MQ! - What if the sky falls down?, MQ? Have you ever feared such an event? No! Really NO? How about that one natural event that happens once in a 1,000 years (0.1% probability), or the 10,000 years event with only 0.01% probability? You know when that happens, all we can do is to pray to whoever, right?
Shortchanging cement in concrete is the typical means of cheating which happens all over the world - India, United States, China, etc. One Indian fellow told me about the time when she was helping in the expansion of her father's commercial building, and she had to watch like a hawk the concrete mix, to make sure they put the correct number of sacks of cement, and make sure it is cement and not flour or mud. The mix and the pour (placement) can be just as utmost important. All the correct amount of ingredients can be proper but if the mix is lousy, then sections of that poured concrete will have bad mix of very low strength. Lousy mix concrete can also absorb moisture that will corrode the rebars.
Construction inspection for quality assurance becomes very important and that's where concrete labs perform strength testing of the poured concrete from both concrete mix from each truck as well as from in-place concrete. In the US and specifically in reference to one runway of the Denver International Airport, they caught cheating by both the contractor and the concrete lab. The contractor was in a hurry to complete the work, so they poured a sizable amount of concrete on a portion of the runway with weak concrete and somehow the lab cooked the book (altered the test results) to help cover it. When the "draft" test result became available, but alas! there was already 10,000 cu yds (figurative number - not sure of the number) of that stuff poured, what options did the low bid contractor have? They chose to lie and negotiated something with the lab to cook the book. The lab was supposed to be an independent entity with a specific contract to ensure concrete quality, but still susceptible to cooking the books. This just shows you that an independent quality assurance contract can be susceptible to cheating, and that was in the good ole USA. It was not found out until after the contract was completed, and by another independent test of the in-placed materials. No life threating cheating here, just that a portion of the runway could be expected to deteriorate much sooner. In cases like this, the insurance company usually covers the damage, for the removal and replacement of that one section of the runway. No sweat, the insurance company just raised premiums on all insurance coverages to make up the loss.
There is also no assurance about earthquake resistance of the buildings in Kiwi land until a high magnitude seismic activity hits the island. I myself don't have faith with those high rise buildings in Las Vegas. If China's engineering uses Japan's or Singapore's seismic codes and criteria, then those buildings you saw in Shanghai and Beijing are as safe as humanly possible.
Now ... Do you think China and Chinese people don't have any compunction at all about life and death? You think they don't have any pride of their new infrastructures and their engineering? And you think Chinese engineers are just a bunch of crapolas? So you think Chinese are motivated by profits and money only, and don't have any honor nor self respect for their own professions? Do you know that the more complex and elaborate the structure, the higher the cost for design as well as construction? So you think Chinese hardly value the higher pay they get for doing complex and expensive work? Do you think Chinese don't have memory, so lousy design engineers and construction inspectors and foremen can just go from one building to the next, even as their just completed projects are falling apart and collapsing behind them? Do you think those Chinese engineers would take bribes and let their belovedly and proudly designed buildings getting built with toothpicks, chopsticks and mahjong stones, and let them collapse? You must be joking, right! Or, to paraphrase your famous statement "You don't understand!". So why do I always misunderstand you, MQ? You may say things in jest, but please don't make them sound so serious. It has nothing to do with Yiwu. She just tells it like it is, even if it is apparently "distateful?!" to you.
Seismic reinforcement of concrete columns (bridges), the vertical rebars need to be enclosed (wrapped) with smaller rebars cage, which is to provide confinement of the concrete. The purpose is to keep the crushed concrete confined in its place so the column would not collapse. That's the new seismic standard for bridges in California and the columns (piers) of all existing California bridges are required to be retrofitted. For retrofitting buildings, they usually use steel sheets enveloped around the columns. For new buildings, the primary columns would have spiral reinforcements. So if you saw those thick columns under construction and there are spiral reinforcements, then they are constructed properly.
On high or tall (more than 3 stories high) buildings, the primary structural members are steel beams for flexure and one specific concrete member (usually elevator shaft and stairways) for rigidity and to resist shear. All other concrete looking members and interior walls are architectural. So buildings may not and are unlikely to collapse but many of the panels can. How those panels are tied down become critical. I think it's easy to cheat on this, but not where labor is so inexpensive. Where labor is expensive, the installation cost becomes a very big deal whether panels are placed in one day or two days. Where labor is cheap, are you kidding me???? They may as well double the installation laborers since they get plenty of overhead profit from the more expensive materials. Those panels can be susceptible to fall down. Guess who are the unlucky ones who happen to be in the path of the falling panel? Just about anybody inside the building or outside on the sidewalks and streets.
By the way, properly designed and constructed seismic resistant building is only as good as the previous nastiest earthquake. No building is totally and completely seismic proof. No one build anything to resist that future real nasty earthquake that can happen tomorrow or a thousand years from today. When the next seismic activity is just one notch (but that's exponential) meaner than the previous one, then all bets are off. Those buildings and most of the infrastructures in the east coast USA are not seismic resistant structures at all.
Don't forget fire and means for escape, excluding windows. Hopefully those stairways are fireproof with adequate ventillation.
Are the buildings in New Zealand been retrofitted or upgraded to resist the most plausible earthquake? Have they been retrofitted for fire protection?
MQ dude!, you talk like all buildings in NZ and your most highly esteemed elsewheres are constructed like the Pentagon. Heck, they are not even built like the hospitals. |
