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RE: Earthquake-Proof Design

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Don,

I think what some are trying to say is that nothing is "earthquake proof" just different ways of achieving "earthquake resistance".  If you are doing just a "code design" then anything allowed by the code will achieve a "life safety" seismic performance level no matter what material or structural system you choose.  It is probably more a matter of economics and how complex a system you want to use.  For high seismic areas the code prohibits certain structural systems or only allows them to a certain height limit.

Plywood/stud shearwalls have performed very well for one and two story structures.  If you want a brute force resistance system you could go with 12 inch thick concrete shear walls.  If you are looking at steel, a special concentric braced frame would do nicely but so would a buckling restrained bracing system.  No reason you could not go with a base isolation system but you can imagine the cost and time of engineering not to mention the cost and time of construction and supply of materials.

From a layout standpoint you want as square, symmetrical, and boxy a structure as possible.  Just go through the code "irregularity" section and make sure you do not have any.

Thomas Hunt, S.E.
Fluor



"Donald Bruckman" <bruckmandesign(--nospam--at)verizon.net>
11/02/2007 10:22 AM
Please respond to seaint
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RE: Earthquake-Proof Design





I am, but I’m not an idiot, even if I did (literally) stay in a Holiday Inn Express last night.  <g>
 
Anyway, see, now I already have a vote from Bob for steel braced frames and a dynamic analysis.  
Do I have any takers for concrete?   Too rigid?  
How about more rigid masonry shear walls with wood diaphragms.
 
 



From: Neil Moore [mailto:nma(--nospam--at)omsoft.com]
Sent:
Friday, November 02, 2007 9:50 AM
To:
seaint(--nospam--at)seaint.org
Subject:
RE: Earthquake-Proof Design

 
Sorry.   I kind of guessed that you might be an architect.

Neil



At 09:39 AM 11/2/2007, you wrote:

Gee whiz….really? What a great idea…..Why didn’t I think of that?
Thanks for the input Neil….Unfortunately, that would give me exactly ONE opinion and as much as I respect the engineer I generally use, that wasn’t the point of the post.  I wanted to get a discussion going about more general strategies.  I guess we could just go back to the bio-diesel discussion if you’d prefer...

-DB  



From: Neil Moore [ mailto:nma(--nospam--at)omsoft.com]
Sent:
Friday, November 02, 2007 8:59 AM
To:
seaint(--nospam--at)seaint.org
Subject:
Re: Earthquake-Proof Design


Hire a local structural engineer and a local geologist.

Neil Moore, SE, SECB



At 08:52 AM 11/2/2007, you wrote:

Listen, you clowns…I leave town for one day and come back to 93 messages about just about everything BUT engineering.  So, either I start a thread lambasting Prof. Astenah’s cheesy, stinkin’ football team and how we Trojans will be up there soon to kick Bear, OR I will start a new thread about EQ design.

I’ll start with that and see if it morphs into a football board.

I have a client that bought a piece of land in North LA County.  I’ve been to the site and it’s a really pretty, sort of bucolic little area full of chaparral and butterflies.  Unfortunately, it also has, about a 3 wood away, the grinding fury of two continental tectonic plates sliding by each other. I think they call it The San Andreas Fault.

So, after the preliminary discussion wherein I say, “There is no such thing as an earthquake-proof building…blah blah blah…”, we got serious and he and I agreed that I would try to get as close as I could by affecting the design in such a way that the threat could be minimized.

So, with that in mind, I told him, for instance:  Tall building?   Not so much….Irregular building with re-entrant corners….not so much….Now, more broadly, the question for the board:

What are the other various strategies that would minimize the risk?

--DB



 
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