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  1. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Sym P. Lee correctly states: "The only thing more laughable than the reinforcement detail at the bottom end of Member 11 is that it wasn't the weakest link in the structure." This statement is correct because member 11 was loaded in compression. Concrete has considerable strength in...
  2. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Hi Hokie66 your comment "The issues with the design were that the form of the bridge as a concrete truss/frame of that shape and magnitude had never been done before, . . . " is not correct. The record is full of instances where concrete trusses were successfully used in bridges and other...
  3. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    One thing is certain. Everybody who saw the cracks just before failure was not qualified to assess them. Anybody who saw the cracks and who was qualified to assess them would have personally run into the road to stop the traffic passing beneath.
  4. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    When he says "Um, so, uh, we've taken a look at it," it certainly does not mean "I" have taken a look at it. Someone without qualification reported it. See below. The phone was destroyed for a reason. "Hey Tom, this is Denney Pate with FIGG bridge engineers. Calling to, uh, share with you...
  5. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    SF Charlie says: "I have said earlier that my respect of Figg dropped into the gutter when Figg was claiming the FIU bridge was still safe in the morning on the day when the bridge collapsed in the afternoon.:" Yes, but it is also clear that FIGG did not have anybody on site to assess the...
  6. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Hi Saikee Sounds interesting, but confusing. Any chance you can provide a plan view of the deck showing what you consider to be the vertical failure planes ? many thanks for your input.
  7. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Hi Saikee, much appreciated. But I have a question. Because failure is a three dimensional event, there must also be a vertical failure plane. Your excellent diagram shows only a failure plane in a horizontal plane - red line extending in an out of the page to form a horizontal plane...
  8. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Vance Wiley (Structural) -- I'm glad you agree that this node has no shear reinforcing at all.
  9. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Hokie66, you say that, "We are talking about a concrete truss/frame here, not steel, cast iron, wrought iron, wood, or aluminum." Hokie66, are you suggesting that because this truss is formed in concrete it is exempt from the requirement that EVERY truss/frame requires shear reinforcement at...
  10. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Nice point Waross. I quite agree. Hokie 66 says "Perhaps you can share with us an example of another structure of this type." Yes, every single truss/frame on the planet is a structure of a similar type. Every single truss/frame on the planet has got shear reinforcing at EACH NODE -...
  11. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    3DDDave == "This was a novel structure, and should have . . . etc." Not true. Trusses and frames have been around since before the middle ages. It is well known that both trusses and frames must have shear reinforcement at each node, where the forces in each element change direction...
  12. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Warros, you assert as a proposition: "Tension in the lower PT rod adds to the force on the connection." But this is wrong. By definition, the force "on the connection" is a force that is applied BETWEEN #11 and the deck. That means we are looking for a force OUTSIDE #11, that is BETWEEN...
  13. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    3DDave -- and the other three concrete trusses ?
  14. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    hokie66 -- been in the game for more than 40 years, but never seen these ?
  15. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    hokie66, I walk past this building every day. Ever been to Chicago? These concrete trusses can be found in just about every modern city. Sometimes they are concealed within the outer cladding of the building. Concrete trusses are well understood, and endlessly used.
  16. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    Hokie66 concluded that - "The design was fatally flawed, and hopefully will result in concrete trusses never seeing the light of day again." Hokie, I believe the correct conclusion would be that, "concrete trusses with fatal flaws should never see the light of day again." Concrete trusses...
  17. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    3DDave (Aerospace)3 Jun 20 01:05 SAYS: "No PT bars were sheared at the construction joint, at least not until the portion of the deck was cut loose for examination." Hi 3DDave. What is the inference that we can draw from this fact? Many thanks for your helpful input.
  18. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    3DDave (Aerospace)3 Jun 20 01:05 SAYS: "No PT bars were sheared at the construction joint, at least not until the portion of the deck was cut loose for examination." Hi 3DDave. What is the inference that we can draw from this fact? Many thanks for your helpful input.
  19. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    3DDave (Aerospace)3 Jun 20 01:05 SAYS: "No PT bars were sheared at the construction joint, at least not until the portion of the deck was cut loose for examination." That is correct 3DDave. That's because the PT bars were not connected to any other bars. They simply ended in 'space'...
  20. FortyYearsExperience

    Miami Pedestrian Bridge, Part XIV

    The horizontal component force in Strut #11 was known to be 1,500 kips (1.5 million pounds) at the time of the design Back of envelope, to hold 1.5 million pounds in place requires 25 square inches of steel. (before we get onto factors of safety etc.) NOWHERE in these drawings can we find 25...

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