On Sunday 05 August 2007 22:17, R.C.Macaulay wrote: > The MnDOT critical inspection report of the failed structure is available > here: > > http://www.geocities.com/terry1094/I-35_Insp_Rpt.pdf > > Not a pretty picture. One note, officials have denied that the > resurfacing of the bridge had anything to do with the failure; so, you > know what *that* probably means. > > Terry > > Howdy Terry, > > Indeed, not a pretty picture. The bridge was a disaster waiting to happen.. > looking at Panel point # 13 west truss pic was enough for me. > > Richard > >
Does'nt anybody have a curious thought as to why this overhead decked beam truss bridge dropped straight down. Some 'authorities' mentioned a 'shift to the left', whatever that means; but the appearance from the direct overhead pic shown on CNN is that this thing was dropped straight down by litterally snipping truss members at the ends near the abutments. My engineering training leads me to guess that the taking out of, say, four tension members at the ends as in the vertices of a rectangle would have the thing fold up as so many loose scissors and drop straight like it did. These would have to have been 'loosened' at the same time so that no torsion forces would be allowed to dominate, giving the bridge the appearance of shear failure. The road deck was far too wide for my liking given the relatively narrow spacing of the parallel trusses, and that somebody, possibly an architect or a bean counter imposed his/her/their dream on unwilling design engineers to put this turkey out of the oven before it was cooked. In this way a large vulnerable target allowed in the words of the old rock tune: "Dirty Deeds Done Cheap!". Not to say that this WAS sabotage, mind you, for none would dare to suggest such a thing publicly! Can't scare the tourists, truckers, and commuters now can we? But then if such a thing just...fell...the law of averages wouid dictate a random failure of members, one at a time and not show favoritism either of tension or compression, nor of location. Look at a common old surveyor's textbook and see how they estimate and average errors. Surveyor's expect random errors to follow the law of averages. But if our 'experts' and spin docs are right, I just to to Atlantic City and put a sawbuck on the pass line of a dice roller and leave it there for a few hundred thousand rolls and dream of all the riches of the plug ugly old biddy setting the thrown of England. Standing Bear By the way, a couple of weeks ago, a natural gas terminal just 'blew up' in Dallas/Fort Worth right at the junction of a network of major Interstate highways. Did'nt do any real damage to the roads, but the incident did result in the closure of those roads while the gas cylinders were flying as rockets. What one wonders is whose son and heir approved such a dangerous facility in the proximity of a sensitive and militarily valuable road junction?
