be used creatively and toevolve.

“Building know-how”Although the main masonry princi-ples apply, specific building tech-niques must also be used. Eventhough these call for some tricks ofthe trade and specific tools to beused, these techniques are quitesimple, and they can be masteredvery quickly.Structural principles should also bewell understood, so that adaptation tospecial or new situations can occur.Although formal training will alwaysremain the most efficient, on-the-jobtraining on sites supervised byqualified staff is a good way ofacquiring practical skills at anaffordable cost.


PROJECT MANAGEMENT

The marketThe construction market is in generalvery conservative and it is notalways easy to introduce new ideasinto well-established contexts.Promotional activities might have tobe undertaken to penetrate themarket.

Promoting and informingDemonstration projects are neces-sary. This means that opportunitiesto construct “show” buildings mustbe found. High standard buildingsare of interest, because they areappreciated by the general publicand can be designed and built usingsimple principles, which can then beexploited for more economicalhousing.

The public needs to be made awareof the possibilities which are offeredby buildings with arches, vaults andcupolas. Awareness-raising activi-ties, showing their full potential, canbe considered around the firstbuildings.Dissemination activities made bytrained professionals is very efficientand effective.

Ensuring qualityTop quality work is important to gainpeople’s confidence. Particularattention should be paid to thecontrol of site work: execution,planing, raw and building materials,and maintenance of equipment.

Site managementBuilding with arches, vaults andcupolas does not pose any particularmanagement problems.However, two points can be ofimportance: special equipment andbuilding seasons.

Special equipmentSpecial equipment (e.g. arch form-work) is not found in the normalbuilding materials trade. Manufactur-ing it to avoid building delays willhave to be planned in advance.To ensure a good amortization of theequipment, planning at the designstage can allow for using equipmentseveral times in the same building, orin different buildings, by repeatingshapes and using standard dimen-sions.

Building seasonsEven if the materials used arewater-resistant, the building planningshould preferably allow for thewater-proofing to be done beforerainfall periods, which can then bedevoted to inner finishing works.Quality of finishings, a major

asset

Good organization enables work tobe carried out quickly; site of ahouse built in 24 hours


SELECT BIBLIOGRAPHY

Office building of the Center of Energy Studies at the Indian Institute of Technology, New Delhi, India

ADAUA. Rapport sur les techniques de construction mises au point par l’ADAUA entre 1977 et 1982 pour la promotion desmatériaux locaux africains. ADAUA, 1982.

Besenval R. Technologie de la voûte dans l’Orient ancien. Tome 1 and 2. “Synthése n° 15”. France, Paris, Editions Recherche surles Civilisations, 1984. Tome 1 : 196 pp., tome 2 : 224 pp.

CRATerre, Doat P., Hays A., Houben H., Matuk S., Vitoux F. Building with earth. India, New Delhi, The Mud village society, 1991.284 pp.

CRATerre, Houben H., Guillaud H. Earth construction, a comprehensive guide. United Kingdom, London, Intermediate Technolo-gy Publications, 1994.

CRATerre : Dayre M., Doat P., Estève J., Guillaud H., Houben H., Joffroy Th., Rollet P. Toitures en terre. Tome 1. Arcs, voûtes etcoupoles. Paris, France, Rexcoop, 1986. 247 pp.

Dellicour O., El Jack K., Posma L., de Walick P. Le centre de formation agricole de Nianing. Sénégal, Dakar, Dakar Regional Officefor Education in Africa, 1978.

Department of Housing and Urban Development, Office of International Affairs. Mud brick roofs. Ideas and methods exchange. n°42. USA, Washington, Department of Housing and Urban Development, Office of International Affairs, 1957. 14 pp.

Development Workshop. Les toitures sans bois, guide pratique. France, Lauzerte, Development Workshop, 1990. 77 pp.

Fathy H. Architecture for the poor. An experiment in rural Egypt. USA, Chicago, The University of Chicago Press, 1973.194 pp. + annexes.

Norton J., Tunley P. Vulgarisation de la construction de voûtes et coupoles au Sahel. Phase 1 : l’identification de besoins.Suisse, Gland, L’alliance mondiale pour la nature (UICN), Programme Sahel, 1990. 46 pp.

Steele J. Hassan Fathy. Architectural monographs 13. United Kingdom, London, Academy Editions, 1988.


REFERENCES AND SOURCES

Unless otherwise stated, all photographs are by the author. Illustrations: Patrick Idelman.From left to right and up to down.Front cover: Construction of a 9 m diameter “star” cupola in compressed earth blocks, Calvi, Corsica, France.

p.2 The town of Thera, on the island of Santorin in the Cyclades, Greece.p.3 Elevation of the “Andrioli house”, Fayoum, Egypt, 1984, in Hassan Fathy, Architectural Monographs, see bibliography. p.4

House built in adobe bricks near Aswan, Egypt; photo: P. Doat.p.5 Dar al Islam community building, Abiquiu, New Mexico, USA; a project of architect Hassan Fathy; photo: P. Odul.

Postage stamp issued in Niger in 1992 on the subject of “Woodless Construction”.p.6 Experimental building at the Rural Housing Research Centre, Dakar, Senegal.

Information and reception centre of Auroville , India; architects: S. Ayer-Guigan and S. Maini; photo: S. Maini.p.7 Interior of St. Bartholomew church, Zaria, Nigeria.

House built using principles suggested by the “Woodless construction” project, Niger, designed and built by P. Tunley ofDevelopment Workshop; photo: A. Douline.

p.8 Arcatures of provisional mausoleum for Indira Gandhi, India; architects: S. Patara; photo: H. Guillaud.Rural house in the Dades valley, Morocco.Interior of reception building, “Village au bout du monde”, near Mâcon, France.Interior of 24-hour house, Grenoble, France.

p.11 Rural housing on the shores of Lake Titicaca, Bolivia; photo: Th. David.Adobe vaulting cells on palm trunks, Marrakesh, Morocco; photo: P. Doat.Administrator’s accommodation, training centre for rural supervisors, designed and built by ADAUA, Kamboincé,Burkina Faso.Barn, Causse Méjean, France; photo: G. Beraldin.Farm in the Qeuyras region, France.

p.12 Village Development Centre built using principles suggested by the “Woodless construction” project, Niger, designedand built by P. Tunley of Development Workshop; photo: A. Douline.

p.13 Private house, Marrakesh, Morocco, designed and built by architect E. Mouyal.p.14 Exhibition centre, Janadriyah, Saudi Arabia, designed and built by CRATerre-EAG.p.18 Making special adobe blocks for the construction of cupolas, Marrakesh, Morocco.p.19 Multi-layer water-proofing, PanAfrican Development Centre, designed and built by ADAUA, Ouagadougou, Burkina

Faso.Maintaining the earth render of the roof of the Zaria mosque of the Jos museum, Nigeria.Dome and water-spout of house in the town of Tozeur, Tunisia.Tiled roof cover of small church on the island of Santorin, Greece.

p.20 Wooden formwork, Ivory Coast; photo: Ph. Romagnolo.Corbelled arches, Passamainti, Mayotte.Metal formwork, Auroville, India; photo: S. Maini.Brick formwork, building exercise, School of Architecture, Grenoble, France.Construction with a sliding formwork, CSTB, Grenoble, France.

p.21 Building a barrel vault in “slices” using a light-weight guide, building exercise, Grenoble School of Architecture, France.Building a squinch vault, Tabas region, Iran; photo: Abedini Rad.Building a cupola using increasingly inclined ring-courses, near Mâcon, France.

p.22 Building a cupola using a guide, Office building, IIT, architect: G. Minke, energy concept: N.K. Bansal, India; photo: G.Minke.Builders’ training on the site of the 24-hour house, built by CRATerre-EAG with AFPA, (the Adult ProfessionalTraining Association), Grenoble, France.Idem.

p.23 Site of the 24-hour house.Private house, Marrakesh, Morocco, designed and built by architect E. Mouyal.

p.24 Office building financed by GTZ/GATE; architect: G. Minke, GhK, Germany; energy concept: N.K. Bansal, IIT, India;photo: G. Minke.

Back cover: Stages in the construction of the 24-hour house, CRATerre-EAG, Illustration: J. Esteve.


BASIN NETWORK


If you are looking for more information on building with arches,vaults and cupolas

To share your own experience in this field

Don’t hesitate to contact us

BASIN

WHO MAY BE INTERESTED IN THIS BOOKLET?Decision-makers, architects, engineers, project managers, building entrepreneurs,and all who wish to know more about building with arches, vaults and cupolas.

WHAT YOU CAN FIND IN THIS BOOKLET?Basic information about building with arches, vaults and cupolas.The advantages and limitations of arches, vaults and cupolas.Recommendations, bibliographic references and addresses for getting more informa-tion.

WHAT YOU WILL NOT FIND IN THIS BOOKLET?Detailed technical information.Information relating to local conditions.

Building with Arches - Inhalt - Hypotheses.org · catenary vault is very common as its form gives...

Documents

Transcript of Building with Arches - Inhalt - Hypotheses.org · catenary vault is very common as its form gives...