Current Research

UBC and BCIT have both teamed up with the SPEA to conduct cutting-edge research in seismic resistance of cob and living roofs, respectively.

A scale model of the SPEA building was constructed and tested at UBC on the hydraulic shake table. UBC Civil Engineering professors Dr. Carlos Ventura and Dr. Helmut Prion are analyzing the shake test data. A co-op student worked with the office of the chief building official for the City to coordinate this groundbreaking research, with the hopes of developing a natural building code.

As some of you may recall, we tested the model a few weeks ago unsuccessfully. The building received a massive pounding, but did not simulate an earthquake as it was supposed to, due to problems with the hydraulics. Despite the massive pounding, the building received only minor damage.

With the hydraulics repaired, we successfully conducted our tests on Sept. 20th. The model, which was about 6 ft diameter and 5 ft high, easily handled a 7.4 richter quake with only minor cracks. And this was after the previous pounding that certainly compromised the structure. This quake simulated a particular quake in California that was particularily destructive to buildings.

Finally, the building was given a 2 g force shake, something closer to a 9 richter and at the epicenter. As was expected the building was shaken apart. This would be a very rare quake and no building would easily survive this level of shaking forces. Amazingly, despite such a violent shake, the building remained standing, though large chunks of cob had fallen away from the building. Anyone inside would have survived as the roof remained in place and no large cob fell inward.

There was considerable rocking of the building from side to side which points to the importance of tying/keying in the building to the foundation well, although I expect that the failure would then be the mortar in the stone foundation. Another interesting observation was the amount of shearing, probably at horizontal layers that were not tied together so well. Embedding bamboo dowels or something like this throughout the walls would greatly reduce this type of failure. The engineers were very impressed by cob's performance and now have some good data and video footage to explore ways to increase cob's strength for those of us in earthquake zones.

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