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Re: big dig structural failure - epoxy anchors overhead supporting gravity

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From: WSawruk(--nospam--at)absconsulting.com : I would expect that the engineers designing the tunnel roof would have considered the dynamic effects and sized the concrete panels such that the panel dead weight would not be exceeded by the pressure wave in order to keep the hangers in tension and to prevent impact loads when the panels drop down.

Show me the calculations these engineers did to consider that. If they can't, they were not done.

Regardless, there still would have been a time variation of the tension load on the anchors (always in tension but varying with time with each pressure wave) and I'm wondering if this type of anchor is suited for such loading conditions.

Was it tensile failure or shear failure? Are design practices for metal fatigue also applicable for epoxy? The bond between epoxy and concrete? Between epoxy and the anchor? What about relaxation or creep? These effects may not need any cycling loads to cause problems.

I'm sure legal wise the argument that the design and construction met all legal requirements will be made, implying that the designers and constructors are not liable. If so, were these legal requirements sufficient to prevent such a tragedy? If not, who should be prosecuted? The code writers, for failing to provide adequate legal requirements? The regulators, for failing to sufficiently vet the code they decided to enforce? The designers and constructors, who should not have trusted the integrity of the regulatory requirements? I'm sure there are other entities that I haven't mentioned that are at risk.

This situation brings up a lot of issues, both engineering and public policy, which will probably be inadequately answered. What's sad is that a lot of taxpayer money was spent for a public facility no one can use, at least one body has shown up, and gave the trial lawyers something to do over the next couple of years. The end result will probably be pragmatic iinstead of principled.



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