Wednesday, July 11, 2007

GLUE? This ain't no glue!

Maybe it's my problem that I expect too much from the NY Times, but this headline unnerves me to no end. "Collapse of Big Dig Ceiling in Boston is Tied to Glue". Do you thing they used the wrong bottle of Elmer's? (Dang, shouldn't have gone with the washable glue. From now on we use the regular white glue!)Even Forbes did better, calling out "Epoxy Creep" in its headline.


What I find really creepy are the comments about the civil engineering community. From the NY Times: "During construction, the builders tested the strength of the bolts; when some failed, the problem was attributed to installation errors, not breakdown of the epoxy. "The knowledge of the engineering community seems to be deficient,” said Bruce A. Magladry, director of the board’s office of highway safety. With concrete, steel and asphalt, he said, “once you test them for strength, they essentially keep that strength forever.”“Epoxy is not that way, it’s a different material,” Mr. Magladry said."

And from Forbes:"Magladry said there was no malice among those who built and oversaw the Big Dig."I don't think they understood creep at all," he said."Although the epoxy used in the tunnel had acceptable short term strength, it was incapable of supporting much lower loads over an extended period of time," Magladry said. "If any of the entities involved in the ceiling design and installation had considered creep as a possibility, a different epoxy or a different anchoring system would have been used."

It's a very sad situation. I would have expected that the failure was the result of some interaction of stresses, something more difficult to predict in advance, not a simple design flaw that was quite predictable.

This is the kind of system that we often test here at work. I wish they would have called us.

1 comment:

Gaussling said...

So, do you agree with Magladry that the epoxy failed as a result of creep?