🧵 Why was the Baltimore bridge pillar hallow?
Anonymous at Wed, 27 Mar 2024 16:32:11 UTC No. 16099488
Is that normal construction for large concrete bridge pillars?
Would the pillar have held if it was built of solid concrete?
Anonymous at Wed, 27 Mar 2024 16:36:37 UTC No. 16099492
To minimize the weight, if it was solid that pilar would weight more than the whole bridge under maximum loading.
It's common for concrete structures to be hollow to reduce the weight.
t. former concreter
Anonymous at Wed, 27 Mar 2024 16:38:28 UTC No. 16099495
>>16099492
Would the pillar have held if it was solid concrete?
Why is weight of the pillar a factor in construction?
Anonymous at Wed, 27 Mar 2024 16:42:34 UTC No. 16099498
>>16099495
>Would the pillar have held if it was solid concrete?
Yes but you would need to drastically improve the foundation so it doesn't sink under all that extra weight.
>Why is weight of the pillar a factor in construction?
The foundation is the ultimate limiting factor for the weight of any construction. If you don't have access to stable bedrock it can be a major problem with buildings as big as hospitals moving and cracking.
Anonymous at Wed, 27 Mar 2024 16:54:40 UTC No. 16099513
>>16099498
>drastically improve the foundation so it doesn't sink under all that extra weight.
Is it possible to estimate how much it would have cost to improve the foundation to keep the pillar from sinking?
This bridge collapse is going to cost probably a whole lot more right?
Anonymous at Wed, 27 Mar 2024 17:00:00 UTC No. 16099525
>>16099513
Wait for the report, I don't know anything about what the foundation or bedrock in that area.
They might have been forced to use a "floating foundation" which has nothing to do with water but the fact soil / sand acts like a liquid if you put enough weight on it.
Those are a bitch and I worked on a 5 story college buidling with a floating foundation that was moving.
On land it was cheaper to fix it than knock it down and start again but in a river the math is likely different.
Anonymous at Wed, 27 Mar 2024 17:46:54 UTC No. 16099593
>>16099525
It is actually pretty shallow and more part of the Bay than a river. Does this bathymetry map provide enough information to make an educated guess at the extra cost of making the pillar solid concrete?
Anonymous at Wed, 27 Mar 2024 17:48:15 UTC No. 16099595
>>16099593
forgot pic
Anonymous at Wed, 27 Mar 2024 20:23:48 UTC No. 16099859
>>16099593
>>16099513
>This bridge collapse is going to cost probably a whole lot more right?
That's the wrong question. The right question is "Would designing all bridges to use solid core pylons more expensive than a bridge collapse due to impact every x years nationwide?"
The answer to the first is "probably not." The cost is probably several times the current cost of the bridge. The cost of the collapse is the cost of the bridge, plus the cost of the seven people who died, plus the cost of blocking the bay.
The answer to the second question is "obviously not." I think bridge collapses due to ship strikes are like once per 50 years or something? It's absurd to upgrade every bridge ever for something that barely ever happens.
Anonymous at Wed, 27 Mar 2024 20:40:09 UTC No. 16099905
>>16099859
https://www.nbcwashington.com/news/
>In the period from 1960 to 2015, there have been 35 major bridge collapses worldwide due to ship or
barge collision with a total loss of life of 342 people. T
https://conference-service.com/pian
Anonymous at Wed, 27 Mar 2024 20:47:23 UTC No. 16099927
>>16099495
>Why is weight of the pillar a factor in construction?
You can make it as heavy as you want, but if you build it hollow while keeping the weight constant it will be stronger, i.e two pillars of the same mass, one hollow and one solid, the hollow one would be stronger.
Because strength increases with the cross section.
Anonymous at Wed, 27 Mar 2024 21:17:15 UTC No. 16099996
>>16099498
You don't need foundation when you have Arches.
Anonymous at Wed, 27 Mar 2024 21:38:50 UTC No. 16100033
>>16099996
why don't modern bridges use arches like this?
Anonymous at Wed, 27 Mar 2024 22:40:00 UTC No. 16100121
>>16100033
Because they aren't built solely under compression