Earthquakes early last year caused severe damages to residential buildings. Up to 80 percent buildings were either partially or completely damaged in rural areas. Most of these buildings were traditionally constructed, using local materials like adobe, stones and wood. Generally, building structures in affected areas were made of sun dried brick and undressed stones, and bonded with mud mortar. They suffered damages primarily because of this low-strength mortar. The masonry in these buildings was unreinforced and the walls were not tied to each other or to the floors and roofs. So how come many traditionally constructed buildings are still intact?
Reinforced cement concrete (RCC) buildings are the most common type of construction in urban areas including Kathmandu. But RCC buildings, which were perceived to be strong in comparison with traditional structures, turned out to be of poor quality. Even in Kathmandu Valley, it was found that many of these buildings did not even follow basic structural principles. Thousands of RCC building including multi-storied apartments, schools, hospitals and public buildings were thus badly damaged.
Most structures—whether ‘modern’ RCC buildings or ‘traditional’ ones—suffered enormous damages, causing a massive loss of life and property. Lack of adequate knowledge and poor workmanship were the main reasons for such extensive damage. Modern building methods do not automatically offer safety. In recent earthquakes in Turkey (1999), India (2001), Pakistan (2005) and Nepal (2015) a large proportion of RCC buildings collapsed and cracked, while some of traditional buildings suffered minimal damage.
The government of Nepal has proposed 17 different residential building models for post-quake reconstruction. According to government record, 800,000 houses have collapsed; over 80 percent of them had mud mortar. But the government-proposed houses are small, not even enough for a nuclear family. It has also not proposed a model for cattle shade (barn) which is important in term of livelihood in rural areas. Husbandry and agriculture have been also neglected.
Government of Nepal has announced Rs 200,000 as compensation (per household) to build earthquake resistant houses. The house owner must adopt one building model out of 17 to get the relief fund to build their home. Even if house owner chooses a cheap building model, it will cost no less than Rs 500,000. For some building models that have been proposed, Rs 200,000 is not even enough for foundation work. The house owner has to spend one or two more lakhs to build the cattle shade.
A large proportion of the population is economically disadvantaged. They do not have access to nor can afford modern construction materials such as cement and steel. Further, the transportation cost is high. The National Reconstruction Authority (NRA) focuses too little on traditional technologies and too much on cement-based mortar and steel reinforcement. These, again, are not feasible options.
Poor people are inevitably tempted to use inferior materials and cut corners to meet NRA design specifications. Its models are, in fact, culturally and climatically incompatible and economically unaffordable.
The inability to consider local cultural needs has led to problems in recovery. Negligence of special requirements in reconstruction has led to dissatisfaction and uncertainty. In other words, architecture and interior designs of reconstructed houses did not meet the needs of people in quake-stricken areas. In many cases the new structures are just makeshift shelters and are devoid of space to store agriculture products.
The use of traditional construction systems, skills and material is desirable. Such systems are developed locally under local control and low use of technology. This allows for better maintenance and greater sustainability, as well as enabling incremental upgrading and expansion.
The use of traditional techniques also allows for the involvement of owners and local people in construction, thus mobilizing local economic resources.
At the same time, procuring construction material, often in significant quantities, can inflate prices to prohibitive levels. Local markets cannot always cope with increased demand and stocks may get depleted. Instead recycled material such as wood and slate from damaged settlements may be used so long as it is culturally acceptable to do so. The structures built using local building techniques (timber frame with masonry infill and timber laced bearing wall) also perform better than many poorly built ‘modern’ structures. People can get this wood from their own community forest.
In the proposed building models, in most instances, traditional constructions, which had in fact performed better against the earthquakes, were abandoned both by government and house owners due to a prevalent perception that traditional buildings are not strong. Many case studies prove that this perception is wrong.
Using cheap and environmentally friendly building materials like bamboo, wood, straw, and rammed earth in reconstruction can solve issues of safety, environment and cost. NRA guidelines favor the use of new materials like cement while overlooking the traditional mud, which was perceived as ‘weak’ and ‘outdated’. Similarly, straw bales can be used as basis for walls. It provides excellent insulation and is energy efficient. It is easy to make and is cheap.
Some construction specifications are not feasible in hilly areas owing to unavailability of resources. A simple example is curing of mortar or concrete, which is virtually impossible in many remote areas where there is not even enough water to drink.
What is happening is that new materials such as brick and concrete are being combined randomly with traditional materials such as stone and wood, thereby adversely affecting their structural integrity and seismic performance. With new material and technology, traditional masons found themselves incapable of using their old skills. Trainings are not provided to local masons to upgrade their skill and make them familiar with modern construction.
We must protect cultural heritage even in post disaster situation. Cultural heritage also helps promote tourism like home stay in hilly areas which is directly linked with livelihoods of the people, a prime factor in reconstruction.
A core housing design should be agreed, which could then be adapted to specific household requirements, reflecting their income, available building materials, land features and specific site conditions. Individual designs have to be then drawn in consultation with beneficiary families.
Moreover, the NRA should have a program to engage research institutes like the Institute of Engineering (IOE) to improve the traditional materials and designs, if at all possible.
The author is a PhD candidate in civil engineering at University of Alberta, Canada
keshab@ualberta.ca
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