<div dir="ltr">Bob--<br><br>imagining the Oklahoma version of "The Big One," I think the gravest danger is the collapse of the brick foundation walls. in our region,bricks from the 20's can be pretty soft, and the mortar can be powdery.<div><br></div><div>if that all describes the scenario, simply anchoring the floor system to the top of the brick walls might be inadequate. the strength of the foundation walls would be limited to the compressive force exerted by the weight of the house above. in this sense, the weight of the brick veneer is your friend--but I think the veneer is going to be the first element to fail when things start to shake. The point being, that even if the floor is anchored, the foundation walls could rotate in, between corners. </div><div><br></div><div>one could of course jack up the house and install a new reinforced cmu or poured concrete foundation beneath it. Or form up and pour new walls against the existing walls.<br><br>but less intrusively, one might strengthen the walls by increasing the compressive force--perhaps by excavating and installing a set of pier footings at intervals around the basement perimeter, each pier footing undermining the existing footing--maybe 2' wide or so. each pier would have a reinforced anchor bolt, to fasten some set of threaded rods and turnbuckles--which in turn would be bolted to the floor joists. Ideally, there would be two rods for each pier footing, run diagonally in opposite directions, parallel to the foundation walls. <br><br>There a lot of boggling variables here--such as the moisture content and plasticity of the soil, height of backfill, direction of seismic waves--so sizing the footings and rods, and determining how many to install would be speculative. Maybe a big shaker would overcome this effort. Or maybe it would hold up long enough for you to escape before it all comes down. I don't envy your situation.</div><div><br></div><div>-aa<br><br><br></div></div><div class="gmail_extra"><br clear="all"><div><div class="gmail_signature"><div dir="ltr"><div><div dir="ltr"><font size="2"><font size="2"><span style="color:rgb(102,0,0)">Alan Abrams</span></font><b style="color:rgb(102,0,0)"><br></b><i><span style="color:rgb(102,102,102)">certified professional building designer, AIBD<br>certified passive house consultant, PHIUS</span></i></font><div><i><span style="color:rgb(102,102,102)">certified passive house builder, PHIUS</span></i><font size="2"><span style="color:rgb(102,0,0)"><font color="#666666"><i><br></i></font></span></font><font style="color:rgb(102,102,102)" size="1"><font size="2">cell </font></font><font style="color:rgb(102,102,102)" size="1"><font size="2">202-437-8583</font></font><font style="color:rgb(102,102,102)" size="1"><font size="2"><br>
<a style="color:rgb(102,102,102)" href="mailto:alan@abramsdesignbuild.com" target="_blank">alan@abramsdesignbuild.com</a><br style="color:rgb(102,102,102)"></font></font><a href="http://www.heliconworks.com/index2.html" target="_blank">HELICON WORKS <i>Architecture and Education</i></a></div></div></div></div></div></div>
<br><div class="gmail_quote">On Tue, Mar 29, 2016 at 11:05 PM, ErgoDesk <span dir="ltr"><<a href="mailto:ergodesk@gmail.com" target="_blank">ergodesk@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div class="gmail_default" style="font-family:arial narrow,sans-serif;font-size:small">California... I would reinforce your FIRE Insurance first.</div></div><div class="gmail_extra"><br clear="all"><div><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><span style="color:rgb(51,51,51);font-family:proxima-nova-1,proxima-nova-2,Tahoma,Helvetica,Verdana,sans-serif;font-size:14px;line-height:21px">Sincerely,</span><br style="color:rgb(51,51,51);font-family:proxima-nova-1,proxima-nova-2,Tahoma,Helvetica,Verdana,sans-serif;font-size:14px;line-height:21px"><span style="color:rgb(51,51,51);font-family:proxima-nova-1,proxima-nova-2,Tahoma,Helvetica,Verdana,sans-serif;font-size:14px;line-height:21px">George Hawirko</span><font color="#0000ee" size="2"><u><br></u></font></div><div><font color="#0000ee" size="1"><u><a href="http://about.me/StyroHome" target="_blank">http://about.me/StyroHome</a></u></font><br></div><div><font color="#0000ee" size="2"><img src="https://docs.google.com/uc?export=download&id=0B-dHkb_CdyxzV0tCYlkxcWdaOGM&revid=0B-dHkb_CdyxzOGFzdFhvVmNXc012RFVRTFQzM2hyUjhJS2V3PQ" width="200" height="150"><br></font></div></div></div></div></div></div></div></div></div></div></div></div>
<br><div class="gmail_quote">On Tue, Mar 29, 2016 at 11:40 AM, Jason Holstine <span dir="ltr"><<a href="mailto:jason@amicusgreen.com" target="_blank">jason@amicusgreen.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div>
<font face="Calibri, Verdana, Helvetica, Arial"><span style="font-size:11pt"><br>
I think you can find retrofit resources online from California. I think their state emergency mgmt agency, state NAHB, etc. have docs. It could become a nice side biz tightening up Okie corrals.<div><div><br>
<br>
<br>
On 3/29/16 1:41 PM, "Bob Waldrop" <<a href="http://bwaldrop1952@att.net" target="_blank">bwaldrop1952@att.net</a>> wrote:<br>
<br>
<font color="#0000FF">> So here in central Oklahoma, we have been experiencing a growing series <br>
> of earthquakes over the last few years. The USGS just released a map <br>
> showing the risk of human-induced earthquakes, and Okie City is right <br>
> there. The news said we were at perhaps a 10% risk of a level 6 <br>
> earthquake. Most of the thus far have been in the 2 to 4 range.<br>
> <br>
> Now we are not only tornado alley, but also earthquake central, more <br>
> earthquakes last year even than California had.<br>
> <br>
> I lived in the Bay Area of California and in SLC (on top of the actual <br>
> wasatch fault a geologist friend told me), and never experienced a <br>
> quake, but I've felt several here. I've also been watching the cracks <br>
> in the interior plaster/lathe walls and my exterior brick veneer develop <br>
> and progress.<br>
> <br>
> I do have earthquake insurance, but it is really only good for a <br>
> complete catastrophe. It has a 10% deductible, and it doesn't cover <br>
> masonry.<br>
> <br>
> The house has always seemed very sturdy. It was built in 1929, the <br>
> studs are on 12 to 14 inch centers and are a hard wood. THe sheathing <br>
> is 1 x 8 planks. Then there is brick veneer over that. The foundation <br>
> is brick. The back and front porch construction seems separate from the <br>
> rest of the house. The concrete front porch is certainly pulling away <br>
> from the rest of the house over the 16 years I've lived here.<br>
> <br>
> Any thoughts about retrofits that would strengthen the house in the face <br>
> of the growing earthquake risk here?<br>
> <br>
> Bob Waldrop, Okie and Shaky City<br>
> <br>
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