Question

explain why bridges are declared unsafe after long use
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Answer 1

When a bridge is used for long times. It lises its elastic strength. Therefore, the amount of strain in the bridge for a given stress will become large and ultimately, the bridge may collapse. That is why the bridge are declared unsafe after long use.

Answer 2

Answer:

Due to which the amount of strain in the bridge for a given stress will become large and ultimately, the bridge may collapse. This may not happen, if the bridges are declared unsafe after long use.