huangyhg

brooklyn bridge why design cords as continous beam?
why did john roebling design the truss to have longitudinal top and bottom chords as continous?
see picture here
how do you know that the design was modeled as continuous? if the joints develop restraint, then the continuous model may be conservative with bending included in the chords.
in a book by mccullough it says "the inclined stays would have a strength of 15,000 tons,enough to hold the floor by themselves.if all four cable were to fail , the main span would not collapse.it would sag at the center but would not fail"
i am guessing this is why the top beam and bottom beam is continous.(the picture i linked to shows the moment splice)
anyone agree or disagree?
design trusses with hinged joints also would not fail if interior supports are removed. no moment connection shown when i opened the picture, just cables and road deck.
suspension and cable stayed bridges require longitudinal stiffeness trussses. hence the chords would have to be continuous
kelowna: why? i don't fully follow your logic, however am happy to expose my ignorance for the chance to learn something. i fail to see why longitudinal stiffness could not be acheived with a fully panel point pin-connected truss. care to elaborate?
cheers,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
sorry youngstructural
i misunderstood the posting and you are, obviously right, a pinned connection truss would achieve the required longitudinal stiffeness.
my apologies
no stress; we all have those days!
cheers,
ys
b.eng (carleton)
working in new zealand, thinking of my snow covered home...
re
i guess "back in the day" they had pretty deep pockets too ... they were using this new fangled "steel" stuff and didn't have the tools or maybe the knowledge to "design" an efficient structure, as the comments about all four support cables breaking wouldn't cause the bridge to fall. personally i'd question that one alittle, and with today's tools we could prove it one way or another ... i'm sure that the load case (for the failed structure) would be significantly less than the intact loads.
this is not to say that they didn't biuld a very good bridge that is carrying much higher loads than could ever have been imagined in the day. how will our "efficient" structures hold up in comparison ? what would a bridge built to code look like ??

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