Primary School in a Village of Uttar Pradesh, India

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Primary School in a Village of Uttar Pradesh, India Laurent FOURNIER Architect-Gajadhar, TARUN BHARAT SANGH, Bheekampura-Kishori, Alwar, India

Laurent Fournier, born 1966, was granted the Romain Rolland Scholarship in 1993 to study the architectural heritage of Kolkata. Worked 5 years with Socotec (France), and received his architect degree from the Ecole d’Architecture de Paris-Belleville in 2003, with this school project. Now working for Tarun Bharat Sangh in water harvesting.

Summary This is an attempt to recover the quality and sustainability of ancient buildings, in today’s economic conditions of rural India. We describe the construction of a small building, part of a more comprehensive school project. Unlike ordinary contemporary constructions in the area, the building is comfortable without electricity, is more strong and durable, and by relying exclusively on local and traditional expertise and resources, it strives to restore the regard and repute they deserve. Keywords: masonry; arch; stone floors; natural comfort; traditional skill; cantilever; corbel.

1. Introduction The school is owned and managed by a family of the village, who invest in this project all their profit (coming from their tea stall in Kolkata). The project started in 2002 and the school opened in 2003. The first building with 4 class-rooms had been built by the masons under the supervision of the owner and the 5th class-room, a separate building, was built by me with 2 masons and 2 helpers, in 3 months. The building is much used when there is no class, for meetings, resting, etc. and the owner calls it “my glamorous building”. This is encouraging because besides the objectives of quality, sustainability, etc, it was sought after to make something that people would appreciate and value as their own. But the construction has revealed that this aim implies deeper questions, mentioned in the conclusion.

1.1. Wealth and Poverty A main problem of India is the growing difference of financial ability between the rural areas and the cities. A villager, even though his living conditions may be decent, will generally have to sell a disproportionate quantity of his own production if he wants anything from the city. Thus it makes sense to get the maximum out of local resources (materials, skills, traditions). But a more difficult problem arises; it is the extraordinary glamour that city products have for the villagers. Thus the development of local resources is also an aesthetic problem, because until the local people truly appreciate and value their real wealth and assets, and would not say anymore “stone is used by local poor people as a substitute for concrete”, but “every material has its proper use”, money will continue to flow from the poor to the rich. Therefore it is necessary, while harnessing local resources for economic reasons, to make things as beautiful and as extraordinary as possible.

1.2. Climate and Comfort It is not easy to work seriously, in village Bijauly during May and June afternoons. People are sheltered in the deepest parts of their houses for most of the day, all doors and shutters closed, fans and air coolers at full speed or, more likely, stirring frantically their hand fans due to power cuts. But one place is delightful: It is the mango garden, with its soft light falling from the high foliage of the trees, and its constant and gentle breeze, even when no movement of air is perceptible in the scorched fields outside.

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PRIMARY SCHOOL IN A VILLAGE OF UTTAR PRADESH, INDIA

In December and January, the weather is opposite but the result similar: As the sun hardly dissipates the fog, most people spend long hours cramped in their houses, doors and shutters closed to prevent the cold air to come in. But that time also, one place is enjoyable: The series of loggias built against the cliff beneath the Moghol city of Fatehpur Sikri, 90 km away, which provide a lukewarm atmosphere to the idle one who seats in the evening, contemplating the plain below. These two places show that it is possible to get a comfortable, natural and beautiful environment, and inspired the design of the building. Fig.1 outside view of the building

1.3. Local Ordinary Constructions Local people generally categorize their buildings into “kachha” (made of mud, bamboo, straw) and “pacca” (made of bricks, stones, wood, steel, concrete). The mud houses are nice to live in, but their maintenance is demanding. Nobody would maintain other people’s mud buildings against remuneration. The construction cost also would not be very low, if professionals did the work. Bijauly was a mud village 30 years ago, but today mud symbolizes poverty and is disregarded. So, one cannot seriously consider a mud school now. Broadly, the quality of the brick buildings follows their age: While many 150 years old structures (houses, temples, rest-rooms, etc.) are still in good condition, the quality witnesses a continuous fall until today. Most contemporary buildings have rainwater leakages, foundation settlements, disintegration of concrete, illogic structures, and a complete dependence on electricity for their comfort (while the power supply in this area is depleting as fast as the water). The immediate strength of cement, steel and concrete give the erroneous feeling that any structure will be strong, regardless of construction rules. In this evolution, elements like arches, vaults and cornices, materials like mud and lime, and common sense principles of natural light, ventilation and protection from water have faded; but some elements like the stone floors, have persisted.

2. Description of the Building The building, broadly a cube with three sides open, stands against the boundary wall (Fig.1,2). The lower part of the building is very open, with 11 doors separated by thick pillars, while the upper part, more close, has 11 brick “jali” (open-work), one above every door (Fig.1,4). The roof structure is made of 4 intersecting arches, of 4.50m span. This ancient Armenian design (Choisy [1]) has been chosen for its central symmetry, which allows a circular tie to Fig.2 Plan of the building

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counteract the horizontal thrust of the arches from outside the room. It is also very rigid and strong, because the 4 arches intersect each other thus allowing a very short buckling length. 8 pillars, connected 2 by 2 with smaller arches to neutralize the oblique thrust, support the 4 main arches. (Fig.2) The pillars are 1.60m high and the rise of the arches is 2.25m. The pillars are amply in equilibrium by the weight on them, but the circular tie has been provided in case of soil settlement etc. A secondary circular tie encircles the building at the roof level, and small partial ties are provided at the level of the jali. Apart from these ties and their anchorings, there is no steel or concrete in the building. Fig.3 cross-section (preliminary study)

The roof is a terrace, and is supported by the arches via a tympanum made of a brick jali, following a traditional design (Armenian churches, Muslim architecture, A.Gaudi, etc.). The tympanums confer a great rigidity to the arches (Fig.3,4). A wind-catcher will top the staircase (Fig.3). In summer, it will drive the wind through the stair-well down to a jali under the blackboard (Fig.4). The doors and shutters will be made of steel sheets nailed on wooden frames, and fixed directly to the masonry. In winter they will be close at night, and open on southern side in daytime. In summer they will be open at night, and close on southern side in daytime. Fig.4 inside view during construction

3. The Construction Process 3.1 The Vertical Structure The foundations are identical to the common constructions in the area: made of second class bricks with mud mortar, 3 feet deep, exerting a pressure on the soil inferior to 0.1 Mpa (Fig.3). The pillars are hollow, made of 2 leaves of 0.12m (one half-brick) joined by 3 “cross-walls”. Thick pillars soften the light and are stronger, and the hollow parts improve the insulation. We chose exposed brickwork, as recommended by Laurie Baker [2]. This is consistent with the endeavour for quality brickwork, and reduces the overall cost, though it increases the initial cost due to the necessity of a clean work. But it was not well accepted by the masons or by the villagers.

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Two stone slabs at the base and the top of the pillars improve the cohesion of the masonry, and finish the pillars cleanly (Fig. 5). The corbelled lintels are built without supports (Fig.5). The slope is 1:1 for aesthetic reasons, and the stability was precarious. When possible, a slope of 2:3, as recommended by Laurie Baker [2], would be easier to build.

Fig.5 construction of a corbelled lintel

3.4 The Arches 3.4.1 The Centerings In India centerings are generally made of brick jali assembled without mortar or with mud mortar. But here, having to build 4 identical arches at a big height, we chose to use a bamboo centering. We wanted to build the façade after the arches, to allow for adjustments. So the tympanums could not be built immediately, and the arches had to be stable under their own weight, i.e. have the shape of the ‘chainette’. The curve has been outlined on a wall at 1:1 scale with the help of a hanging rope, replicated on the ground with bricks, and the bamboo frame has been built inside this form.

Fig.6 Starting the first ring of a big arch (4.50m)

Fig. 7. making the second ring

For the big arches the bamboo centering involved more work than imagined: 2 days for 2 persons to build the frame, and 1 day for 4 persons to shift all the scaffoldings from under an arch to the next (Fig 6). As the repeated shifting increasingly damaged the bamboo frame, it had to be repaired regularly, the shape is not very accurate, and brickwork was slow. Also, the first ring had to be built first, with headers every 5 stretchers, in order to reduce the load (Fig 7). To build one arch took one full day. With brick centerings, the shape would have been better, and the 2 rings of each arch and the 4 arches would have been built simultaneously and more easily.

Fig. 8. one 1.20m span arch

Fig. 9. one jali-arch

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On the contrary, the bamboo centerings were very successful for small arches. Making one arch and shifting the centering to the next, took one day for 2.30m span, and one hour only for 1.20m span. 3.4.2 The Jali Arches The jali at the upper part of the facade is divided in 2 parts in 2 different planes order to allow a shutter rotating around a horizontal axis to be inserted between them. This mechanism is robust and will allow operating the shutters from the ground. The upper part has no support over a span of nearly 1m, so the whole jali is in the shape of an arch. Bricks centerings have been used, given the small height, the low rise, and the wish to get a perfect shape (Fig.9). 3.4.3 Calculating the Arches The 4 big arches have been checked with the formula: T =

w⋅l2 where T is the horizontal thrust, 8⋅r

w the load, l the span, and r the rise. With a live load of 400 daN/sq.m., the stress in the arches is 2m

0.7MPa, which is low, given a length of buckling of 2m, and a slenderness ratio of 0.25m = 8 The bricks for the big arches have been checked one by one. Only those that gave a clear and metallic sound under the hit of a hammer were selected (about 30%).

3.5 The Stone Chhaja (sunshade) Brick corbels, secured by the lower circular tie, support the sunshade. It is continuous around the building and projecting over 1m. It is similar structurally to a stone floor, but the slabs are sloping and overlapping like tiles on a roof. Comparatively to traditional chhaja, the slope has been diminished, and the system simplified. The main difficulty was to ensure self-equilibrium at every stage of the construction. (Fig.10) Fig. 10 building the sun-shade

The largest stones used are 1.45m x 0.60m, and weight about 70kg. The stones most exposed to shocks, in the upper layers, can be replaced easily. In the whole building, only red stone is exposed to rain, and cornices are projecting to avoid trickling of rainwater on the walls.

3.6 The Stone Roof 3.6.1 The Traditional Floor System and its Variations Nearly all floors in the area are, even today, built of red sand stone slabs, 0.03 to 0.04m thick, supported by steel joists spaced every 0.85m. There is no difference between a floor and a roof. The stone floors are always protected against thermal and mechanical shocks by a layer of bricks embedded in cement mortar. Until 20 years ago, lime-surkhi (brick-dust) was used instead of cement-sand, and it usually lasted more than 30 years, but now roofs often develop cracks and start to leak within 10 years. This can be explained by the ductility and insulating power of lime, especially when mixed with surkhi (Baker [2] and Khanna [3]). But now hydraulic lime is no more available in the area. We decided to insulate the roof with a mixture of mud+cow dung, protected by thin stone slabs. Khanna [3] describes this system.

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To reduce the weight, the traditional stone balconies are covered only by a thin cement plaster. Waterproofing is not a problem because rain is expelled quickly, but there is no mechanical protection. To improve the solidity, a “cantilevercorbel” system is used, by which the bending moment is significantly reduced by increasing the width of the supports (Fig.11). This system has been used widely in ancient stone architecture, for example in India, in many ancient temples Fig.11 a traditional balcony (particularly in the ceilings of the mandapa), in the Diwan-iam (hall of public audiences) of Agra and Delhi Red Forts, in many buildings of Fatehpur Sikri, etc. 3.6.2 Comparison of the Relative Strengths of Different Stone Floors Let us take the following notations (Fig.12): a = length of main stone A; b = length of supporting stone B; M1 = Bending Moment in the middle section of stone A; M2 = Bending Moment at the supports of stone A; M3 = Bending Moment in the middle section of stone B;

w = load per m. run;

We consider that the supports of the main stone A are near the edges of the stones B, because A being much longer than B its deflection and angle at this point are greater than those of B. a M3 M2

b M1 Fig.12 Bending Moments in a traditional balcony

We can write: ( a − b) 2 M1 = w ⋅ + M2 8 b b b2 M 2 = −w ⋅ ⋅ = −w ⋅ 2 4 8 a b a⋅b M 3 = −w ⋅ ⋅ = −w ⋅ 2 2 4 (1) + (2) gives:

M1 = w ⋅

(1) ( 2) (3)

a 2 − 2ab 4

( 4)

Assuming stones A and B have the same thickness, the optimum is reached when M1 = - M3, which gives from (4) + (3) : b = a / 4

(5)

2

In that case, M 1 = M 3 = w ⋅ a , which is half the moment in a single simply supported stone. 16

Further, the stone B is always a bit shorter than a / 4, so it cannot be broken by the stone A, which will break before. Thus the structure is safer, and sends “warnings” (cracks) before actual collapse.

Fig. 13 the corbelled support

The structure is further improved by equating M1 and M2. This implies M3 > M1, so the stone B has to be thicker than the stone A, or replaced by several layers of corbelled stones, as in our building (Fig. 13). Assuming M1 = - M2 we get: from (1) : w (a − b) + M 2 = − M 2 2

(7)

8

(7) + (2) gives: Fig. 14 the support seen from below

b=

a 1+ 2

(8)

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b2 With this ratio, M1 = w ⋅ 8

= w⋅

8⋅

(

a2

(9)

)

2 +1

2

Comparatively with a single simply supported stone of the same strength, this multiplies the span by 2.41

)

)

2 + 1) and

2

2 + 1 . Let us calculate M3 : 2 2 −1 w a ⋅ 2 2 −1 a⋅b 2 From (3) : M 3 = w =w⋅a = 8 4 4

the load by 5.82

Fig. 15 laying a big stone

(

(

(

))

Let us compare M3 and M1: M3 = 2⋅ M1

(

)(

2 −1 ⋅

)

2

2 + 1 = 2 + 2 2 ≅ 4.83

(10)

This ratio means we need 5 corbelled stones. But considering the width of the support, we can have fewer stones. In our case, the length of the main stone A is: a = 1.60m. So from (8) the length of the uppermost stone B is: b = 0.662m. Fig.16 the roof seen from below

The value

0.662m = 0.137m is twice the permissible lever 4.83

arm for every successive layer of stones B. By repeatedly subtracting this value we get the successive sizes of the corbelled stones: 0.662m; 0.525m; 0.387m; 0.25m (one brick); 0.113m (~1/2 brick, width of the supporting ~ tympanum). The corbelled stones have been laid overlapping, as in a wall. So the system has some of the ductility, hyperstaticity and safety of masonry. The central part of the terrace is 2 Fig.17 the terrace feet higher than the periphery. This ancient design combines an open view while sitting, with the safety of a railing. The solidity of the railing is ensured by many cross-walls and by 2 layers of overlapping heavy stones. 3.6.3 Assessing the Strength of the Terrace We can compare our floor, 1) with other floors of the village, or 2) with Indian Standards. 1) Comparing with a common floor of the village (single simply supported stone) the span has been multiplied by 1.60m = 1.88 , but we see from (9) that our system allows a span 0.85m

 2.41   = 1.64  1.88 

times greater. So the load bearing capacity is 

(

)

2 + 1 = 2.41

2

times greater.

With a realistic safe bending stress of 1.1Mpa, and given a minimum thickness of 4.5cm, (the stones were thicker than usual due to their large size) we get from (9) a maximum allowable load of 675daN / m2. The dead load is about 250daN/m2, which leaves a live load of 425 daN/ m2. This meets the Indian Standards requirements for school floors, 250 to 400 daN/m2 (Khanna [3]).

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4. Conclusion The room is the only one of the school without electricity and without ceiling fans, but it is also the only one where people can sit comfortably in summer. The breeze one feels in this room, even when there is no noticeable wind outside, may be due to the complete openness of the lower part of the building, combined with the relatively greater opacity of the upper part, which like the trees of the mango garden, pushes a part of the wind downwards. There is plenty of light even in the winter mornings, when the other rooms look bleak and cold. These results have been obtained though the roof insulation and the shutters are yet to be made. 4.1. Cost and Economy The price (70,000Rs, with 45,000Rs. of labour and 25,000Rs. of material) is higher than expected, but similar to that of the other rooms of the school if one takes into account the additional facilities: the large continuous sunshade, the staircase, and the usable roof with a security railing. The ratio between labour and materials expenses is the inverse of ordinary buildings, and nearly all the money has remained in the village and its surroundings. Where a steel joist would have cost 1500Rs. of steel and 30Rs. of labour (transporting and handling cost), the four 4.50m arches have cost 4000Rs. of work (2 days for making the centering, and 2 days for each arch, at 400Rs. per day) and less than 2000Rs. of materials. 4.2. Proficiency and Skill It took sometime before the masons could retrieve some of the quality required by this kind of structure, and making the hollow pillars in exposed brickwork was a good training for the more intricate construction of the stone chhaja and the arches. But their skill and cleverness improved so visibly during this 3 months construction, it was like the liberation of a dormant capacity, and there is no reason why they could not improve more if given the opportunity. There is still a long way to go, before we get to the level of the past or to the level of Laurie Baker and his masons… 4.3 Deficiencies of the Project - No plaster: additional initial cost, shrinkage of the inhabitant’s control over his building, and impossibility to perform the annual white-wash (lime painting at the occasion of Diwaly); - Difficult to repeat without an architect or an engineer or highly skilled masons; The design of the project is not irrelevant, but the design process (an architect who offers a finished design) is more problematic. The issue is not to make a perfect design but to make a project whose successes and shortcomings are consciously shouldered by the community, who may thus be able to learn from them. This project is a call in this direction.

5. References [1]

CHOISY A., Histoire de l’Architecture, Intereditions, Paris, 1989 (Fac-Simile edition of the XIX century original) 300pp.

[2]

BAKER L., Houses, How to Reduce Building Costs, COSTFORD, Thrissur, 1993, 50pp.

[3]

KHANNA P.N., Indian Practical Civil Engineer’s Handbook, Engineer’s Publishers, New Delhi, 1953-2001, 350pp.

[4]

FREDET J., CHARUE B., TAUPIN J.L., Guide du Diagnostic des Structures, ANAH, Paris, 1984, 400pp.