Bridge Collapse in Florida

[ADAguy]

What say you all to this disaster? All may not be as it appears, or not.
It appears that a support tower had not yet been erected. I haven't seen any pictures of the proposed bridge yet.

 

[my250r11]

https://www.thebuildingcodeforum.com/forum/threads/miami-bridge.22636/

This thread has some info.

 

[Sifu]

Gonna be a lot said about this, time will tell. It is hard to believe we saw this kind of failure in a major US city for a brand new bridge.

 

[cda]

Gonna be a lot said about this, time will tell. It is hard to believe we saw this kind of failure in a major US city for a brand new bridge.

Well technically it was not a bridge yet

 

[ADAguy]

In viewing the video I note that the collapse begins on the left side of the bridge. Look at it frame by frame if possible to see what gave.

 

[Thomas Silva]

I read somewhere that it was actually a truss bridge, and was a cable stay bridge in name only, as the cables and mast were to be added for aesthetic reasons. This makes sense as the horizontal element is not thin at all, and built like a box truss, even though it was for pedestrian loads.
If this is the case, note how the tension struts in the truss are configured in a very eccentric "sunburst" pattern, appearing to be aligned with the stay cables. This raises the question as to whether the eccentric truss configuration, acting as a simple-supported beam, contributed to the failure.

 

[cda]

Welcome T.S.

Another Californian

 

[Msradell]

TS: you are totally correct there were even cables connecting the mast to the bridge, they were only going to be pipes with nothing inside of them. They were going to add some minimal support to the bridge to help overcome harmonics when people walked across it. Here's an engineering form with lots of discussions on the topic: http://www.eng-tips.com/viewthread.cfm?qid=436595

 

[VillageInspector]

https://www.usnews.com/news/best-st...ey-design-change-stymied-bridge-cost-schedule

Interesting article

 

[conarb]

Henry Petroski, a Duke University civil engineering professor, said even seemingly minor changes in a bridge's design can lead to failures.

"Once a design is completed, subsequent modifications tend to be suggested and approved without the full care that went into the original design. This has happened time and again in bridges and other engineering structures," he said.

I think this applies to all construction, design changes have always given me headaches, just look at the infamous Berkeley balcony collapse, a woman on the Design Review Commission demanded that two balconies be added because it would look better, even though everything had been bid-out and there was no money for the additions.