PopSci's "innovation of the year"

[Dr Mordrid]

Sometimes it's the little things that matter;

The HurriQuake nail

http://www.popsci.com/popsci/flat/bown/2006/product_75.html

Hurricane winds rip apart nailed-together walls, and earthquakes shake houses so violently that a nailhead can pull straight through a piece of plywood. Since we can’t stop natural disasters, Bostitch engineer Ed Sutt has dedicated his career to designing a better nail. The result is the HurriQuake, and it has the perfect combination of features to withstand nature’s darker moods. The bottom section is circled with angled barbs that resist pulling out in wind gusts up to 170 mph. This “ring shank” stops halfway up to leave the middle of the nail, which endures the most punishment during an earthquake, at its maximum thickness and strength. The blade-like facets of the nail’s twisted top—the spiral shank—keep planks from wobbling, which weakens a joint. And the HurriQuake’s head is 25 percent larger than average to better resist counter-sinking and pulling through. The best part: It costs only about $15 more to build a house using HurriQuakes. $45 per 4,000

Article on the creator and the full story;

http://www.popsci.com/popsci/flat/bown/2006/innovator_5.html

Sutt’s bosses at Bostitch must be happy too. The company is selling every HurriQuake nail it produces and has been doubling production capacity every month. Although the nail is currently available only in the Gulf region (it adds about $15 to the cost of an average 2,000-square-foot house), the company is adding new production lines to meet nationwide demand. Meanwhile, the nail is getting rave reviews from building-technology experts.

[Tjalfe]

kinda looks like this invention, does it not?

[Jessterw]

Except that traditional screws don't fare any better in hurricane force winds either, nevermind that most home construction work utilizes nails and not screws.

[Brian Ellis]

How about bricks and mortar in a reinforced concrete skeleton? This is mandatory here for most buildings, including homes, exactly because of earthquakes. The design requirements are no collapse up to Richter 9, although structural damage will happen at >7.5. To date, the worst my house has suffered is 5.1 with absolutely no damage, not even cracked plaster. It is built on the anchored raft-roof pendulum principle.

Fortunately, we have no hurricanes and tornadoes are rare. In the 8 years I've lived here, I've read perhaps 2 or 3 reports where extreme wind has lifted a roof or three with a small handful of injuries and I think even a death or two. Two people died a month ago when their car was swept to sea in a flash flood.. On the whole, a fairly safe place to live, despite the earthquakes.

[TnT]

Cool!

People who say that there are no more inventions and innovations don't realize there are an infinite number of problems to solve.

[MultimediaMan]

Houses built with the right screws would be stronger, but would end up being quite a bit more expensive because Screws are more expensive than Nails and also the issue of "Screw jacking".

The measures necessary to prevent "Screw jacking" (two parts being fastened together with a wood screw separating during assembly because the screw does not "start" correctly and actually pushes the two parts apart at the fastener joint - jacking can also occur after initial assembly due to wood seasoning.) Solutions to this include using a shanked screw, which only has threads at the tip portion of the screw. The only problem with this is that the framer would have to have several different shank lengths of screws just to allow for jacking (for 2x4s, 4x4s, paneling, etc...), either that or risk using a screw which might have too much or too little shank length and be prone to jacking or stripping. Another solution is to counter-bore the screw hole on the part being fastened through, which requires drilling the hole, then running the screw into it, the risks being not setting the counter-bore depth correctly resulting in jacking on a too-short-bored hole, or stripping on a too-long-bored hole.

Then of course comes the issue of stripped holes: with power drivers having more speed and torque than ever, the end user has to be mindful of just how easy it is to go too far: it is extremely easy to to strip a hole using a modern driver (I deliberately use an older Black and Decker 9.6v driver on wood rather than the larger DeWalt 18v or AC powered drivers-which are used primarily for drilling and counter-boring. If I'm driving a lag bolt, I'll use one or the other around the house.)

There are quite a few Post-Katrina studies which actually encourage the use of Screws in a conventional wood-framed house, but assembly issues such as jacking and stripped screw holes have resulted in building codes and inspection methods which are unattractive to contractors - Nails are here to stay unless you are willing to pay big time - mostly in man-power (which is about 50% of the total cost cost per square foot of the house being built) - for a screw-fastened house.

There are a couple of other neat innovations for the building trades regarding storm or quake damage which are fairly recent: the modern Hurricane Clip (Article), which is nothing more than a metal bracket(s) which fasten a Truss segment of the roof to the top plate of an exterior wall. Most buildings which lose their roofs had ones which merely relied on gravity and nails to do the job.

It is quite possible to retrofit existing homes with these things.

[Dr Mordrid]

How about bricks and mortar in a reinforced concrete skeleton? This is mandatory here for most buildings, including homes, exactly because of earthquakes. The design requirements are no collapse up to Richter 9, although structural damage will happen at >7.5.

A better strategy is a flexible building that can absorb motions without the structure failing, which is how skyscrapers are built. That tech is now filtering down.

The biggest cause of injury these days in earthquakes is falling bricks, glass etc. combined with the outside surface of the concrete failing, which a brick & mortar design doesn't help with. In hurricanes its failure of the siding, roof and roof/wall junction; something these nails and the clips MMM mentioned help with immeasurably. Here's a picture of one designed to hold a roof truss to the wall;



They cost all of a few dollars each and massively strengthen the structure. Cheap insurance IMO.

kinda looks like this invention, does it not?

Ring shank nails are more durable in a moving structure than screws. In my experience screws act like saw blades in such a situation, hollowing out the screw hole as the inclined plane if the screw rotates even slightly (stripping). Ring shank nails don't act this way when they're rotated because the rings are not at an incline; they're parallel to the plane of rotation. As such the wood between the rings generally stays intact and retains the nail. Add increased humidity from an incoming storm and the wood swells & tightens around the nail, making the joint even stronger.

Some ring shanks even come with a glue on their surface that melts into the wood when driven to reinforce its surroundings.

[Brian Ellis]

A better strategy is a flexible building that can absorb motions without the structure failing, which is how skyscrapers are built. That tech is now filtering down.

I agree that this is the rule for skyscrapers, but is not really suitable for one- and two- storey villas, which are the rule here. There isn't enough flexion possible in a 3 - 6 m high structure (unless you have rubber girders! ). The policy then, for villas, is to have a super-rigid structure which has a heavy inertial weight in the roof but can move at ground level. In my house, the concrete roof beam has a section of 60 x 40 cm with 36 2 cm reinforcements in a cage structure. This is triangulated to 9 columns with attachments at 3 points - and it is just less than 10 m long. I'm in a class 2 earthquake zone (historically <6 Richter). Those in class 1 (>6 Richter) are even stronger and apartment/office blocks are limited to 5 storeys. Nicosia is in class 3 and has the highest "skyscrapers" (I think the highest is ~10 storeys, but am not sure; I don't know whether there is a restriction on height for this or any other reason).

IIRC, we have had only 3 serious but not major quakes in recent years, in 1995 (5.8, 2 deaths from falling masonry, ~150 injuries), 1996 (6.4, no deaths, ~50 injuries, mostly minor) and 1999 (5.1, no deaths, 2 injured by panic, jumping off balconies and breaking their legs!). In these 3 events, no buildings constructed using the current norms were seriously damaged. This compares with many recorded deaths and major damage in older events with poorer constructed buildings. However, we are always apprehensive of a big-un like those that destroyed whole cities in the past, although seismologists do not predict one within the next 50 years, at least. At the moment, the Cyprian arc fault is fairly relaxed. The Mesaoria fault seems to have stopped (it destroyed the ancient city of Salamis/Engomi in the 4th c. BCE and again in the 2nd c.; in the 1950s, I snorkelled over the ancient port of Salamis and could see the amphorae still lined up on the quays (and now cemented in by natural processes). The 2nd c one dropped the quays 4 - 5 m! The attached photo, which I took in July, shows the Roman Gymnasium in Salamis destroyed in the same event (the columns were re-erected ~100 years ago).