Looking to build a 2-story residential home (3,200 sqft) in the next 1-2 years. The home will be a custom home and it will be near an earthquake fault area. I believe code wise it is a 2d zone but I would rather play it safe as the area has a potential for a 6.0 - 7.0 quake. So I would build it ABOVE what the code requires.

With that being said, Simpson makes some pretty cool ties to use on a wood structure to make it seismic resistant.

I've read that concrete structures are BAD for earthquake zones because they are heavy and wood is lighter and more forgiving than concrete would be.

How much testing has ICF undergone in regards to seismic zones and ICFs ability to resist major damage during a 6.0+ earthquake??

ICF's if built properly can withstand even the harshest of earthquakes, many years ago the University of Colorado did a simulation with ICF and a 10.0 earthquake...it survived the test.

I built many projects in Nor Cal, a couple right beside faults (the freeways are built on top of the major faults, i.e. 680 freeway). Do not assume you can build above what code requires, sometimes this is dangerous. A competent engineer will design the building and all connections to meet your seismic requirements.

There is such a thing as to much rebar in concrete construction. Those who think doubling or tripling rebar will be better can actually be making an error which could be catastrophic in some cases.

It's not so much ICF that has been tested, but reinforced concrete. There is a large body of knowledge on seismic engineering for concrete and steel composites.

All you have to do is ask your engineer. :-)

From the research I have done, there is not much in regards to ICF specifically, and how it will react in an earthquake.

When you ask the "wood builders" they will say that wood framed homes are better because they are lighter weight and allow for some movement. When you ask the "concrete builders" they will say that reinforced concrete is better because it's stronger and can take higher rack and shear loads.

Who to believe?

In a tornado or hurricane, the ICF home would be better but in an earthquake the jury is still out. Physics state, "The force of an earthquake on a building is directly related to its mass." An ICF 2-story home has A LOT more mass to it than a similar wood framed home.

According to Simpson, a 6-story wood frame building can take a 7.5 quake and come out basically intact:

http://youtu.be/9X-js9gXSME

Both wood and concrete are going to fail if not assembled properly

Posted By Chris Johnson on 18 Nov 2011 07:25 PM
Both wood and concrete are going to fail if not assembled properly

Failing is relative to what type of failure. It is a fact that when a concrete structure fails, people get crushed, injured and die. When a wood structure fails, there is less likelihood of getting crushed and buried alive. Just look at the recent quakes in Haiti, Christ Church, Turkey, etc., the concrete structures that failed caused the mass fatalities, not the wood structures. Not that having a wood framed structure falling on you is a fun thing to happen but I would rather have that happen then have a multi-ton concrete wall fall on me.

With both being equal (concrete and wood PROPERLY assembled), the question remains, which performs better in an earthquake?

What ICF has going AGAINST it, is its mass/weight and lack of flexibility. How does ICF overcome these issues in an earthquake?

From the research I have done, there is not much in regards to ICF specifically, and how it will react in an earthquake.

What makes you think that ICF construction should behave any differently from reinforced concrete?

Posted By Lbear on 18 Nov 2011 08:23 PM

What ICF has going AGAINST it, is its mass/weight and lack of flexibility. How does ICF overcome these issues in an earthquake?

Steel reinforcement, i.e. rebar.  The same as any other steel reinforced concrete wall.

Posted By ICFHybrid on 18 Nov 2011 08:52 PM

From the research I have done, there is not much in regards to ICF specifically, and how it will react in an earthquake.

What makes you think that ICF construction should behave any differently from reinforced concrete?

Most likely it would react the same, I just haven't seen any research on it using ICF specifically.

Posted By arkie6 on 18 Nov 2011 10:42 PM

Posted By Lbear on 18 Nov 2011 08:23 PM

What ICF has going AGAINST it, is its mass/weight and lack of flexibility. How does ICF overcome these issues in an earthquake?

Steel reinforcement, i.e. rebar.  The same as any other steel reinforced concrete wall.

I can see rebar providing concrete with strength to prevent it from cracking and falling apart but ICF still has the mass/weight issue which can't be overcome.

I would like to see a test where the put a 2-story ICF home on a shake table and see if it can take a 7.0 quake without catastrophic failure.

I work at a massive nuclear power plant that is designed to withstand the most extreme earthquake for this area and it is built of steel reinforced concrete, at least in the vital areas of the plant. Engineers know how to design concrete structures to withstand earthquakes.

I would like to see a test where the put a 2-story ICF home on a shake table and see if it can take a 7.0 quake without catastrophic failure.

Maybe if you Googled the visual documentation of shake table tests involving reinforced concrete buildings you would get a better feeling for the strength of concrete and steel composites. They might be more massive than wood frames, but the strength is many times that of the wood frame members and connections as well.

Not only do I live in an very high seismic design area, but my current residential project is specially engineered to survive seismic acceleration much higher than what you mentioned. Since it is an ICF/stick framed hybrid, that consists primarily of extra steel in the concrete and more Simpson connectors in the framed portion.

Upon dumping one of his loads, the steel yard truck driver said "Whew! I've never seen so much steel go in one place". A few months later, the lumberyard truck driver said essentially the same thing after having staggered into the house with multiple loads of Simpson connectors. Engineering can get you there in both cases.

http://www.bhrc.ac.ir/Portal/LinkClick.aspx?fileticket=mYzS9%2FRhYtk%3D&tabid=584

^^ Here is something to read, not that I read it all

Bottom line a concrete structure if built correctly is fine, but also catastrophic failures can happen anytime the conditions are right...no matter what the product

Also realize the countries you mentioned were the some of last to recognize the use of reinforced concrete. I was in Panama many years ago watching concrete being placed without rebar.

I built many projects in earthquake country, each was engineered individually based on it's area and proximity to fault lines.

Wood framed projects had shear panels, nailing patterns, hold downs, CS strapping tying the building together, etc, etc.

Ask an engineer as I did, ICF or reinforced concrete is much easier and faster to design and build in these situations, ICF or reinforced concrete is 100% sheer walls

Posted By ICFHybrid on 19 Nov 2011 08:34 AM

I would like to see a test where the put a 2-story ICF home on a shake table and see if it can take a 7.0 quake without catastrophic failure.

Maybe if you Googled the visual documentation of shake table tests involving reinforced concrete buildings you would get a better feeling for the strength of concrete and steel composites. They might be more massive than wood frames, but the strength is many times that of the wood frame members and connections as well.

Not only do I live in an very high seismic design area, but my current residential project is specially engineered to survive seismic acceleration much higher than what you mentioned. Since it is an ICF/stick framed hybrid, that consists primarily of extra steel in the concrete and more Simpson connectors in the framed portion.

Upon dumping one of his loads, the steel yard truck driver said "Whew! I've never seen so much steel go in one place". A few months later, the lumberyard truck driver said essentially the same thing after having staggered into the house with multiple loads of Simpson connectors. Engineering can get you there in both cases.

What is this "hybrid" build? Do you have a link to see what you are constructing?

Do you have a link to see what you are constructing?

I'm not that organized.

It's just a residence with ICF basement and first floor and stick framed second floor.

lbear....you might want to read some of these.


http://www.bing.com/search?q=icf+and+earthquake&qs=AS&sk=&pq=icf%2520and%2520earthqu&sp=1&sc=1-15&form=QBLH

If you look at high-rise construction in seismic zones worldwide as an example, you will find that the vast majority are reinforced concrete to withstand the loads from major seismic events. It's probably a function of cost in those structures. Obviously, for low-rise you can make both framed and ICF structures adequate for seismic events. Compare the costs - but then don't forget all the other benefits of ICFs (energy savings, health, comfort, noise reduction, fire-safety etc).

Chris,

You said:

"There is such a thing as to much rebar in concrete construction."

Can you give an example?

When engineering reinforced concrete, you want the steel to fail (just) before the concrete crumbles. The proper ratio is considered to be UNDER-REINFORCED, and is actually a desirable condition, despite the name. The alternative is OVER-REINFORCED, which you do not want.
Too much steel can actually prevent proper consolidation of the concrete.
Too much steel can get crowded to the outside where it can't get adequate cover and corrosion can be introduced into the assembly.
Since steel is about three times as dense as concrete, too much steel causes the assembly to become heavier than proper engineering indicates.

That's a bank vault! I've seen them made at Security Systems Equipment and there couldn't be any more rebar in the modular vault panels. Also highway barricades are also highly packed with rebar.