Edit post

Edit your reply below.

Post Body
Enter your post below.
[quote user="Overmod"]I have not looked at the 'accelerated' construction methodology carefully, but I immediately thought of the lesson taught by the flying-buttress failure at Beauvais Cathedral. [/quote] In this case the accelerated bridge construction means the concrete bridges was built on a nearby site. When finished it was transported like a pre-cast concrete element into its final position. Video: <a href="http://abcnews.go.com/US/explaining-accelerated-bridge-construction-technique-collapsed-miami-bridge/story?id=53777995">http://abcnews.go.com/US/explaining-accelerated-bridge-construction-technique-collapsed-miami-bridge/story?id=53777995</a> [quote user="Overmod"]This bridge was, I understand, intended to be cable-stayed.[/quote] Yes, the bridge looks like a cable stayed bridge: <a href="http://www.mcm-us.com/sites/default/files/styles/project/public/slider/east_view.jpg?itok=h0vYI120">http://www.mcm-us.com/sites/default/files/styles/project/public/slider/east_view.jpg?itok=h0vYI120</a> But I found a US Today online report that states that the bridge was a truss bridge. They pylon and the stays were just for show: <a href="https://www.usatoday.com/story/news/2018/03/16/miami-bridge-collapse-suspension-cables-support-tower/431418002/">https://www.usatoday.com/story/news/2018/03/16/miami-bridge-collapse-suspension-cables-support-tower/431418002/</a> Here are two quotes from the linked report: Cheryl Stopnick, an outside spokeswoman for FIGG Bridge Engineers, which designed the bridge, said the structure was “truss bridge with above-deck truss elements.” Robert Accetta, the National Transportation Safety Board investigator in charge, said diagonal elements between the bridge’s canopy and deck worked like a truss bridge. But the cables designed to fan out from the column weren’t needed to support the bridge deck, he said. “As I understand it, these were cosmetic,” Accetta said. “They were not structural members.” I don't know if this is correct but it would explain the otherwise odd building sequence. I have problems with the post tensioning process too. I would have aspected it was already done on the building site before final positioning. The location of the intermediate supports for the transport might have prevented the full tensioning though. Then I would have expected to keep the intermediate transport supports in place until the post tensioning is finalized. Or it was post-tensioned for its own weight on the building site and that worked for the transport too. So post-tensioning after final erection might have been added for the additional dead loads and live loads only. But that is monday morning quarterbacking. Will see what NTSB will find out. Regards, Volker
Tags (Optional)
Tags are keywords that get attached to your post. They are used to categorize your submission and make it easier to search for. To add tags to your post type a tag into the box below and click the "Add Tag" button.
Add Tag