51–60 of 75 posts
I think a fairly good argument can be made that the design of this bridge was novel to the point of being negligent as per https://www.youtube.com/watch?v=FSPI0xkTifI
The homepage of the "Norwegian Safety Investigation Authority" is much more informative and the 2 documents have interesting photos, e.g. closeups of where the wood broke. https://www.nsia.no/Road/Investigations/22-441 It does not state why they conclude the cause was overload, only that "Uncovering the technical causal factors for the collapse of the Tretten bridge has been challenging. The expert group has worked i…
The headline is misleading. They are saying that it seems to have failed due to some kind of mysterious fatigue failure at a wood to steel structural interface. The investigators are struggling to work out how because the timber was damaged when it hit bottom of the river and then damaged further when it was hauled out for inspection. The overloading in the headline seems to refer to the ‘load shedding’ to other stru…
[1]https://www.researchgate.net/figure/The-Perkolo-bridge-after...
>"... An overview of capacity models derived using the yield limit equations and following the European Yield Model (EYM) approach is provided in [20]. Major examples of structures collapse led by brittle failure in dowelled slotted-in-plate connections are the two trusses of the Siemens Sports Arena in Denmark [21] and the truss of the Perkolo bridge in Norway [22]. Uncertainty in the evaluation of connections' deformability is responsible for local damage in connections, and change of force transfer mechanisms compare to those considered in the design. ..."
Earlier quoted context omitted.
While the statement seems technically correct, it smells a bit disingenuous to me. Most sophisticated structures are engineered using load factors in combination rather than traditional strength design methods because it leads to more efficient use of materials and hence lower cost. Yes, strength design might require a 4x safety factor. That’s why engineering practice employs statistical methods and combined loads. K…
> If the structure relies on safety factors there’s a problem. Maybe I’m misunderstanding your point, but I don’t think it’s unreasonable to have actual (large) limits on what a structure can handle? Otherwise, everything will cost X times more time/money to build.
I’m a mechanical engineer and figuring out the appropriate strength a part needs, then making it twice as strong, is a common tactic. You can’t account for material differences, little casting voids, or just your math being off a little by the approximate methods we use to calculate stresses. The more perfectly we can model and then repeatedly destructively test a part, the closer we can get to a safety factor of 1.
Earlier quoted context omitted.
> Personally I would think that a bridge should be able to handle "A passenger car and a truck with trailer loaded with lime were on the bridge when it collapsed". The Norwegian Safety Investigation Authority seems to agree. https://www.nsia.no/Road/Investigations/22-441?iid=35881&pid... : “Checked according to the recommended calculation methods in today's current regulations for the design of wooden structures, the…
While the statement seems technically correct, it smells a bit disingenuous to me. Most sophisticated structures are engineered using load factors in combination rather than traditional strength design methods because it leads to more efficient use of materials and hence lower cost. Yes, strength design might require a 4x safety factor. That’s why engineering practice employs statistical methods and combined loads. K…
I know that isn't always a bad thing, but this is the kind of sentence that always gives me pause. In the case were over-engineering something to 10x minimum tolerance can be re-configured to be only be 8x minimum, then sure, that sounds like there's some room to safely redesign for efficiency/cost sake.
My pessimism for the world today tends to make my first impression the "lower cost" phrase being used is always the "cheap bastards looking to cut corners at the expense of safety".
I think a fairly good argument can be made that the design of this bridge was novel to the point of being negligent as per https://www.youtube.com/watch?v=FSPI0xkTifI
I can’t get really past the guy’s attitude. From the get go he’s mocking the work from the marketing to materials, and he’s not doing it in a fun way. Just plain denigrating. I thought you linked to B1M or something.
My dad is a retired civil-engineer and he displays the same type of mockery (and worse) when he sees badly built stuff. Because he very well knows that badly built stuff can cause people to, well, die. It's not "they made an ooopsiee, let's not make it worse by denigrating the designers/builders", it's "they really f.ed things up, people could have died, they're morons (and worst)".
I frequently cross the Golden Gate bridge. This is my nightmare. Can you imagine plunging to your doom if that bridge failed? Yikes!
[0] https://triblive.com/local/frick-park-bridge-collapses-natur...
I frequently cross the Golden Gate bridge. This is my nightmare. Can you imagine plunging to your doom if that bridge failed? Yikes!
Pittsburgh allegedly has more bridges than any other city in the world. One collapsed last January.[0] I had driven over and walked under it many times. An uncomfortable number of other bridges in the city are in poor repair.[1] If one of the bigger ones over one of the rivers here collapse, it will be a tragedy of similar magnitude to your nightmare. [0] https://triblive.com/local/frick-park-bridge-collapses-natur..…
It just doesn't really go anywhere except a couple thousand homes.
The big bridges on the three rivers, on the other hand! It seems to me that they're always always under repair.