- 27 Ιουν 2016, 09:29
#272760
Μια παρόμια κατάσταση (όχι καταστροφική όμως) συνέβη και με την millennium bridge στο Λονδίνο
https://www.sciencedaily.com/releases/2 ... 080801.htm
https://www.sciencedaily.com/releases/2 ... 080801.htm
From the beginning, the bridge had two factors working against it: It was by design a flexible structure, and its natural frequency is close to that of human walking. From there, Strogatz says, all it needed was a relatively small crowd to spark the wobble.
"If the people are initially disorganized and random, if a few of them get into sync by accident, the bridge would become unstable," he says. With a certain critical number of pedestrians, the wobbling becomes marked enough to force everyone into stride -- thus compounding the problem.
And the critical number of pedestrians, tested subsequently on the Millennium Bridge and derived independently by Strogatz and co-authors, is as low as 160. An estimated 80,000 people crossed the bridge on opening day, with as many as 2,000 on it at any one time.
