2.2 Ahmedabad as a world heritage city

4. Symmetrical structures (in both the directions) perform better during an earthquake, as an asymmetric structure would experience torsion10 5. Simple rectangular shapes in plan behave better than the one with many projections. 6. The building should be constructed using good quality of materials. 7. When the built structures are adjacent to each other there should be a gap between the two blocks like an expansion11 joint to avoid the hammering12 action. If the gap is not there, there can be a filling of weak material. 8. An earthquake responsive structure should be simple in terms of least compromise on structural integrity. The decoration should not hinder the main crucial joinery responsible for earthquake resistance. 9. Horizontal reinforcement is required in the walls to transfer the out of plane forces to the shear walls, else the walls can suffer from collapse. 10. Extra support must be provided to the main beams or columns, which will be responsible for the complete collapse in case of an earthquake.

2.2 Ahmedabad as a world heritage city

Ahmedabad – “Ahmed” – “Aabad”, a bustling busy city today was founded by the Sultanate ruler Ahmed Shah, in the year 1411. The city is located on the banks of river Sabarmati. Ahmedabad's old city is a walled city with its unique urban settlement and architectural styles. The city got its title of UNESCO World Heritage City in the year 2017. It is the first world heritage city in India. The settlement and self-sufficient house form were one of the most important criteria for the world heritage city nomination. The following is the criteria (v) description from the outstanding universal value document of UNESCO –

“Criterion (v): Ahmadabad city’s settlement planning in a hierarchy of living environment, with streets as also community spaces, is representative of the local wisdom and sense of strong community bondage. The house is a self-sufficient unit with its own provisions for water, sanitation, and climatic control (the courtyard as the focus). Its image and its conception with religious symbolism expressed through wood

10 Torsion – Twisting due to applied forces 11 Expansion joint – or movement joint that allows the contraction and expansion of the building materials, also allows the structure to move. 12 Hammering action – due to non-availability of adequate space between the buildings, they tend to collide with each other during an earthquake, that action is termed as hammering action (or pounding).

carving and canonical bearings is an ingenious example of habitat. This, when adopted by the community as an acceptable agreeable form, generated an entire settlement pattern with community needs expressed in its public spaces at the settlement level and composed the self-sufficient gated street “pol”. Thus, Ahmadabad’s settlement patterns of neighboring close-packed pol provide an outstanding example of human habitation.”

These pol houses with their unique timber and masonry construction typology were sufficient to put a historic city on the world map as a world heritage city.

The nomination dossier highlights the evolution of the Ahmedabad city from 1411 AD, Figure 8 suggests the settlement chronology within the walled city. The narrow lanes and settlement clusters, pols, which are formed through linear arrangement of houses, commonly termed as pol houses. The evolution study suggests that these pol houses are an integral part of the world heritage city. The unique typology and the settlement pattern are the identifying feature for the old city of Ahmedabad, hence the research’s rationale for addressing the seismic resilience of pol houses is crucial for the world heritage city status.

Figure 7 Evolution of Historic city of Ahmedabad, Source - (UNESCO, 2016)

With in the pol settlement, pol houses constructed during different times and styles. (2020) Entrance to chaumukhji ni pol. (Author 2020) Pol lane – (2002)

Old vacant pol house with traditional todla door and timber lacing. (Author 2020) Exquisite wooden carving on front façade, second floor constructed in R.C. (Author 2020) Elaborate carved brackets are a unique feature for Ahmedabad pol houses. (Author 2020)

Entrance of Shantinath ni pol with the chabutra – the bird feeder, (NIDM, 2011) Pol house in Doshivada ni pol (Anushka Mital,2020)

Figure 8 Pol houses in Ahmedabad, source - varied