" Would it not be prudent for scientifically trained people to...

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    " Would it not be prudent for scientifically trained people to gather all the facts before going off half cocked. "


    Amin Heidarpour, who is the head of Monash University's Structural Engineering Group, said only a thorough investigation could provide a definitive explanation, but "fatigue loading" from the wind was a likely factor.

    "[It] may cause fatigue in the bolts, in the connections, in the structural elements itself, and fatigue may cause some kind of a micro-crack in these elements, such that one strong wind happens and that micro-crack can become a real crack," he said.

    "The sign has been supported from one side, while the other side, the top side, is free.

    The sign was attached at its base to a gantry or frame, with the rest of the sign sitting above the frame

    Some other freeway signs in Melbourne are attached at the centre of the sign, which Professor Setunge said would halve the wind pressure applied to the sign over time.

    "When you have a connection in the middle you have better stability, when you have the connection at one end, the whole force of the sign, or weight of the sign is on one side," she said.


    "As long as the connection is designed for that condition it should be fine: so this all comes down to what load the connection was designed for, whether the connection was installed correctly during the construction stage, whether there has been good maintenance practice where you monitored the connection over a period of time to ensure it does not shown signs of distress."

    She said the three most likely factors based on the information available were:

    • incorrect calculations of the number of cycles of wind pressure the sign would be able to withstand over its expected design life
    • undetected corrosion of the sign's connections
    • an error during the construction and installation stages
    Other possible causes for the failure of the sign's connections were the original design and installation and poor maintenance checks, she said.


    https://www.abc.net.au/news/2019-01-16/melbourne-tullamarine-freeway-sign-what-caused-it-to-fall/10712782


    The only constant in all of this is, the wind.


    https://www.huffingtonpost.com.au/2017/08/02/watching-these-planes-land-in-100-km-h-winds-in-melbourne-is-ter_a_23060708/


    Raider

 
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