Earthen buildings are strong in compression, but need help against tension or bending stresses. The barbed wire and vertical rebar in earthbag add important tensile strength.
More than 50 earthbag buildings in Nepal have recently survived 0.5- >0.7g of earthquake motion. This same motion destroyed poorly reinforced and unreinforced masonry buildings around them, mud block and brick alike.
But existing earthbag is not magic. Standard earthbag has its limits. Adobe reinforcements that have performed well in New Zealand’s >2 g seismic risk show us what earthbag needs.
Here are three new options for building stronger earthbag, including intermediate levels for Nepal’s 1g to 1.8 g risk areas.
Owen Geiger and Kelly Hart have been instrumental in developing these guidelines. We welcome more comments and help.
Type A is the standard earthbag method used in low risk zones. Because Nepal’s quake risks are for motion 1.5- 3 times as severe as that experienced in the recent quakes, we encourage builders in Nepal to consider adding some improvements to earthbag, like Type B or better.
Read the complete report Earthbag Options for Nepal online at http://buildsimple.org/resources/EB%20Options%20for%20Nepal.pdf
And see BSI’s simple visual building guides like Building EB Walls Better- we will be updating them soon, but can be found at http://www.buildsimple.org/earthbag.php – follow the link on upper left.
Special thanks to Patti Stouter at Build Simple.org for her remarkable efort making this report available. She must have squeezed in 100 or more extra hours into her schedule to pull this report together in such a timely manner.