Not exactly a breaking news per-se for us laymans/public, but the following could be an interesting scoop if you are involved in the construction profession/sector.
Here's a short analysis Tweet on the Kerch Strait Bridge that suffered a massive explosion, of which several sections of the bridge collapsed yesterday as a result. I'm neither a civil/structure engineer nor an architect, therefore anyone who has better knowledge and technicalities on this subject can add more information or rectify anything if found inaccurate.
Source:
Unroll:
What do you guys think of this?
I am qualified to answer this. Papers and all.
I wrote three posts from the Ukraine war thread about the incident but they mostly focus on general issues:
Okay I take back what I said about infrastructure not being hit, looks like they are and reports are coming in now. Network connectivity dropping across multiple oblast:
www.sinodefenceforum.com
And some said Russia had no way to escalate anymore without resorting to nuclear weapons
www.sinodefenceforum.com
Seems like an old video of mercenaries getting caught in a firefight, no location is given and they seemed to be behind decent cover.
www.sinodefenceforum.com
Now regarding the assessment.
I wouldn't take anything anyone says on Twitter seriously especially if it is a simple opinion on a complex subject. Twitter works on principles which employ narcissism, polarization and conflict so anything that you read there is going to be influenced by those three, often in conjunction. And then you are not only not informed but maliciously misinformed.
So what's the truth? China doesn't have a "better" way of designing bridges. It is a way of designing bridges that is better
for China.
For example reinforced concrete is very energy intensive product that only makes economic sense if you have all the necessary infrastructure already in place. This for example is why in the US despite masonry and concrete being a superior building material majority of low-rise housing construction is timber structure. That's because it is cheap and easy to move timber - or even entire houses around - while it is expensive to haul and cast concrete and concrete prefab elements. A construction method is good when it is optimal for a specific location and the specific market conditions.
Reinforced concrete is ultimately the superior construction method for bridges but only if all the other factors are not included. There is a reason why the US build an extensive number of bridges in the early 20th century without concrete. It was cheaper, easier and faster and did the job. It is the reason why American infrastructure is failing now, but that's because American bridges were built like steel bridges but are maintained like concrete bridges.
Russia has plenty of infrastructure built in steel because of the same reason - it needed fast industrialization and steel was cheap and plentiful in USSR. The main construction method for bridges in Russia is therefore similar to that in the US - steel frame - and not as in China, Japan or Europe - reinforced concrete. It will be obvious when you compare density and age of human settlements in these places. While both start with stone and timber every place with long-term established urban networks will diverge into concrete and every place with fast growing dispersed urban networks will diverge into steel.
The ultimate purpose of a bridge is to allow transit over an obstacle for x amount of years. Whatever is cheaper is the better choice
Secondly China has other considerations that need to be included in bridge design - most notably earthquakes and wind loads in coastal regions.
global seismic hazard:
population density in China:
The reason why it matters is because when you reinforce steel structure against such forces as earthquakes (even weak ones) and strong wind loads it becomes more economical to develop certain types of reinforced concrete prefabricates. At certain economies of scale it becomes simply cheaper to build "more expensive" structures than to build "cheaper" ones especially if those cheaper structures will require excess maintenance. Here coastal regions with higher salinity play a huge role. Corrosion is much more intense and concrete is necessary to make maintenance viable. But if you only have one bridge to take care of it might not be a problem compared to when you have 100 bridges to take care of.
Another factor is size. China is big and populous so everything is big in China to accommodate the area and population. Russia is expansive but has relatively few people in that area. Chinese infrastructure is designed with high intensity of use and often resolves issues that put two huge centers of population and activity together. Russian infrastructure is mostly strategic - it enables people and goods to be moved from point A in the west to point B in the east. The only exception is Moscow (13m) and St Petersburg (6m) against 140m in all of Russia. All infrastructure in Russia is therefore necessarily smaller than in China and this also plays a role.
The strength of building materials is not scalable in the same way that geometry of the structural element is. There are certain loads and spans that work for cheap small prefab concrete structures and then when you move past certain size suddenly you need concrete elements double and triple the size and it is cheaper to design a monolithic steel element - even if it costs more - because it is smaller and you don't have to make everything else bigger. Then once you move past certain span and load it again becomes more practical to design concrete elements because steel is too problematic. The answer is - it depends.
Now put all these considerations together and remember that I only mentioned the most important ones.
Russia designed the bridge it knew how to design, build and maintain. It also built the bridge that was the cheapest and fastest to build. It doesn't mean that it's a bad bridge. It most likely is an "American" bridge meaning that it would require more maintenance over 20 years and in time would require modernization. But then again it might paradoxically be cheaper to replace older elements with newer ones for the next 20 years instead of making china-style concrete bridge for 40 years. Even things like financing and inflation can influence the profitability of a project over such timescales.
And as for the contractor - there is
very little difference between building long-range pipelines and building long bridges. The crucial part - the prefabricated main span - was ordered and installed separately by a sub-contractor. The foundations were made by a sub-contractor. The general contractor's main role is to organize all the sub-contractors and for that the company was more than capable.
Any fault in quality or execution has to do with technical culture or corruption among the staff. It has nothing to do with what the company's main service is.
The person on Twitter is comparing apples to oranges for likes and retweets. There are no real experts on Twitter. Now random people on SDF... that's another thing entirely!
