She ran a modal analysis. The first five modes were ugly—torsion, sway, vertical bounce. But the sixth mode? A gentle, almost imperceptible lateral sway with a period of 4.7 seconds. That was the bridge’s “echo.” That was the frequency at which the old steel wanted to move.
Then she remembered the “echo.”
In the year 2041, the old suspension bridge over the Kaveri Gorge was scheduled for demolition. But Mira Nair, a young structural engineer, saw something different. She saw a ghost. sap2000 documentation