[Cob] cob model stands up to massive earthquake

[Ian Marcuse]

Hello all,

An exciting day was had by many yesterday at the University of 
British Columbia siesmic testing lab. As part of a collaborative 
project here in Vancouver with the City of Vancouver and the 
University, we have built a small cob model (6ft diameter) that was 
tested on the siesmic shake table in the engineering school. Built by 
Steve lay and others, the siesmic test is part of a more 
comprehensive materials testing that will help inform building 
officials here and further cob code and standards development in 
Vancouver. We have been working with senior building engineers and 
code developers here in the city.

Yesterday, our model was put to the siesmic test. The intent was to 
subject the model to a large earthquake (7.4 richter) that was 
recorded in the Mojave Desert, beginning at 1/4 intensity, then 1/2, 
and finally full
strength, recording failure after each test.  The first test started well.
However, technical difficulties with the shake table hydraulics resulted in
the table repeatedly contacting the bumper pads, delivering massive shocks
and subjecting the model to excessive forces.

The model however took it all in stride.  The building separated from the table
surface, but stayed intact.  After repeated shocks, only minor cracking of
the plaster was observed around window and door frames, with one crack
visible on the interior.

As reprted in the local newspaper next day, Helmut Prion, associate 
professor in design engineering said "We're getting desperate here to 
get this building destroyed. It just does not want to fall apart". 
Vancouver's chief building officer said the model looked like a good 
bet should a quake hit.

Although different than the forces experienced during an earthquake, the
ground acceleration was off the scale.  Thus, despite the table malfunction,
much was learned from the test.

Repairs are being made to the table, after which another attempt at the
actual tests will be made sometime next week.  Although already 
damaged, the model is expected to perform well.

Photos of the test will be uploaded to the photo diary over the weekend.
The diary is accessible at www.stanleyparkcob.ca by clicking the "Project
Diary" link on the left. We also plan to upload video footage soon.

Ian Marcuse
www.stanleyparkcob.ca
www.alternatives.com/cob-building