ELI5: After watching numerous examples of buildings in Thailand swaying and appearing significantly damaged, what is the process for ensuring something so large, layered, and complicated is still structurally sound? How do they know what to fix and that the fix will be enough?
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The very basic first step would be to start at the bottom (the foundation) and work your way up and look at everything. Specifically you’re looking at the support structure. This would be load bearing columns and beams. Concrete and steel will both show stress fractures. You’d also look at joints where structural members come together. Welds will also show damage like cracking. Rivets and bolts might show separation or loosening. You’d also want to make sure everything is where it should be and not too far out of plumb or square. If you do find damage it would take a trained engineer to determine if it’s superficial or if and how it should be fixed. Different materials will exhibit damage differently, and when/if that damage becomes a concern really depends on the overall design and structure.
There are some more technical ways to look at damage too. Portable x-ray machines exist that are specifically meant for looking at structures like this. They are often used on more advanced materials like the composites used in wind turbines, but they can be used on steel and concrete too. Such machines can be used to see how deep surface cracks run, or to look for cracks and other defects that are not visible on the surface.
the first step is definitely a thorough visual inspection, checking for any obvious signs of damage or structural issues.
portable xray machines sound like a great tool for getting a deeper look at potential problems that might not be visible on the surface.
i imagine theres also some pretty sophisticated computer modeling that can be done to analyze the structural integrity and identify areas of concern.
at the end of the day tho, it takes experienced engineers to really assess the situation and determine what repairs are needed to make the building safe again. definitely not a simple process!