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<TITLE>Re: [GSBN] PAKSBAB Straw Bale House Shake Table Tests - March 27, 2009 - A Great Success!</TITLE>
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<FONT FACE="Arial"><SPAN STYLE='font-size:12.0px'>Everyone, <BR>
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I’ll add a few things to Darcey’s initial report about the PAKSBAB shake table tests.<BR>
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The tests in the range of 1.50 to 2.00 times the Northridge earthquake were quite dramatic. There was significant movement of the building (relative to the table) and increasing damage to the plaster (new cracks, crack enlargement, delamination of plaster in places) as the forces were increased with each test. But the building as a whole did very well, and even at twice the Northridge quake, did not “fail” in the sense that there was no structural failure. It’s difficult to predict at what force it would have suffered a collapse or failure of one or more structural elements.<BR>
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I’m not sure how it was decided to stop at twice the Northridge quake, but I do think it was an appropriate stopping point. If for no other reason, it allows repair of the building (by replacing damaged plaster) and retesting it to see how it will fare after being repaired. This is very valuable information, and there is a tentative plan to do so.<BR>
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The last test did make many people nervous that another step might topple a wall. This included the University professors who oversee the lab and its testing. On a visceral level I was in that camp, but I suspect that was due to the system’s ability to move as much as it did (laterally and uplift), but then come back to it’s original place (more or less centered on the foundation). So it looked like it might begin to fail, but then it rescued itself.<BR>
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The wall system includes nylon fishing net reinforcement that wraps under the foundation and is embedded in the soil cement that encapsulates the gravel bag foundation, continues and is embedded in the clay plaster on the bales, and is attached to the lumber top plates. In the last few tests the nylon net stretched and deformed in a few places at the foundation, but it generally seemed to allow only so much drift and then pulled the wall system back to a stable position. There was little or no failure at the connection of the net to the top plate, nor at the connection of the light corrugated steel roof to the top plates. The opposing bamboo pins, engaging the foundation and the top plates, seemed to perform well in resisting the out-of-plane forces in a flexible manner.<BR>
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Because there was no evidence of failure of the nylon net or bamboo, I believe the building could withstand significantly greater forces and still remain safe (that is, not collapse). But the threshold we stopped at is already a fairly high one, and we’re very happy with the building’s performance. <BR>
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The ground acceleration numbers Darcey gave (see below) are the best measure I currently know for comparing the shake table movement and forces to historical earthquakes. I need to better understand earthquake metrics (especially the logarithmic Richter scale and how it relates to ground acceleration, total energy, etc) and all the other factors involved before I say more on this subject. I’m sure Darcey will have a good summary about this in the future.<BR>
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I don’t want to start an exhaustive dialogue about the tests at this time. Darcey is certainly the primary person to present findings from the test and I know she is preparing to leave for Pakistan, so she has little time now to properly do so. But I wanted to add my initial observations that I thought some might be interested in.<BR>
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I also want to acknowledge Darcey’s diligent and tireless effort (with help from many others) in shepherding and being the driving force behind this very successful testing project.<BR>
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Martin Hammer<BR>
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On 4/2/09 12:21 AM, "Darcey Donovan" <ecoengineering@gmail.com> wrote:<BR>
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</SPAN></FONT><BLOCKQUOTE><FONT FACE="Arial"><SPAN STYLE='font-size:12.0px'>Dear GSBN friends,<BR>
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I'm pleased to report that our straw bale house performed exceptionally well during the shake table tests at the University of Nevada, Reno, last Friday. The input motion was the Canoga Park Topanga Canyon record of the 1994 Northridge, California earthquake, Mw 6.7. The house was subjected to increasing levels of seismic shaking, beginning at 25% of the recorded ground acceleration and increasing at 25% increments until failure. The house survived 0.82g (0.82 times the acceleration of gravity), twice the acceleration of the Canoga Park record. The Geological Survey of Pakistan estimates the 2005 Kashmir earthquake, Mw 7.6, to have had peak ground accelerations in the range of 0.3 to 0.6g. <BR>
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I am extremely grateful to EERI, NEES and UNR for their generous support, and to all the hardworking volunteers who dedicated countless hours to this project.<BR>
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To view the abstract and download a handout please go to <FONT COLOR="#1F497D"><a href="http://nees.unr.edu/projects/straw_bale_house.html">http://nees..unr.edu/projects/straw_bale_house.html</a></FONT>. See<FONT COLOR="#1F497D"> </FONT><a href="http://www.kolotv.com/home/headlines/42035847.html#">http://www.kolotv.com/home/headlines/42035847.html#</a> <a href="http://www..kolotv.com/home/headlines/42035847.html"><http://www.kolotv.com/home/headlines/42035847.html></a> for publicity we’ve received regarding the test. </SPAN><FONT SIZE="4"><SPAN STYLE='font-size:13.0px'>For more information about PAKSBAB please visit www.paksbab.org <http://www.paksbab.org/> .<BR>
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More videos and test report to come…<BR>
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Kind regards,<BR>
<BR>
Darcey<BR>
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</SPAN><FONT SIZE="4"><SPAN STYLE='font-size:13.0px'><BR>
Darcey Donovan, P.E., C.E.O.<BR>
Pakistan Straw Bale and Appropriate Building (PAKSBAB)<BR>
P.O. Box 1083<BR>
Truckee, CA 96160 USA<BR>
(530) 902-5516 cell<BR>
(530) 582-4965 fax<BR>
0344-9455664 PAK<BR>
ecoengineering@gmail.com</SPAN></FONT><SPAN STYLE='font-size:12.0px'> <a href="mailto:ecoengr@sbcglobal.net"><mailto:ecoengr@sbcglobal.net></a> <BR>
</SPAN><FONT SIZE="4"><SPAN STYLE='font-size:13.0px'>www.paksbab.org</SPAN></FONT><SPAN STYLE='font-size:12.0px'> <http://www.paksbab.org/> <BR>
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