A thought on the Provo City Center Temple
I'm not sure if I've mentioned this in any past post, but the recent earthquake and tsunami in Indonesia, with its devastating liquefaction, brought this back to mind.
When the Provo City Center Temple was being built, the ground water was found about 18 feet. The two below ground levels would be bringing the depth of the temple foundation down to 40 feet. What the construction company did (which was part of the plans) was to create what essentially became a big bath tub. First the walls, then the floor.
When I read about this, my immediate reaction was the foundation was like a big boat. I'm not sure if it could actually hold the weight of the temple and adjoining structures in a water environment, but my thought is it would float the temple when a big earthquake shakes and liquefies the ground. Other structures nearby will likely receive damage or sink into the ground as a result of the soil liquefaction. But, the temple will float and receive minimal damage.
Some articles referenced reinforcing the brick walls to strengthen them against a large earthquake, but I didn't read anything about the foundation and liquefaction.
The temple was dedicated in March 2016, so I know I had this thought well before that time.
That was a few years ago. It was until I was doing a little research today that I found an actual reference to the foundation being helpful in an earthquake, in this March 2017 article https://www.structuremag.org/?p=11145
Here's the excerpt from the March 2017 Structure Magazine article:
This is important to consider because while the Provo Temple is build in the foothills, over ground that is not likely to liquefy, that is not the case for the Provo City Center Temple. The ground throughout the main part of the city, and extending out to Utah Lake, is highly likely to liquefy with extensive ground shaking.
When the time comes, and a large earthquake strikes the area, the temple will still be standing.
It really is an interesting thought. If the building had remained as it was, an earthquake in the magnitude 6 range would have caused massive damage. An earthquake striking in the Utah valley area of magnitude 7 or higher would probably have caused the old tabernacle to completely collapse.
However, because the building was restored and rebuilt as a temple it was newly constructed to meet high seismic loads. I'm not sure what the earthquake rating it for the structure. But, because of the bathtub foundation I suspect the temple will be able to withstand an earthquakes much larger than the structure itself could withstand.
I think the reason is because liquefied ground is no longer causing structures to shake as violently as they would if the ground were more solid. Of course, in most cases liquefied soil could cause buildings, cars, people, and anything heavy on the surface to sink. In the latest Indonesian earthquake there were witnesses who saw buildings, cars, and people disappear into the ground as the ground, which had turned to mud, swallowing them up.
But, for the objects that can float, just as the soil is liquefying and the earth is still shaking--and often continuing to shake harder and longer--the floating object is essentially lifted out of the worst. There would still be some movement, but in the liquefied areas it is no longer the actual movement of the ground that causes damage, it is the lack of soil/ground integrity that causes buildings to lose structural integrity when their foundations fail to support the weight of the building. This won't be the case for the Provo City Center Temple.
What I think will happen is when a big earthquake happens the ground will begin to liquefy well before the structural earthquake rating of the temple is reached. On more solid ground the horizontal (or vertical) movement of the earth more easily transfers to a building, and the structure needs to be able to withstand this movement. But in a liquid, the movement of the ground below and around the liquid is not transferred through the liquid in the same way. So, I think being on a boat--like structure would cause the structure to fare better during the worst part of the quake.
Of course, the liquefied soil isn't helpful for other buildings with the continued shaking of the earth and liquid ground causing buildings to sink and collapse.
------
Some other articles
https://www.heraldextra.com/special-section/provocitycentertemple/story/a-construction-marvel-provo-city-center-temple-rises-from-the/article_51f883bb-bcc5-5c57-8207-ccf6e1af920d.html
https://www.nicholsonconstruction.com/geotechnical-work/landmark-projects/provo-city-center-temple
https://www.deseretnews.com/article/865578569/Provo-City-Center-Temple-a-feat-of-engineering-hard-work-and-faith.html
When the Provo City Center Temple was being built, the ground water was found about 18 feet. The two below ground levels would be bringing the depth of the temple foundation down to 40 feet. What the construction company did (which was part of the plans) was to create what essentially became a big bath tub. First the walls, then the floor.
When I read about this, my immediate reaction was the foundation was like a big boat. I'm not sure if it could actually hold the weight of the temple and adjoining structures in a water environment, but my thought is it would float the temple when a big earthquake shakes and liquefies the ground. Other structures nearby will likely receive damage or sink into the ground as a result of the soil liquefaction. But, the temple will float and receive minimal damage.
Some articles referenced reinforcing the brick walls to strengthen them against a large earthquake, but I didn't read anything about the foundation and liquefaction.
The temple was dedicated in March 2016, so I know I had this thought well before that time.
That was a few years ago. It was until I was doing a little research today that I found an actual reference to the foundation being helpful in an earthquake, in this March 2017 article https://www.structuremag.org/?p=11145
Here's the excerpt from the March 2017 Structure Magazine article:
"When the bottom of excavation was reached, a waterproofing membrane was installed and a new 18- to 24-inch thick reinforced concrete mat footing was placed. The new sub-basement level is approximately 14 feet below the design groundwater elevation. The mat footing and foundation walls were designed to resist the upward hydrostatic pressures.It was exciting to read what I had come to my mind.
"The micro-piles served several purposes. First, they temporarily supported the exterior brick walls. Second, they served to support the mat footings for the heavy loads of the new structure. The micro-piles also helped mitigate the potentially liquefiable soils that exist on the site. Lastly, they acted as hold down anchors to resist buoyancy forces created by the water table.
"After the new mat footing had been completed, new reinforced concrete foundation walls were constructed between the mat footing and the bottom of the brick walls. Block-outs were formed in the foundation walls around each of the shoring needle beams."
This is important to consider because while the Provo Temple is build in the foothills, over ground that is not likely to liquefy, that is not the case for the Provo City Center Temple. The ground throughout the main part of the city, and extending out to Utah Lake, is highly likely to liquefy with extensive ground shaking.
When the time comes, and a large earthquake strikes the area, the temple will still be standing.
It really is an interesting thought. If the building had remained as it was, an earthquake in the magnitude 6 range would have caused massive damage. An earthquake striking in the Utah valley area of magnitude 7 or higher would probably have caused the old tabernacle to completely collapse.
However, because the building was restored and rebuilt as a temple it was newly constructed to meet high seismic loads. I'm not sure what the earthquake rating it for the structure. But, because of the bathtub foundation I suspect the temple will be able to withstand an earthquakes much larger than the structure itself could withstand.
I think the reason is because liquefied ground is no longer causing structures to shake as violently as they would if the ground were more solid. Of course, in most cases liquefied soil could cause buildings, cars, people, and anything heavy on the surface to sink. In the latest Indonesian earthquake there were witnesses who saw buildings, cars, and people disappear into the ground as the ground, which had turned to mud, swallowing them up.
But, for the objects that can float, just as the soil is liquefying and the earth is still shaking--and often continuing to shake harder and longer--the floating object is essentially lifted out of the worst. There would still be some movement, but in the liquefied areas it is no longer the actual movement of the ground that causes damage, it is the lack of soil/ground integrity that causes buildings to lose structural integrity when their foundations fail to support the weight of the building. This won't be the case for the Provo City Center Temple.
What I think will happen is when a big earthquake happens the ground will begin to liquefy well before the structural earthquake rating of the temple is reached. On more solid ground the horizontal (or vertical) movement of the earth more easily transfers to a building, and the structure needs to be able to withstand this movement. But in a liquid, the movement of the ground below and around the liquid is not transferred through the liquid in the same way. So, I think being on a boat--like structure would cause the structure to fare better during the worst part of the quake.
Of course, the liquefied soil isn't helpful for other buildings with the continued shaking of the earth and liquid ground causing buildings to sink and collapse.
------
Some other articles
https://www.heraldextra.com/special-section/provocitycentertemple/story/a-construction-marvel-provo-city-center-temple-rises-from-the/article_51f883bb-bcc5-5c57-8207-ccf6e1af920d.html
https://www.nicholsonconstruction.com/geotechnical-work/landmark-projects/provo-city-center-temple
https://www.deseretnews.com/article/865578569/Provo-City-Center-Temple-a-feat-of-engineering-hard-work-and-faith.html
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