How is the structural integrity of very old buildings, bridges, etc. tested to ensure suitable use by people, cars, etc?
In: Engineering
Civil engineer here. For old buildings, if they have the architectural plans then they can usually derive all the mathematical info they need and account for decayed members. If they don’t, they’ll try to generate one and usually schedule renovation. That’s mainly for old buildings like houses. Bridges can be tested for a variety of factors – they use a lot of deflection analysis, so like seeing how much a bridge will sag under a given load, or how much it’s cables (assuming suspension bridge) extend under that load. A lot of visual analysis occurs as well – cracks, rusty rebar, split timbers can all indicate the current state of the structure and can be accounted for in projections of how long it will last based on modeling. Other methods can also be used to look for wear *inside* a structure, like using electrical pulses or vibration feedback on concrete. Also, because building codes are so meticulous and regulated, a good inspector can actually refer to old building manuals and practically determine from those what kind of design life a structure was built for. It’s a fine-tuned skill and one of the aspects of civil engineering that is highly valued because of the experience it requires.
My timber design professor was such a knowledgeable guy that he was brought in to inspect why a frame holding a very expensive painting fell, and it didn’t even take him long to figure it out.
Honestly it’s pretty cool. Good question!
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