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Concrete wall instability model

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Project by TopamaxSurvivor posted 01-25-2020 08:36 PM 930 views 0 times favorited 19 comments Add to Favorites Watch

This 1/3” to the foot model is to demonstrate to the Auburn City Mayor and Council that concrete walls need footings and embedded foundations for stability and structural support. That is especially critical in earthquake country where the magnitude 9+ Cascadia Subduction Zone quake is overdue.

The model is made of a few scraps of hardwood I had laying around. The board representing the ground is a piece of pine. Cutting the small pieces on the table saw safely is an art in itself, but I still have all my fingers thanks to my imagination. [:-) Notice my smiley face is wearing his hard hat for safety.

The pieces are 2 inches tall and scaled to the domino. The red one represents a 3 foot section of a 6 foot high concrete wall 8 inches thick. The tallest green piece with the large bottom represents a proper wall with a footing slightly less than 3 feet deep with a 4 foot wide footing 12 inches thick. It is painted green “good to go” as a proper structure. The foundation and footing are gold color. They are gold because they are worth their weight in gold to keep the 32 ton wall standing upright in the wind, through freeze/ thaw cycles and earthquakes.

An engineer’s evaluation said the wall does not meet wind load standards standing on top the ground. Our freeze/ thaw cycles have disappeared into ancient history. The 320th anniversary of the 9+ Cascadia Subduction Zone earthquake is tomorrow, January 26, 2020. Core samples studied at Oregon State show there has never been more than 320 years between events in the last 10,000 years.

The domino is a standard domino size, 2” long, 1” wide and 3/8” thick. The red for “no go” wall section is the same size but only ¼” thick. That is because the wall scaled to the domino demonstrates the wall needs to increase its thickness 50% to have the same base to height ratio as the domino. That base ratio increase should substantially increase the stability of the concrete wall.

The green “good to go” triangular piece is from a book I saw in a museum in the Northeastern U.S. The soil in that area is quite rocky. Farmers removed the rock from the fields to build stone walls. The book was How to Build Stone Walls published about 1713. It said to build a wall with the embedded foundation half the height of the wall. To build a stable wall on top of the ground, the base needs to be 2/3 of the height. That piece represents a 3 foot section sized properly to be built on top the ground. Quite a dramatic departure from the red “no go” model the city allows to be used.

The green piece with the small gold stripe on the bottom is to insert into the mortise in the board. This demonstrates the green “good to go wall” embedded into the “ground.” Again, the gold embedded foundation is worth its weight in gold to keep the 32 ton wall standing upright. I cheated making that narrow mortise. A couple zips with the table saw rather than trying to find a small 1/8” chisel made it quick and easy. I glued a couple small scraps in to fill the ends of the saw cuts. Hopefully, it will demonstrate to the mayor and council how much more stable the embedded wall will be than the red wall section and the domino standing on top when the wind blows or the ground shakes. The red wall section being less stable than the domino will hopefully make this project a success.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence





19 comments so far

View Phil32's profile

Phil32

932 posts in 540 days


#1 posted 01-25-2020 09:21 PM

“Core samples studied at Oregon State show there has never been more than 320 years between events in the last 10,000 years.”
If that refers to 9+ quake events, it could be because the stresses are being relieved by smaller quakes.

Interesting nevertheless.

-- Phil Allin - There are mountain climbers and people who talk about climbing mountains. The climbers have "selfies" at the summit!

View MaxinCT's profile

MaxinCT

59 posts in 2227 days


#2 posted 01-25-2020 10:16 PM

”NEVER” been more than 320 years between events….That’s the amazing thing about ole Mother Nature….she doesn’t pay attention to records, models or forecasts…just ask any weather forecaster in New England:)

View Lenny's profile

Lenny

1650 posts in 4164 days


#3 posted 01-26-2020 12:24 AM

Lots of thought went into this. Well done Bob.

-- On the eighth day God was back in His woodworking shop! Lenny, East Providence, RI

View swirt's profile

swirt

4746 posts in 3609 days


#4 posted 01-26-2020 02:16 AM

Good work trying to teach with a model. I hope your effort pays off.

-- Galootish log blog, http://www.timberframe-tools.com

View Dark_Lightning's profile

Dark_Lightning

3807 posts in 3746 days


#5 posted 01-26-2020 03:51 AM

The walls won’t fall down, so there will be lots of inadvertent swimming pools when the water comes! :D

-- Steven.......Random Orbital Nailer

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#6 posted 01-26-2020 10:01 AM



“Core samples studied at Oregon State show there has never been more than 320 years between events in the last 10,000 years.”
If that refers to 9+ quake events, it could be because the stresses are being relieved by smaller quakes.

Interesting nevertheless.

- Phil32

Smaller quakes do not relieve tectonic plate collisions. The Jaun de Fuca plate is lifting the continental shelf. Eventually it breaks off. The continental shelf will drop up to 3 meters +/-. We have ghost forests, dead trees aged with tree ring data, that were growing the summer before an event. They die the following summer because they are standing in salt water because the land dropped slightly below sea level.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#7 posted 01-26-2020 10:03 AM


”NEVER” been more than 320 years between events….That s the amazing thing about ole Mother Nature….she doesn t pay attention to records, models or forecasts…just ask any weather forecaster in New England:)

- MaxinCT


No, she doesn’t. But the cycle determines the probability. If it had happened 50 years ago, I would not have built the model to demonstrate their ignorance to the council.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#8 posted 01-26-2020 10:05 AM



Lots of thought went into this. Well done Bob.

- Lenny


Thanks Lenny. Too bad I have to deal with ignorance of that extreme level. Most kids figure out these principles playing with blocks before they start school ;-))

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#9 posted 01-26-2020 10:08 AM



Good work trying to teach with a model. I hope your effort pays off.

- swirt


Thanks. If the earthquake doesn’t tip it or throw it (peak ground accelerations can be 1.25 times the force of gravity and move vehicles 100 yards in 5 seconds; 50 mph) making a planting bed for roses along it could be a fatal mistake!

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#10 posted 01-26-2020 10:10 AM



The walls won t fall down, so there will be lots of inadvertent swimming pools when the water comes! :D

- Dark_Lightning


I will have to get about 400 feet deep before there will be enough water to swim along the wall. ;-))

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View torus's profile

torus

396 posts in 1050 days


#11 posted 01-26-2020 03:00 PM



...
Thanks Lenny. Too bad I have to deal with ignorance of that extreme level. Most kids figure out these principles playing with blocks before they start school ;-))

- TopamaxSurvivor

This was my first thought. Mayor and Council had needs for kindergarten level of demonstration…. [[:( (double hard hat)

-- "It's getting better..." - put this on my RIP stone!

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#12 posted 01-26-2020 06:33 PM


...
Thanks Lenny. Too bad I have to deal with ignorance of that extreme level. Most kids figure out these principles playing with blocks before they start school ;-))

- TopamaxSurvivor

This was my first thought. Mayor and Council had needs for kindergarten level of demonstration…. [[:( (double hard hat)

- torus


If this project does not succeed, it is probably worse than double hard hat time. Most likely a body bag shortage or mass grave [[[-((

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View mafe's profile

mafe

12353 posts in 3726 days


#13 posted 02-10-2020 10:18 AM

Super nice idea, to make little models.
Fine work.
Best thoughts,
Mads

-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

View TopamaxSurvivor's profile

TopamaxSurvivor

18818 posts in 4313 days


#14 posted 02-10-2020 06:35 PM

Thank you Mads. I hope they see the light ;-))

The problem is if an explanation is required for something this basic, no explanation will be sufficient ;-((

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

View mafe's profile

mafe

12353 posts in 3726 days


#15 posted 02-10-2020 10:30 PM

As an architect I an aware of the power of a model.
Yes fingers crossed.

-- MAD F, the fanatical rhykenologist and vintage architect. Democraticwoodworking.

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