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Miami Bridge Collapse

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  • Chet Ruminski
    03-20-2018 10:09:33 AM
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    There seems to be multiple considerations about the University Walkway Bridge collapse in Miami. There was a vertical tower that suspension cables would pass through that was not yet installed. A stress test was underway at the time of the collapse questioning why traffic was allowed to pass under. Question as to why there was no center support until the suspension tower was erected. A bridge engineer had left a phone message three days earlier about cracks appearing at one end but he didn't think they were a safety concern although needing repaired. Rubio has been to the scene of the collapse.
  • Dutch
    03-20-2018 10:44:27 AM
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    Chet Ruminski Wrote: There seems to be multiple considerations about the University Walkway Bridge collapse in Miami. There was a vertical tower that suspension cables would pass through that was not yet installed. A stress test was underway at the time of the collapse questioning why traffic was allowed to pass under. Question as to why there was no center support until the suspension tower was erected. A bridge engineer had left a phone message three days earlier about cracks appearing at one end but he didn't think they were a safety concern although needing repaired. Rubio has been to the scene of the collapse.
    Chet, from my point of view, it was a total "engineering" disaster. If you only look at the "weight" with also the top structure made from concrete as well sitting above the walking path as well the "span" then it is bound to self destruct. A simple "steel" structure with "arches" to pick up the load would have been a much stronger as well simpler design, which could have handled the load as well the span width.
  • Chet Ruminski
    03-20-2018 11:44:16 AM
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    I agree about the steel construction. The bridge was 14.2 million of a 19 million grant.

    As far as I know the bridge is three separate sections placed end to end , cables are passed through and then tightened to make one structure. I don't like it because of the huge mass of concrete that is held in compression without anyway of guaranteeing the integrity of all of the concrete that I know of. There was supposed to be a tower with suspension cables supporting the span that wasn't yet in place. Additionally the diagonals from the uprights in my opinion were pointed the wrong way for transferring load. They appeared to be in compression instead of tension. One article I read noted that the company made political contributions .

  • Dutch
    03-20-2018 04:01:06 PM
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    Chet Ruminski Wrote:

    I agree about the steel construction. The bridge was 14.2 million of a 19 million grant.

    As far as I know the bridge is three separate sections placed end to end , cables are passed through and then tightened to make one structure. I don't like it because of the huge mass of concrete that is held in compression without anyway of guaranteeing the integrity of all of the concrete that I know of. There was supposed to be a tower with suspension cables supporting the span that wasn't yet in place. Additionally the diagonals from the uprights in my opinion were pointed the wrong way for transferring load. They appeared to be in compression instead of tension. One article I read noted that the company made political contributions .

    Yes, great answer Chet !
  • Chet Ruminski
    03-21-2018 05:29:03 PM
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    Dutch, The bridge was only partially installed. The problem is the structure was two independent slabs. The bottom slab carried the load of both slabs. The diagonals supporting the top structure add no structural relationship to the bottom slab and appeared to be configured to transfer the load to cables and then the suspension tower. Apparently the lower slab was designed to carry the load of the walkway and foot traffic. In my opinion a reinforced structural slab cannot carry the load of a 174 foot span. The slab would have to be a beam to span 174 unsupported.
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