Concrete reaches a substantial percentage of its design strength very early on. Certain admixtures can speed this process further. During new construction, forms can typically be stripped within a day and by 7 days the concrete reaches 70% of its final strength. You wouldn’t need to overdesign a building by a huge factor in order to take that into account if you need to use it immediately. That, plus International Building Code loading are already very conservative so unless they’re stacking bodies to the ceiling or storing heavy equipment immediately, you’re not going to see dangerous overloading even if the hospital is open for business early.
Combine that with the fact that these buildings don’t need a typical 70 year service life and will likely be abandoned before any long term issues set in.
That said, I’m certain corners are being cut. The scary thing about civil and structural engineering is how easy it is to take shortcuts and make mistakes without it being initially apparent. There’s a famous case study of a 13 story Chinese (what a coincidence!) apartment building that literally fell on it’s side because they undercut the foundation on one side and stacked the fill soil on the other.
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And this was ironically on the high-end of Chinese construction quality, since, as a government official hilariously pointed out after the collapse, “The building held together despite falling over”.
That did not change the fact that the wrong kind of foundation was used, it was underdesigned, and there were no competent geotechnical engineers around to point out that maybe building a 13 story building on grade then excavating down 20 feet right at its base wasn’t such a great idea. A combination of lack of experienced oversight and disregard for engineering principles make issues like this rampant. For comparison, a US developer can’t even
consider an unlicensed structural engineer or contractor; they wouldn’t even be able to get a permit to break ground. The Chinese construction firm responsible for the above disaster had been operating illegally for
5 fucking years, and the building owners
did not give a fuck.
Responsible parties were arrested after the fact, but that doesn’t alleviate the corruption of the system that led to the failure. This is a pattern that may be familiar to the people following the current crisis.
The Chinese construction industry is relatively young, and the institutional experience, while growing, is still low. Anybody who’s worked even adjacent to the American construction industry would tell you that your average American contractor is dumb as fuck. Their supervisors tend to be a little brighter, but even up to the structural engineer of record you can end up with people who are capable of making severe errors in judgement. That said, the emphasis on safety is extreme, and the system of oversight is robust. The kind of detailing errors that lead to truly deadly catastrophic failures are honestly few and far between (for new construction, poorly maintained, aging infrastructure is a discussion for another time). In general, you’re more likely to have someone in the chain of responsibility who has designed or at least seen a similar system.
Take that away, and reduce the education of every laborer and foreman by about 6 grade levels, and you get things like
70,000 (reported) casualties from a single earthquake.
It’s honestly harrowing to me that literally tens of millions of Chinese people are living in buildings that will
kill the fuck out of them in the event of a major earthquake. That’s a lesson the US learned in 1906 in San Francisco, and again in the early 2000’s. It’s an interesting cultural contrast.
