huangyhg

lateral pressure due to scrap metal?
scrap metal will lean against a 75ft(25m approx) rc cantilever retaining type of wall.
any information on lateral pressure exerted by this pile to the wall will be highly appreciated
respects
ijr

depending on the sizes of the individual pieces of scrap, you could assume that is approaches the internal angle of friction of that of a coarse gravel (say upto 40 degrees). couple that with an approximate value of the unit weight of the metal scrap (with voids), it could be looked at as a typcial retaining wall.
keep in mind that wind loading on such a tall wall may govern the design (when no scrap is present.)
...just some thoughts.
-zulak
ijr...this is an unusual one!!!
i think zulak's comments are on the right track, just that 40 degrees is a bit high as scrap metal does not typically "flow" in stockpiles. it comes close to staying where it is placed.
you have to be careful with the character of the scrap and if it has received any processing prior to this storage. as an example, some classes of scrap steel must be cut into 3-foot lengths or less prior them being purchased from intermediaries (resulting in a higher bulk density), while others may be of essentially any size (creating larger voids, lower bulk density).
secondly, steel has a unit weight of around 450 lbs. per cubic foot. this is compared to soil ranging from about 90 to 120 lbs.per cubic foot. other scrap metal (aluminum for instance, will be lower in unit weight), but again depending on the "particle size or piece size" will exert different lateral pressures due to changes in bulk density as well as interlock of the pieces that will tend to decrease lateral pressure.
"processed" scrap metal usually comes in mangled pieces ranging from 1" to 12" in diameter. once these pieces come out of the crusher, they are moved via conveyor belt and piled just like coarse gravel. the shape of the pile of metal assumes the shape a pile of gravel would.
now, if your piling axels and old water heaters against this wall, then thats a different story.
also, a 75' high cantilever wall sounds rather high. you'll probably need an extremely thick wall with probably #11's at 4" o.c.
you may i think use the coulomb's equation, only that beta angle is negative. real "inner angle of friction" should exceed 40 deg, but for the safety of the wall i wouldn't count but about 35 deg. so for a prismatic pile leaning against the wall, you could determine this way the active push. for specific weight once voids are accounted for i think about 2 tonne/m3 should be enough, but check (for iron metal stockpile i have a quote of 3 tonne/m3, and this definitely i think must be less). in any case check for the specific weight. compressed scrap iron briquettes are said bulk density 2.72 - 2.88 ton/m3 -must be us short ton- and much denser than scrap.
also take unto account that the horizontal push will be less at stockpile angles lower than the maximun; if such accumulation you think feasible count even horizontal surface for the strockpile. if on the contrary a half conical accumulation is that to be used, porting different profiles of pressure to a fem model of the wall should give some economy.

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