7-Story Wooden Condo Survives 7.5 Magnitude Quake 146
Mike writes "Earthquake news abounds as of late — recently a team of researchers from five universities unveiled an seven-story earthquake-proof wooden building that is capable of withstanding severe earthquakes. Featuring a structurally efficient nail distribution and a 63 anchor tie down system, the wooden condominium survived a test using an E-Defense shake table, which simulated a 7.5 magnitude quake (check out the video!)"
Lasts? (Score:5, Interesting)
the purpose is to survive not to last. (Score:5, Interesting)
Believe it or not current structural code functions to provide surviveability for it's occupants. I'm an architect in southern california and prior to 1997 buildings were designed to basically allow occupants to escape, however due to the financial toll of northridge the structural code was revamped to prevent flexing which would result in the building not having sever cosmetic damage. This however resulted in drastically increased construction costs. The fact is you want a building that will flex as opposed to break. It always cracks me up because there is a war between wood mfgs and steel mfgs. Currently your typical stick framed building stops at three stories (in southern california) after this you need to switch to steel or concrete. Manufactureres like simpson strong tie are working hard to push the limit of wood to allow them a greater market share.
6-Story Wooden Pagoda Survived 7 Earthquakes (Score:5, Interesting)
Pagoda of Fogong Temple [wikipedia.org]
Yes, it's "wood", but... (Score:5, Interesting)
Disclaimer: IAAAS/IANYAA (I am an architecture student/I am not yet an architect).
Good for them, but it doesn't really surprise me that you can make a building of that type/size earthquake-resistant. While the building is technically "wood", they are using a lot of engineered lumber (lumber that is made from particles/chips of wood held together with a binder). Looking at the pictures in the article, the building is sheathed in OSB (oriented strand board), which acts as a very good shear panel. The floors are supported using TJIs (Truss Joist I-Beams), where the top and bottom of the TJI is made of laminated wood and OSB is used as the webbing of the truss. These things are very strong, and they are anchored on the ends with galvanized steel hangars, which are very secure. The weak point in wood structures is frequently in how the pieces are joined together, and the hangars largely address that. Engineered lumber is increasingly popular in US wood construction, not for earthquake reasons, but because it is very consistent - it comes in the exact size you order, doesn't warp/twist/bow, etc., and it doesn't have knotholes. Where this building uses regular milled lumber they often stack it 6-7 deep to make columns.
They are still using steel - in the foundation and in the tiedown system, to do critical structural work. Nothing wrong with that, it's the smart thing to do. Steel has awesome tensile strength.
My guess is that a mid-rise made using this method would be significantly cheaper than reinforced concrete, and somewhat cheaper than steel. The difference is that a steel framed building will be put together by skilled welders, while the framers putting this building up will tend to be of a lower skill level - one reason this building would be cheaper - and you'll have to keep a closer eye on the construction. Given the need for engineered lumber, selective use of steel, and close attention to how the building is put together, I don't see this as a panacea for earthquake-resistant housing in the third-world. I'm sure they would love it in California, though. The big challenge is ensuring consistent construction and getting the changes in the building code (particularly in CA, which is more earthquake conscious than other states). Beyond that, it's just a question of cost.
Code enforcement (Score:5, Interesting)
There's no technical problem making a wood building that strong. It's the enforcement that's the problem. Wood has good tensile strength, but the joints usually used in wood construction don't.
A few years ago, after some hurricanes, many Florida builders were discovered not to be building to code. Hurricane-proofing for small wood structures mostly consists of putting in metal brackets at joints to give wood-to-wood joints tensile strength. Not only do the brackets have to be put in, nails have to be hammered into all the holes in the brackets. Many contractors were sloppy about that, resulting in a big loss of tensile strength and major damage (like roofs ripped off) during hurricanes.
A big problem in the Third World is bad concrete mixes. Much concrete construction goes up without enough cement in the mix, and that results in building collapses.
Here's a good project for someone - develop a low-cost hand held device for concrete testing. [state.il.us] The existing techniques are slow, labor-intensive, and a pain to use. Tests for hardened concrete usually involve cutting out a plug and sending it to a lab elsewhere. Small portable devices would be a big help here.
Re:Unimpressive... (Score:1, Interesting)
That "crap" is a lab experiment. It's a proof of concept well ahead of anything we've had yet. Also it's "empty and naked" to see what's going on with the structure during the shake. I wish we had the internal footage -- those are always wonderfully dramatic.
Your attitude is akin to saying every mission before Apollo 11 was crap, that "proves precisely nothing". Reel it in an maybe more people will bother to have conversations with you, and you'll become less ignorant.
Yes, all the missing items have effects, though not necessarily what one would expect, and seldom simple. Drywall for instance is very heavy but also makes studwalls into box structures. Plumbing, even loaded, is relatively light. That's more of a rigidity issue -- you have to investigate questions like does the plumbing tear out critical portions of this structure -- does it need specially designed bays, different attachment, or can it be installed as we've been doing?
Minor disclaimer: I used to be a carpenter out here on the West Coast. I find this stuff fascinating and rather overdue. The curious should dig around. There's some great vids of the structures the Japanese have put on earthquake-tables. Sometimes fully furnished condos with internal footage.
Re:uh, wow? (Score:3, Interesting)
Two houses. One reinforced. Shaken at the same time.
http://www.youtube.com/watch?v=kc652Zp5qWk [youtube.com]