huangyhg

csp as a structural member
i'm a junior water guy -- does anyone have experience calculating failure modes of csp as a structural member? i'm using csp to protect/support a watermain across a bridge with piers spaced 4m apart. i wish to verify deflection in that span, and yield condition.
do i use wl^2/8 for max moment and 5wl^4/384ei for deflection? then how do i get my ultimate values?
thanks,
stan

and what exactly does csp stand for? is there a particular standard for it?
sorry -- corrugate steel pipe -- the steel code doesn't cover it, as it is not typically used as a structural
i have not looked thru this information, but perhaps the "corrugated steel pipe institute" offers guidance. here is a link
...or maybe the "national corrugated steel pipe association"
with a moment of inertia you could get an elastic section modulas sx by dividing "i" by the radius of the pipe. then you could check a service load condition, you will just have to assume some low allowable stress. maybe 20ksi or something unless the corrugated steel pipe institute tells you the steel type.
ultimate loads are a little tougher since you need zx or the plastic section modulus. this value is derived through integration.
i would suggest a service check as they are normally more conservative.
the bending and especially deflection formulas will be skewed because of the corrugations. you are not actually just tensile yielding the steel, but trying to elongate the corrugations. this puts the "outer fibers" in local bending as well. i would expect deflections to be much greater than with standard pipe of the same moment of inertia. one way to get around this is to obtain an e that is adjusted for this effect. the problem is, i would expect that e to be non-linear...
in addition to what swearingen stated, the corrugations will definitely affect the compression side of the pipe, i expect adversely. even though you can find material strength and section properties, you won't know how the corrugations will affect the local buckling of the portion of the pipe under compression. it won't be as simple as sigma = m/s.
what about trying to elongate or crush a finite piece of a corrugation like a plate of the same thickness? those two forces could be used as a couple moment. no quick check is going to yield accurate results. hopefully, conservative though.
there is always finite element analysis but i doubt you are wanting to put that kind of time in.
this is effectively pre-buckled pipe that you are talking about. it is not appropriate for use as a longutudinal
i think the water main will be supporting the csp

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