Grand Canyon Skywalk - Pretty Cool...Eh! 1

[JStephen]

A couple of interesting things. They do mention the 71,000,000 lbs in the video. Also, I notice that architects sketch shows beams about 24" deep- compared to 72" for the finished design- a minor change! Lastly- the guy in the video mentions the limestone there is adequate for 16,000+ PSI- is that reasonable, or is he confusing PSI with PSF (he interprets it that the limestone is 4x stronger than concrete).

 

[JStephen]

On Wikipedia, I found a quote (no source given) that states:
"The Skywalk will be able to hold 70 tons of weight, allowing for 800 people weighing 175 lbs. each to stand on the bridge. "

Elsewhere on one of the official sites, I find a statement thus: "On May 2005, the final test was conducted and the stucture passed engineering requirements by 400 percent, enabling it to withstand the weight of 71 fully loaded Boeing 747 airplanes (more that 71 million pounds). The bridge will be able to sustain winds in excess of 100 miles per hour from 8 different directions, as well as an 8.0 magnitude earthquake within 50 miles. More than one million pounds of steel will go into the construction of the Grand Canyon Skywalk."

This sounds like the 71,000,000 lbs is perhaps the ultimate strength of the foundation support points or something of the sort- but very different from any load proposed on the structure itself. This "load test" was prior to any actual steel construction being done, evidently.

 

[COEngineeer]

16000 is correct i bet. The 4000 psi concrete we use does go up pretty high after a few months.

 

[unclesyd]

Here it mentions the worlds largest bolt???.

http://www.grandcanyonskywalk.com/contact.html

Here DSI doesn't show anything like "The Dywidag" mentioned in the picture caption shown in the above. Might be holding off until the Sky Walk proves out.
It would be interesting to know how many the bolts are used and how long they are.

http://www.dsigroundsupport.com/products/Threadbar_Properties.html

 

[JStephen]

I suspect they mean the "world's largest Dywidag bolt".

Some material here on the dampers:

http://www.motioneering.ca/User/Doc/2006q2_at_the_moment.pdf

http://archshrk.com/

From this paperL

http://www.baldersoninsurance.com/September_2006.doc

"Scheduled to open in October 2006, the skywalk designed by Lochsa Engineering in Las Vegas is cantilevered atop the cliff with 94 steel rods that bore 46 feet into the limestone rock. It can support l70 tons of weight, equivalent to 700 big men, but its maximum occupancy is set at 120 people. Three oscillating steel plates weighing 3,200 pounds that are inside the hollow bridge beams act as shock absorbers. They move up and down to neutralize the vibrations from foot traffic and vertical wind gusts that may be up to 94 miles per hour. The sides are made from strengthened, three-inch thick, five-foot-tall glass walls."

Somewhere, I saw 2.5" bolts mentioned. With 94 bolts 2.5" diameter, 71,000,000 lbs gives a stress of 154,000 psi, which seems inordinately high.

 

[unclesyd]

I think they should hold a worldwide lottery to see who will be the first base jumper to sail off into the sunset.

 

[dimjim]

In the video, they mention 108 drilled holes
and I assume that means 54 per side and that
is how many bolts are going to be used.
I cannot comprehend why they would not use some
angular support from the bottom.
I agree that this is an amazing project!

http://www.grandcanyonskywalk.com/video/video.html

 

[swearingen]

I'll volunteer to be the second person to walk out there - let the first person go to make sure it holds up statically and let everybody else after me make sure its fatigue properties are OK...

I saw this a few months ago and threw out the 71 million pound load as garbage. I agree with previous posters about that number migrating over from the foundation side of things. What may have happened is that the square area of the compressive portion of the foundation, coupled with the compressive strength of the rock was leaked. I figure 71 million pounds at 16,000 psi gives a little over 15 square feet per side of compressive area for those beams, which is reasonable.

 

[dimjim]

FOETS,
How did you capture the picture and post it
to the web? That is impressive.

 

[FOETS]

Dimjim

see faq238-1161

you need to put your pictures and emoticons into a hosting server such as

http://www.tinypic.com

then copy and paste the provided link into the eng tips message

FOETS
"social drinker with a golfing problem"

 

[JStephen]

An update on the project here. Still sounds optimistic- like they'll be marching people out there just as soon as they get it slid out into place.

http://www.grandcanyonskywalk.com/update.html

 

[HgTX]

Are they going to make people put on booties when they walk out there, or is it quickly going to get as scuffed as the glass floor in the CN tower? ($25 oughta include a pair of paper booties.)

Hg


Eng-Tips policies: faq731-376

 

[JStephen]

I saw somewhere on that site where they mentioned booties, so I think that is a part of the plan.

I'd tend to go with the leaning walls as in the Gateway Arch rather than a glass floor, but it's a done deal.

 

[COEngineeer]

Why not put a film that can be replaced a lot cheaper every a few months?

 

[FOETS]

Nice to see they are going to send out the media and a few politicians first.

 

[COEngineeer]

I think they should hang a 747 on the tip of the bridge lol.

 

[unclesyd]

This thing is now opened. For $25.00 you can walk out on it and scare yourself to death.

 

[michfan]

I can't even watch while Indy jumps across that invisible bridge in the Holy Grail movie...you aren't going to see me out on that any time soon.

 

[COEngineeer]

If it is open, how come I couldnt fint any pictures when I googled it?

http://www.krmconsultants.com

 

[TXStructural]

The official website says that it opens on Mar 27. See FP for the website.