San Francisco Bay Bridge.
San Francisco Bay Bridge.
(OP)
When was the last time you drove down the highway without seeing a commercial truck hauling goods?
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San Francisco Bay Bridge.
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RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
The only way to prevent the fatique phenomenon was to pre-tension the whole assembly to make it behave as a block,reducing the stress range below the treshold.
RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
Respect the rectangular outfit of the reinforcement it is clear that built friction by prestress of the rods must have derived as viktor implies rhomboidal configuration upon the hinge rotational excursions, then entailed very localized action upon likely significantly prestressed rods (to share the load from the start). So a purportedly indiferently stable equilibrium was not since 1st difficult to actually be equilibrated and then upon real small separation of the notional equilibrium concept falls apart from such intended state and becomes unstable upon growth of stresses not devised (it seems enough) on the solution.
More, an interesting observation about the commonality of languages. It could be said that friction here entails pinching action, in spanish would be said, implies "acción de entalla". Entails means to be drawn, "arrastrar" in spanish, and "acción de entalla" means the pinching action at cleavage points. So in the past some people must have seen many ropes to fail just on this grip-grip movement. Anyone, not only engineers, have much to learn about situations by only understanding how something is described in the most ordinary language. Words, apart of the generalized current meaning have usually 3 or more deep levels of meaning that convey in subtle ways in-built knowledge as pertaining to the related matters.
RE: San Francisco Bay Bridge.
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RE: San Francisco Bay Bridge.
Having said that, it is true that the set-up seems poor to me and there is no way to guarantee an equal distribution of loads between the four rods. It would be interesting to know the stressing sequence and how the jacks were connected (parallel?).
Afer stressing anything as simple as sunshine in one side and not on the other would increase the stresses unevenly. I am not sure fatigue would be it. As complete elucubration, my bet would be for overstress on one of the rods.
Interesting observation about languages Ishvaaag. No two languages are alike. I am still seeking a good translation for 'accurate' in Spanish, somehow I feel 'preciso' does not have the same connotations.
RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
BA
RE: San Francisco Bay Bridge.
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I would think traffic should be kept off the bridge until the eyebar has been replaced.
There was rust inside the crack, so it had been there for a while. The last inspection was two years ago and the crack was not found at that time. Seems to me there should be more frequent inspections.
BA
RE: San Francisco Bay Bridge.
Regarding the last inspection not detecting the crack, that does not mean it was not there. An visual inspection is just that, a good look at the bridge.
I agree the bridge should be closed until the eyebar is replaced. On the other hand I am sure there will be huge political pressure to open it as soon as possible.
RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.
The cracked eyebar was found in September. This is not a problem of undetected eyebar cracks.
The cracked eyebar is still in place, even after the failure of the repair. This is not a question of "if only they'd found the crack in time".
The repair, as I understand it, was meant to be temporary while they figured out how to go about repairing the eyebar. It's 1930s steel, forged, unknown metallurgy. I asked someone smarter than me why they wouldn't just replace it with a new one, and it was pointed out that taking apart a joint like that is a serious engineering undertaking. So that means welding it, if they can. Or some other kind of bypass, along the lines of this repair they just did.
Interesting links about the new repair:
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RE: San Francisco Bay Bridge.
RE: San Francisco Bay Bridge.