by yesplease » Wed 21 Mar 2007, 17:32:01
Some earth bag construction has been approved for use, but CA's earthquake regulations may be lax. Using a Yurt or framed dome definitely seems like the best of both worlds, so long as the top of the earthen walls are reinforced with beams going across.
$this->bbcode_second_pass_quote('', 'S')uperadobe Technology, U.S. patent #5,934,027, has been tested on individual dome and vaults (1993-1996) for the City of Hesperia, California, Building and Safety Department, in consultation with I.C.B.O. These structures passed the California required codes.
$this->bbcode_second_pass_quote('Professor Membrane', ' ')Not now son, I'm making ... TOAST!
by tsakach » Wed 21 Mar 2007, 19:37:30
$this->bbcode_second_pass_quote('yesplease', 'S')ome earth bag construction has been approved for use, but CA's earthquake regulations may be lax. Using a Yurt or framed dome definitely seems like the best of both worlds, so long as the top of the earthen walls are reinforced with beams going across.
$this->bbcode_second_pass_quote('', 'S')uperadobe Technology, U.S. patent #5,934,027, has been tested on individual dome and vaults (1993-1996) for the City of Hesperia, California, Building and Safety Department, in consultation with I.C.B.O. These structures passed the California required codes.
Yes, I happen to have a copy of the complete engineering review process for this, where the City of Hesperia granted a building permit for superadobe. The permit approved by the City of Hesperia was for a non-residential structure, the Hesperia Lakes Nature Center and Museum. This structure was actually built and later bulldozed with the explaination given that shoddy construction was to blame.
During the review process, the engineer hired by CalEarth made the following statement regarding vertical ground movement:
$this->bbcode_second_pass_quote('', 'U')pward vertical motion in a seismic event will not create a problem. The mass of the structure reduces as we approach the top and the continuous wall provides a large amount of surface area to distribute any dynamic stresses induced by a vertical rising motion. Downward vertical motion in a seismic event should also not create a problem since the shear mass of the structure would make vertical seperation virtually impossible
That's it. There are no references or calculations to support the claims made by this engineer that "the shear mass of the structure would make vertical separation virtually impossible." In addition this statement was not challenged by the Hesperia building department. I would not want to bet the lives of my family and myself on unsupported statements such as this.
The structures were required to undergo dynamic load testing, where asymetric horizontal stresses were applied to the structure. These tests passed with no problems. However, no testing or simulations have been performed on these structures where vertical seismic motion is involved. This type of motion is present to varying degrees in almost all earthquakes. As a general rule vertical motion is defined to be 2/3 of the horizontal motion. But depending on characteristics specific to the site, such as terrain or soil, the vertical ground motion can actually be greater than the horizontal motion.
Other building departments are more cautious about granting approval for these structures. For instance, when submitting plans for a superadobe structure to the San Bernadino County building department, the following comment was received from the engineering review process:
$this->bbcode_second_pass_quote('', 'P')rovide positive connection between the sand bags and between each layer of sand bags per CBC section 161633.2.5. The bar wires between the bags are not approved connectors.