[skeptoid]

I guess they didn't have resonance problems on the Golden Gate Bridgewalk "87 when: It is estimated that nearly 300,000 people surged onto the roadway. (scroll to bottom)

The arch of the roadway flattened out!
To see how visible the flattening was link to the full size at flikcr. (click "all sizes")

[Robert A Cook PE]

Per sq foot, people-wedged-against-people weigh more than the usual maximum traffic load of truck-behind-truck-behind-truck: the removal of platform weight (the concrete being scraped up and trucked off as construction/repaving continued removed even more weight.

So weight (by itself) wasn’t a cause, but removing the concrete from the surface seems to have reduced platform stability. The platform became less rigid as the concrete deck got thinner, and so the platform shifted (or moved the pins off their support at one end of one platform.

Then, as soon as one end of one plate was free (or had wiggled too far - the construction crew said the entire deck was getting more and more mobile as the concrete got thinner) the other concrete decks were able to fall. Then, the whole structure came down because it was not locked in place at both ends of every deck section.

My opinion? The connections (of one deck platform) must have failed first, as you can tell because the individual decks and beams came down in complete pieces.