Bamboo for Earthquake Reconstruction

I have just returned from Nepal where I attended the National Consultation Workshop on “Bamboo for Sustainable Post-Disaster Reconstruction in Nepal”. This is one of the activities in a CFC-funded project implemented by INBAR that aims to develop capacity for architects and builders in working with bamboo during the reconstruction after last year’s earthquake on 25 April.

The meeting was hosted by the International Centre for Integrated Mountain Development (ICIMOD), a fellow member of the Association of International Research and Development Centres for Agriculture (AIRCA).  We had a good turn-out with nearly 100 participants, and the meeting was opened by HE Agni Prasad Sapkota, Minister for Forests and Soil Conservation.

The presentations included recent experiences from two Nepali private sector companies: Himalayan Bamboo (www.himalayanbamboo.com) and abari (www.abari.org). They gave examples of building with bamboo, and stressed that a bamboo house does not have to look like a log cabin, but the final product can have the appearance of a “normal” residence. The following slide from Himalayan Bamboo makes the point:

cropped-presentation-HimalyanBamboo

Nepal already includes bamboo in its national building code and during the past 15 years, INBAR and its Government focal point the Department of Forest Research and Survey have developed a number of bamboo building systems that meet national and international building standards.

One of the recent success stories is that the Ministry of Education has approved a new design for schools from ABARI that includes bamboo to produce the roof trusses. This could help Nepal rebuild many of the 7000 schools destroyed during the earthquake, which was one of the serious effects of the 2015 earthquake. Unicef estimates that nearly 1 million children have been affected as so many classrooms were damaged or destroyed. This recent agreement to use bamboo in those areas where it grows in abundance is a major step forward to resolve the shortage of teaching facilities.

Nepal-school-design

After the presentations we had a lively discussion with the audience, with many technical design questions, comments about supply and demand, interactions about government policies and building guidelines and more. One of the participants informed us that the Department of Civil Engineering of the University of Kathmandu will include bamboo in its teaching syllabus.

One of the key messages during this discussion is that bamboo is not a “silver bullet” solution for all reconstruction efforts, and most buildings made with bamboo will have other materials in the construction as well. This point was emphasised during the afternoon visit to the building that houses Madan Puraskar Pustkalaya; the largest archive of Nepali literature.

MadanPuraskarPustakalaya-Kathmandu

The original building was badly damaged in the earthquake, and a decision was made to use bamboo as the main structural component in the new construction, and ABARI is taking care of the work. The main vertical supports of the building are made from round bamboo poles that are resting on metal blocks. The bamboo that is used is Bambusa Balcooa; the predominant species in Nepal .

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But, while the main structure is made from bamboo poles, the walls of the building are constructed from rammed earth. This is a process of building by adding layers of soil that re compacted under pressure, creating a solid wall that is as hard as concrete. Other walls will be made by covering wire mesh with concrete and lime.

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The most striking feature of the building is the roof structure, which is made from many intersection pieces of bamboo.  It looks amazing, and will be covered with normal roofing tiles.cropped-roof.jpg

One of the challenges of building with bamboo is how to fix two or more round poles together without cutting the poles. The solution promoted by ABARI is a system that comprises a small metal bar that is inserted across the bamboo poles, and a long screw that is attached to this metal bar and that protrudes beyond the end of the bamboo pole. The screw is then fastened in a metal bracket that holds several bamboo poles together. It is an innovative method that works well, and does not affect the strength of the bamboo poles.

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What intrigued me most was that apart from bamboo and rammed earth, the building also has some concrete beams to hold the first floor.

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This illustrates that a bamboo building does not have to be made of only bamboo, and ABARI stressed the point that a mix of building materials is the best solution. Their main recommendation is to make the roof trusses from bamboo in new construction, which is the best way to avoid future damage from earthquakes, as they bamboo poles will bend but not break!

 

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