Quality stuff, proving to be extremely useful for one of my university assignments

This program showed why Millennium Bridge wobbled, and now I (a Yank) know why it wobbled. It was explained in a way I understood it, non-technical. I have empathy for the engineers who were outside the normal bridge design realm (or box) and fixed the bridge in a elegant, simple way, but I know those engineers scratched their heads and crunched some numbers to make it look easy. Excellent show, I learned something, Adam Hart-Davis did a first class job in presenting it.

Skip to 2:42 to see the actual show described in this video's title (and not BBC ads from 2 days less than exactly 5 years ago (comment posted Nov 3, 2016)).

A great video.

Video starts at 2:40

They should have studied soldiers on the march and sailors at sea.

@martentrudeau6948

6 жыл бұрын

alpha18412 -- The reason for the frequency problems occurred is because the suspender cables were hung at a low angle, not normal for bridges, this was a bridge like none other. If it had been a more conventional design they would not have had that problem. The engineers said were surprised and maybe embarrassed too, but nobody had built a bridge like that before.

Let's face it as a bridge it was badly designed.

Come on winder woman

@BagOfToenails

3 жыл бұрын

Will do

I really cannot understand what this fuss is all about as the answer to all this is quite simple, and all we have to do is to understand how a two legged human walks on a solid ground. Well, since a stationary person has two legs then for stability and in order not to fall the centre of gravity must fall in a position on the ground located between his legs. Now in order to walk forwards, a person does not simply lifts one leg but he firsts moves sideways so that his centre of gravity falls on the footprint of the leg that is still on the ground. This shifting sideways of the body is very necessary before one lifts a foot to take a step forward. IN fact a person can stay with one of his feet raised off the solid non moving ground as long as he retains his centre of gravity on the stationary footprint. When he steps forward and places his foot on the ground, then he proceeds to shift sideways to move his centre of gravity to fall on the footprint that touched the ground before lifting the other foot. Now when one people was walking on the bridge, he needed to keep his centre of gravity on either one of his feet when the other foot is raised. Since the ground is moving then the person would feel the move and he would react with the lifted foot in such a way that he would lower it in a position in which he anticipates that his centre of gravity is falling to .

@carmelpule6954

7 жыл бұрын

To continue with the above, that is the reason a person opens his legs as the ground under him is moving sideways. Now the rhythm is common to all people and so eventually, the whole crowd would be subjected to move to ensure that their shifted centre of gravity does not go unstable and they will fall. This fraternising due to the common movement of the ground will cause a synchronising effect on the forces on the bridge which will be related to the resonance effect of the bridge as it is the bridge which is deciding the rhythm and not the people who are falling at the same time and they are reacting to the fall all at the same time. That is the solution to this problem of swaying together. The bridge will not wobble if those four supporting cable on either side of the bridge were made not to run parallel with each other as this will have the effect of turning a catenary bridge which had parallelogram and no triangles into a cable stayed bridge with triangles in it. I covered this somewhere else so I shall not repeat it. The designer should have known that with so many squares and parallelograms in that structure, oscillations are to be expected................ he did not introduce triangles and that bridge is behaving like the Takoma Bridge mode of oscillation.

My first comment ever on youtube. The science is good but some of his comments during the show and then ending up with the comment 'winder woman" and the final words for the dancers at the end were not in nice taste at all. Certainly won't be watching him again.

@JohnWatkinsUK

6 жыл бұрын

I would encourage you to watch more from Adam Hart-Davis. He has made many fantastic series and has an engaging presentation style.

@Weird.Dreams

5 жыл бұрын

Your first comment? What do you want a fucking medal?! Just fuck off.