huangyhg

design & manufacture of concrete slab
i heard you structural engineers tend to have a little too much fun in some of these forums, so have at this one with no holds barred.
a little history...
i'm a mechanical engineer by degree, tool design engineer by trade. i work for a company that builds things that go boom . you guys, as the joke goes, make the targets & . well, it so happens that we need to build a target to test are things that go boom. in other words, i'm tucking tail in between my legs and actually asking the structural and civil engineers for help. i know, i'm insulting all the mechanical engineers out there, but this has to be done.
before anybody gets on their and tells me that i have no business trying to design/build this thing because of my experience... i know . we plan on contracting this thing out anyway. but seriously, it's just going to get blown up .
the project...
the government in all their wisdom has designed this target consisting of (4) pieces 5/8 thick steel that is 8" wide by 72" long. the target is square (72wide x 72tall x 8thk) and fillet welded at the inside corners. there are 8 lengths of #4 (.50" dia) rebar running horizontally and vertically, each. finally, this target is to be stood on end to be shot at.
the questions...
the big question is, how is this going to be constructed? since this project will be contracted out, i guess that is up to the contractor, but we want to get all our ducks in a row and have many of the possible questions answered up front.
(1) what temporary forms are needed to construct this beast?
(2) i have a tentative weight of 3650 lbs. access to the test area is limitted, so how can we pour the concrete in place (rather vague, i know) or move the final product? in other words, what hoist rings are acceptable (from whom) to carry this weight? i am looking into bolts from hilti in combination with crosby shackles because i assume we will have to pour the concrete in the "flat" position and tip it up on end.
(3) the rebar is not welded to the steel frame. if we bolt to the steel frame, will the steel frame hold? i can figure this out from a strength of material issue of the steel, but i don't know how concrete bonds to steel and how to consider the added concrete strength.
(4) should the rebar be welded to the steel frame?
thanks all for your unhindered responses and good senses of humor.
--scott
suggestion from another non-structural/non-civil type:
how about drilling 5/8" diameter through holes in the 72"x8" perimeter steel? cut the rebars long enough to have about 1/2" protrude through the holes. fillet weld the rebars to the frame on the outside.
for pouring the concrete, place polyethylene (visqueen) sheeting on a level concrete surface. set the frame on top, and pour the concrete using the perimeter steel as your form. trowl off the top and let cure. wait 28 days, then stand the sucker up and blast away.
swertel,
what you are asking for, structural engineers do every day. it is call "tilt-up construction."
yes , you need a flat surface (preferibly concrete) to pour the concrete targets flat. measuring 6' by 6', and weighing only two tons, the targets could be built any place and transported easily to their final destination.
williams form engineering corp, gateway corp (not the maker of computers), and others, sell inserts to be embedded in the concrete for hoisting the panels, and supporting them in place, if needed.
if the purpose of the 5/8 x 8 steel plate is to protect the corners of the concrete against the things that go boom, i would suggest to use 8" channel instead, for better protection.
the rebars do not need to be welded to the frame. rebars are difficult to weld. welded studs (3/4" diam. by 3-3/4" long studs at 12" on centers, per example) welded to the inside face of the channel would keep the steel frame tied to the concrete.
i assume you have studied what the energy of the boom thing would do to the concrete. you could find information about penetration of fragments into concrete in the army technical manual tm-5-1300 (

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