> Mr. Kilsheimer cautioned that it is common in construction for the final product to differ from drawn designs.
Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit.
The Hyatt walkway collapse (https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse...) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and nobody thought through the changes in terms of how it impacted loading. Result? 114 dead.
> On November 13, 2008, the NTSB released the findings of its investigation. The primary cause of the collapse was the undersized gusset plates, at 0.5 inches (13 mm) thick. Contributing to that design or construction error was the fact that 2 inches (51 mm) of concrete had been added to the road surface over the years, increasing the static load by 20%. Another factor was the extraordinary weight of construction equipment and material resting on the bridge just above its weakest point at the time of the collapse. That load was estimated at 578,000 pounds (262 tonnes), consisting of sand, water and vehicles. The NTSB determined that corrosion was not a significant contributor, but that inspectors did not routinely check that safety features were functional.[126]
There's a lot of redundancy built into modern construction, but if you remove some of it because it's cheaper to build, and other degrades over time from wear, well... at some point, there's nothing left.
It's going to be an interesting report to read, whatever the causes.
The Hyatt walkway collapse could be interpreted as you said, but I think the specific phrasing ("built another so it would be easier and cheaper to build") shifts the blame onto suppliers and manufacturers a bit too much. The wiki article states that the architectural/engineering firm signed off on the suggestion of their supplier/manufacturer. While yes, it's easy to point the finger at cost cutting, we should also remember the point of engineering. It's to problem solve under constraints, and saving cost is absolutely a valid constraint. It's also worth noting that the original, unmodified design was already under-strength (relative to code).
For I-35, the NTSB report indicates that the design itself was undersized.
Designs need to be be accommodate for imperfect (and sometimes somewhat negligent) manufacturing, but these two examples aren't the best given the relative impact of flawed design, or design/change control process.
Not really off the top of my head, especially in North America.
I suspect you if you really go through (https://www.osha.gov/construction/engineering) you'll find some good examples of construction time problems. By it's nature, the vast majority of these are going to be "during construction time", so it'll be biased. They're also typically smaller scale operations... but that's also reflective of reality. Most construction is not the scale of 100+ unit condo buildings.
From my skimming through it there's a pretty even mix of:
a) Designer dominant (note there are a significant number of so called "design-build" entities present as well).
b) Construction/contractor supervisor/company dominant
c) Construction/contractor crew on the ground dominant
The NTSB also has a set of building related investigations to read through. Unfortunately, I seem to be having problems figuring out their search.
This sounds similar to the Toronto stage collapse that happened. The design spec'd out 3" tubing, but such a thing didn't "exist" (in their inventory) and they used 2".
Don't forget the Challenger SRB failure. Flown outside of design criteria with known flaws. But each time the shuttle flew with and SRBs had burn through, it was taken to mean not that there was a problem, but that the behavior was "safe".
Knowing the extant nomenclature is useful in researching ideas / literature further. I'm often stymied because I don't know what things are called in certain domains. Psychology seems to be especially prone to this for me.
If the Hyatt walkway had been built as it was designed, I'm sure it would have worked fine. But was it realistic to build it as designed? The design called for something like 12 meters (12m is my estimate from it needing to span the 2nd to 4th floor) of continuously threaded rod. Is cutting 12 meters of continuous thread on one rod a realistic design? This is a real question, I don't know the answer but this seems suspect to me. Wikipedia says the reason the construction company changed the design is because they would have to screw the bolts past several meters of thread per rod and they thought such long sections of threading would be subject to damage during construction.
Obviously their "solution" was lethal. But the original presumably safe design seems impractical at best.
> Analysis of these two details revealed that the original design of the rod hanger connection would have supported 90 kN, only 60% of the 151 kN required by the Kansas City building code. Even if the details had not been modified the rod hanger connection would have violated building standards. As-built, however, the connection only supported 30% of the minimum load which explains why the walkways collapsed well below maximum load (Feld and Carper, 1997).
It is possible to cut a single thread 12 meters long, but it would be hard to position on the construction site.
I worked in a gear shop for 5 years, yes, threads that long can be done. I suspect it might have been cheaper to get a rolled thread in that length, rather than a cut thread. Rolled thread is likely to be stronger, as it is formed, and not cut.
The Hyatt Walkway collapse was a failure of communications, the problems actually building it as designed, and the importance of building as it was designed, weren't properly communicated. If anyone had the whole picture, and realized what had happened, it would have been fixed at construction time.
I read this and i think about the builder who ADDED rebar to Falling Water's cantilevered concrete. Wright was pissed, but I understand it's the only reason it's still standing today.
I'm not a fan of the "Hyatt walkway collapse" as a teaching tool. The mathematics is extra interesting. Not sure it's good for the design failure which people reference. More people die from bad insulation design each year, it's the boring stuff that matters.
The Hyatt walkway collapse was at a big dance party with a fair few people watching from above. Perhaps dancing?
The coldest is a bit after dawn. So the previous dawns should have stress tested it. It should fail when the stress is around maximum under this Hyatt peak theory.
Max rate of change of temperature is sunset and sunrise. Rate of contraction I'd expect similar?
I'm not sure AC would change the thermal mass of a building much. One cubic meter of air weights 1.2kg. Changing the concrete walls would be hard.
A drunk hitting a pole at speed in the carpark would fit perhaps. Drunkenness to an empty carpark would be high.
The building (and deck surface) will continue to radiate heat throughout the night on a clear night, especially with few obstructions like a waterfront building has. That's how crops can frost with airtemp > freezing, and why the guidance is to cover your plants. It's not to insulate them against convection.
Counterintuitively in this scenario, this effect is greatest when the wind is calm.
If the peak was actually a trigger, in a residential building 1am is about the start when the max people other than a party will be there (everyone back from clubs)
It's also approximately the time when the building will be coldest. If there were any thermal expansion/contraction issues, they would have been at a maximum near 1am. The thermal expansion and contraction of concrete and reinforcing steel are nearly identical, but the steel has much higher thermal conductivity and cools off far faster; perhaps something snapped under tension between concrete that was still holding heat from the setting sun and steel that had shrunk in the chill of the night.
Incidentally, that chill is also why the 'low battery' alarms on smoke detectors tend to vexingly wake you up in the middle of the night, rather than conveniently running out in the 16 hours a day you're awake, which you might expect to happen twice as often. No, it's not just a bias that causes you to remember waking up to smoke alarm low battery chirps but not hearing them in the daytime, the electrochemical reaction in the batteries happens more readily at higher temperatures. It's a different chemistry, but the same reason a lead acid car battery has a hard time turning a starter in the dead of winter. The sensors in the smoke alarm always draw the same few microamps of current, but when it's coldest in the middle of the night, the battery is less able to meet the demand, and wakes you from your sleep.
The 1978 Citigroup Center engineering crisis is a good teaching tool. The chair of my Uni's Mechanical Engineering department has gotten a good amount of engineering colleges (mainly Mechanical and Civil) to use it as an example/study for students first semester.
Yes, and there's also a decent history of structural failure, or nearly so, from that particular habit.
The Hyatt walkway collapse (https://en.wikipedia.org/wiki/Hyatt_Regency_walkway_collapse...) is one of the better known - designed one way, built another so it would be easier and cheaper to build, and nobody thought through the changes in terms of how it impacted loading. Result? 114 dead.
The I-35 bridge collapse was another case of "various safety factors were eliminated until the safety factor was less than one." https://en.wikipedia.org/wiki/I-35W_Mississippi_River_bridge...
> On November 13, 2008, the NTSB released the findings of its investigation. The primary cause of the collapse was the undersized gusset plates, at 0.5 inches (13 mm) thick. Contributing to that design or construction error was the fact that 2 inches (51 mm) of concrete had been added to the road surface over the years, increasing the static load by 20%. Another factor was the extraordinary weight of construction equipment and material resting on the bridge just above its weakest point at the time of the collapse. That load was estimated at 578,000 pounds (262 tonnes), consisting of sand, water and vehicles. The NTSB determined that corrosion was not a significant contributor, but that inspectors did not routinely check that safety features were functional.[126]
There's a lot of redundancy built into modern construction, but if you remove some of it because it's cheaper to build, and other degrades over time from wear, well... at some point, there's nothing left.
It's going to be an interesting report to read, whatever the causes.