Hoover Dam

[walkinghorse]

It seems that the weight of a dam and the weight of the water in the reservoir behind it has the possibility of causing earthquakes in areas of no KNOWN faults.
One source of this. Earthquakes Triggered by Dams | International Rivers
Hence my original post regarding changing water levels, though it was intended to be humorous especially the source Ripley's Believe It or not. Sort of like some of my college exam grades while attempting study of civil engineering. According to the professors I needed to take off my shoes when getting into higher math!
Thanks to Big Cholla, rwsmith, and others for providing serious information about dam structures !

 

[Gamecock]

The Hoover Dam design is called a "Gravity Arch". The water against the face pushes the abutments of the arch into the rock walls of the canyon with a force directly proportional to the height of the water. The weight of the concrete is sufficient to prevent the water pressure from pushing under and lifting it out of position.

But the problem is LACK of water. Lake Mead is down over 100', and not recovering.

 

[SPEEDGUNNER]

Now THIS is a discussion you don't expect to find on a gun forum, but wow was this an enjoyable thread! Having visited Hoover Dam and Coulee Dam in Washington state in my travels, I have always marveled at their construction, and the fact they were built in a simpler time.

 

[DWalt]

"I still have my first serious Surveyor's Transit. It is a German made Lietz. It is totally mechanical and optical. I'm sure that today's graduate civil engineer wouldn't know how to use it and get any good results."


I kept my David White transit/level for many years, and never used it. Ended up selling it on Craigslist a few years ago for $50 to a guy who wanted to use it for laying out fences around his property. No one uses transits anymore. Sort of like slide rules and sextants. Although I still have a 6" K&E slide rule in my car glove box to figure gas mileage.

 

[Big Cholla]

Slide Rule, What's That?

"I still have my first serious Surveyor's Transit. It is a German made Lietz. It is totally mechanical and optical. I'm sure that today's graduate civil engineer wouldn't know how to use it and get any good results."


I kept my David White transit/level for many years, and never used it. Ended up selling it on Craigslist a few years ago for $50 to a guy who wanted to use it for laying out fences around his property. No one uses transits anymore. Sort of like slide rules and sextants. Although I still have a 6" K&E slide rule in my car glove box to figure gas mileage.

LOL! I carry a 6" K&E in the breast pocket of my leather motorcycle jacket for the same purpose. Does that make us Luddites? And, while sitting on my Harley at a gas station and doing that simple calculation with the slide rule, I have gotten some really strange looks. I don't carry one in a vehicle because both my wife's auto and my pickup have built in MPG calculators. ..........

 

[Big Cholla]

You and 'They' are Right!

It seems that the weight of a dam and the weight of the water in the reservoir behind it has the possibility of causing earthquakes in areas of no KNOWN faults.
One source of this. Earthquakes Triggered by Dams | International Rivers
Hence my original post regarding changing water levels, though it was intended to be humorous especially the source Ripley's Believe It or not. Sort of like some of my college exam grades while attempting study of civil engineering. According to the professors I needed to take off my shoes when getting into higher math!
Thanks to Big Cholla, rwsmith, and others for providing serious information about dam structures !

We lived in Boulder City during the filling of Lake Mead the first time. BC was known for multiple small earthquakes as the result of the weight of the water in the lake forcing the crust of the earth downward slightly. In the late '50s there was one earthquake that was pretty sharp. I was awake lying in bed with my window open and first heard all the neighborhood dog starting to howl. Then I could hear buildings and other things rattling. Then our house got a really good shake. Years later while working at the Nevada Test Site, I heard the same sound (except for the dogs) and felt the same motion sensation when we set off an atomic bomb underground.

BTW; When the lake went down significantly the first time, we also had very small earthquakes in BC as the earth's crust rose back some. None of those quakes bothered Hoover Dam in the slightest. ...

 

[walkinghorse]

You and 'They' Are Right!

Now you know my specialty, If you can't dazzle them with brilliance, baffle them with baloney! You know what I mean! Don't want to slander balogna.

My life after working for a GC for many years, surveying and layout, was working as a construction administrator (clerk of the works for us of a earlier time) for architects and/or engineers, though the projects were hospitals, and high rises, and one bridge. Therefore being in the middle, one develops 'baloney' skills! Made my professors happy, staying away from design!

 

[mr.jbk79]

Besides the dam, I also was fascinated with the O'Callaghan
-Tillman memorial bridge. The largest single-arch bridge in North America. Sorry about the partially obstructed pic, my other shot keeps rotating sideways. Almost 900 feet above the river.

 

[steelslaver]

Wasn't one of the pours for that bridge supposed to big the biggest monolithic pour at the time it was made? I watched a program about it on TV and the coordination of delivering and pouring the in spec concrete was extremely critical for one of the anchors on one side.

Search show several out huge single pours have been made in recent history.

 

[Big Cholla]

Rule of Thumb Design

Now you know my specialty, If you can't dazzle them with brilliance, baffle them with baloney! You know what I mean! Don't want to slander balogna.

My life after working for a GC for many years, surveying and layout, was working as a construction administrator (clerk of the works for us of a earlier time) for architects and/or engineers, though the projects were hospitals, and high rises, and one bridge. Therefore being in the middle, one develops 'baloney' skills! Made my professors happy, staying away from design!

You made me bring back a memory. After starting to work as a Construction Engineer and having had 8 years behind me both as a working Carpenter and then a Millwright, I knew most of the 'slip-stick designs' of structures wound up with a safety factor of from 200% to 300% because of what was called "The Engineering Fudge Factor". Then as computer programs were perfected to calculate building design structure strength of materials down to 6 or 8 decimal places, I watched the actual safety factor in structure reduced down to about 100 %. That means the structure is twice as strong as what the Structural Engineering design called for. I marveled at the unintended consequence of advanced computer programming and its resulting reduction in structure design safety factors. I'm still not sure that I am comfortable with that reduction. Today when I'm up high in a high rise building that was built in the last 10 years I am sort of tense waiting for the big earthquake that might be coming.

 

[steelslaver]

I am not an engineer, but I have always found it a solid idea to practice the The Engineering Fudge Factor.

 

[Rustyt1953]

The engineering behind the dam has always fascinated me. In researching more info online, I stumbled across this:

Concrete that could stop an EMP.

Scientists Invent Concrete That Could Stop an EMP

 

[6518John]

You made me bring back a memory. After starting to work as a Construction Engineer and having had 8 years behind me both as a working Carpenter and then a Millwright, I knew most of the 'slip-stick designs' of structures wound up with a safety factor of from 200% to 300% because of what was called "The Engineering Fudge Factor". Then as computer programs were perfected to calculate building design structure strength of materials down to 6 or 8 decimal places, I watched the actual safety factor in structure reduced down to about 100 %. That means the structure is twice as strong as what the Structural Engineering design called for. I marveled at the unintended consequence of advanced computer programming and its resulting reduction in structure design safety factors. I'm still not sure that I am comfortable with that reduction. Today when I'm up high in a high rise building that was built in the last 10 years I am sort of tense waiting for the big earthquake that might be coming.

Or just a 35 MPH wind. I think someone ate the fudge out of the fudge factor here.

[ame]https://m.youtube.com/watch?v=XggxeuFDaDU[/ame]

 

[rwsmith]

You mean...

But the problem is LACK of water. Lake Mead is down over 100', and not recovering.

Rather than bursting from too much pressure the dam will tip over into the lake bed?????

 

[rwsmith]

it could have been....

Or just a 35 MPH wind. I think someone ate the fudge out of the fudge factor here.

Tacoma Bridge Collapse - YouTube

That one could have been 10 times as strong and it wouldn't have helped. It was the shape that caused extreme resonance that brought it down. I'm really surprised that it didn't collapse much sooner under all that flexing. They have retrofitted baffles and extra weight in certain places on existing bridges which, thanks to computers can be analyzed in air flow.

PS You guys are a tad older than me, I took the last class offered at my school in slide rule and I never had to use one on the job. I can't say that any learning is useless, but that comes pretty close. Like being trained to drive a wagon and your first job is driving a car.

PPS I've made a long hobby of studying engineering failures and in the case of one building, the trusses were plenty strong in weight carrying capacity, but they neglected to allow for the twisting that a truss does when it is loaded. In spite of being able to carry tons, all the joining gusset plates had to do was bend like a piece of paper. Hardly any resistance at all to twisting motion. Needed heavier gusset plates, but most importantly, lateral bracing.

Another favorite is when a foreman noticed a crack in the floor of a building he was erecting. He stopped at a hardware store to get some DAP, Red Devil or something to fix the crack. When he got back from lunch, the building was flat on the ground.

One building had the system for hauling concrete up as it was to be poured down pat. Except that the concrete laying equipment failed. But concrete kept being lifted to the top floor. Didn't take long for the extra weight to bring the whole thing down.

PPPS I wonder if the guy with the concrete patch got a refund?

 

[walkinghorse]

You made me bring back a memory. After starting to work as a Construction Engineer and having had 8 years behind me both as a working Carpenter and then a Millwright, I knew most of the 'slip-stick designs' of structures wound up with a safety factor of from 200% to 300% because of what was called "The Engineering Fudge Factor". Then as computer programs were perfected to calculate building design structure strength of materials down to 6 or 8 decimal places, I watched the actual safety factor in structure reduced down to about 100 %. That means the structure is twice as strong as what the Structural Engineering design called for. I marveled at the unintended consequence of advanced computer programming and its resulting reduction in structure design safety factors. I'm still not sure that I am comfortable with that reduction. Today when I'm up high in a high rise building that was built in the last 10 years I am sort of tense waiting for the big earthquake that might be coming.

Teflon or other slip type connections at a buildings base connection with the foundations have always made me nervous. Watching wind tunnel testing of building sway limits to mininimize nausea in building occupants, and concept of floor to ceiling windows without any cross pieces for visual reference by occupants is interesting also!
Reducing the safety factors means less mass, e.g. less cost, and enhances building sway, but the square foot cost comes down for the developer. Modern construction in high rises takes sea sickness to new heights, pun intended.
Aerodynamics for buildings both alone and as a part of surrounding buildings a phase of building engineering that is a new frontier! Tip vortices at building edges are sometimes trial and error.

 

[rwsmith]

Most of us.....

Now THIS is a discussion you don't expect to find on a gun forum, but wow was this an enjoyable thread! Having visited Hoover Dam and Coulee Dam in Washington state in my travels, I have always marveled at their construction, and the fact they were built in a simpler time.

I wish I could say I collected and shot guns all my life for a living, but a LOT of us have had some experience outside the gun world in order to support collecting and shooting guns.

Being as interesting as many people are here, I'd bet their backgrounds are just as interesting. Like, I never worked on an atomic bomb project.

Now an outfit I worked for had a non-destructive testing (strong radioactive stuff) lab in a van. One of the older guys got dissatisfied and took the van and went on a cross country trip with his family and even charged a set of tires to the company. It took a couple of weeks to find him. It was potentially dangerous, but turned out to just be funny.

 

[walkinghorse]

One Task That Slide Rules Beat Computers!

"...PS You guys are a tad older than me, I took the last class offered at my school in slide rule and I never had to use one on the job. ..."

Killings flies or mosquitos in the job trailer!

 

[Big Cholla]

Wrong Fly Swatter!

"...PS You guys are a tad older than me, I took the last class offered at my school in slide rule and I never had to use one on the job. ..."

Killings flies or mosquitos in the job trailer!

You can use your slide rule if you want, but I always used the leather sheath my 12" K&E slide rule was carried in. ......

 

[PatriotX]

Excellent thread, very informative -thanks !


I took a trip into the guts of the dam as a kid, and will always remember the walls weeping water.