Help me identify this water tank failure?
Help me identify this water tank failure?
(OP)
Can anyone offer any ideas as to how this failure has occurred in a water tank in the attached photos?
The tank construction consists of a GRP wall, with steel framing around the outside, presumably to provide lateral restraint to the tank. The framing sits on RC beams which are on a raft footing.
One of the steel columns has completely sheared through the RC beam and pulled away from the tank, bending the horizontal ring beam in the process. It is clear that the baseplate anchors where installed outside the beam reinforcement, significantly reducing the shear capacity.
On first appearance it looks like the horizontal pressure from the tanks has caused the failure, however the tank wall itself is still intact with no apparent evidence of stress in the seem connection. The client is certain that vehicle impact has not occurred, however I have my doubts. There is no evidence of impact on the steel column however.
does anyone have any thoughts?
Thanks in advance
The tank construction consists of a GRP wall, with steel framing around the outside, presumably to provide lateral restraint to the tank. The framing sits on RC beams which are on a raft footing.
One of the steel columns has completely sheared through the RC beam and pulled away from the tank, bending the horizontal ring beam in the process. It is clear that the baseplate anchors where installed outside the beam reinforcement, significantly reducing the shear capacity.
On first appearance it looks like the horizontal pressure from the tanks has caused the failure, however the tank wall itself is still intact with no apparent evidence of stress in the seem connection. The client is certain that vehicle impact has not occurred, however I have my doubts. There is no evidence of impact on the steel column however.
does anyone have any thoughts?
Thanks in advance






RE: Help me identify this water tank failure?
Has that been hit?
Can't see how the tank can affect that support.
A few more pictures would help.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Help me identify this water tank failure?
That is a possibility. I don't know what the beam end connection is though unfortunately. I've attached more photos
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
Seems more likely that the footing failed or was hit, and the column, without its foot, pulled the ring out.
TTFN (ta ta for now)
I can do absolutely anything. I'm an expert! https://www.youtube.com/watch?v=BKorP55Aqvg
FAQ731-376: Eng-Tips.com Forum Policies forum1529: Translation Assistance for Engineers
RE: Help me identify this water tank failure?
It looks like a tensile failure caused by water pressure, although impact is a possibility too. It was not adequately tied to the beam to resist any significant horizontal force.
BA
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
You beat me to it on that one!
RE: Help me identify this water tank failure?
Dik
RE: Help me identify this water tank failure?
Professional and Structural Engineer (ME, NH, MA)
American Concrete Industries
www.americanconcrete.com
RE: Help me identify this water tank failure?
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Help me identify this water tank failure?
All in all, destined to fail.
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
The column that failed seems to be on the outside.
It is feasible that the tank did expand when filled as the column seems to be in close contact with a vertical seam. Given that examination of the first photo seems to show a repair line then this column and foundation appear to be more prone than the others to failure of the concrete and column being pushed out than the others
I don't really understand why those columns are there, but maybe to support a platform on top of the tank? If so why place it so close to the tank.
If you look at the tank to the left, it seems to be a similar size, but has a much meatier connection of the columns to a slab, not a set of supports.
Was the tank actually installed 90 degrees wrong? i.e. those columns should sit on the much bigger beams on the left and right?? or were the beams cast 90 degrees out?? Stranger things have happened and then everyone just goes - Sod it put it on the bases, no one will know and nothing will happen???
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Help me identify this water tank failure?
I don't understand the system either, but it looks like these "columns" are on all four sides.
RE: Help me identify this water tank failure?
I think BA retired has it best - these columns appear to be an afterthought and were poured after the main supports
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Help me identify this water tank failure?
Hokie66 - at the top of the columns there is a series of horizontal ties connecting the columns together. all the other connections are fine, it is just that one column at the base that has failed.
I doubt that thermal expansion is a factor as there are a number of water tanks there in the vicinity (exact same construction) and only this one has the problem.a few of them do have some cracks at the end of the RC beams though indicating that the problem with the anchors is consistent.
I'm still at a loss though as to why the column would push out that far and how the horizontal beam has deformed the way it has.
RE: Help me identify this water tank failure?
One condition for this to be true is that the tank was not empty at the time of the failure, and that, when clarke1973 visited the tank, it had been already emptied.
Now of course many questions will arise, for clarke1973, on the acceptability of the other beam supports and perhaps other bad details of this and other similar tanks.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Help me identify this water tank failure?
www.SlideRuleEra.net
www.VacuumTubeEra.net
RE: Help me identify this water tank failure?
The only thing to maybe check is to see if that horizontal beam which is deflected was actually or was supposed to be bolted to a beam running under the tank. Connection details on other tanks seem to show you build the beams like a complete box.
If you look closely there seems to be room for four bolts holding the beam/column to the base, but only two have been used.
you can just see in the first photo there is a horizontal beam under the tanks along the line of the concrete beam, but not clear how / if it was attached to the bent channel.
Lots to investigate!
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Help me identify this water tank failure?
It appears to me that the concrete beam that the column was attached to had been repaired in some fashion, judging by the difference in color each side of the diagonal crack visible in the first picture. I see no evidence of reinforcing steel emerging from the intact concrete. Perhaps a patch/repair was done after the original concrete was placed and was not properly tied to the original concrete and quite possibly was done with lesser quality concrete.
Ralph
Structures Consulting
Northeast USA
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
I wouldn't trust any of the anchorage at the bottom anymore. Seems an 'easy' fix might be take shear out of the anchors by adding tension struts or rods across the bottom to opposing vertical beams just like they did at the top. Doesn't seem like it'd be that hard to retrofit.
RE: Help me identify this water tank failure?
RE: Help me identify this water tank failure?
Looks to me like the horizontal beam was originally under the lip of the tank.