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Gauri Chandore
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Joined: 23 Dec 2015
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 Posted: Thu Jan 23, 2020 6:30 pm Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Depending on the shaft failure on the middle, generally suggests local buckling. In this scenario, mainly the failure might have occurred due to weak concrete mix than anticipated during the design.
Sent from my iPhone
[quote]On Jan 23, 2020, at 11:27, indutridibesh <forum@sefindia.org> wrote:
 Here is a link to the complete videohttps://youtu.be/vUEhqlBTCqo
The circumferential crack in the shaft is clearly visible from some time ahead of collapse. The crack might be due to inadequate reinforcement and/or weak joint in concrete as well.
If the shaft wall is thin enough in proportion to its diameter, then the wall would wobble and it may fail when there is bending of the shaft.
On Thu, 23 Jan, 2020, 14:27 uhvaryani, forum@sefindia.org)> wrote:
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dipankar_deyandassociates
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Joined: 13 May 2017
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| Posted: Thu Jan 23, 2020 7:30 pm Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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I think the tank has some structural failure issue i.e.stabilty issueSo I think to conduct required NDTs on the tank
If it is possible to oversee the structure it will be solved
Regards
Dipankar Dey
On Thu, 23 Jan, 2020, 23:11 RAMARAJ S, <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote] Dear Uhvaryani, What is the condition of Tank, I mean fully filled or partially or empty? What is the dimension of Tank? If you have any structural drawing, Kindly produce for analysis
On Thu, 23 Jan 2020 at 14:28, uhvaryani forum@sefindia.org (forum@sefindia.org))> wrote:
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mohd_arastu
SEFI Regulars
Joined: 21 Dec 2011
Posts: 23
Location: Delhi
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| Posted: Fri Jan 24, 2020 4:30 am Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Hi
In my opinion it is a planned collapse of the tank. The concrete at the mid height of the tank was cut when the tank was empty and then filling of water have started to increase the axial load on shaft. As the load increased, the rebars exceeded their axial capacity which results into the collapsed of tank.
On Thu, Jan 23, 2020, 10:56 PM indutridibesh <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote] Here is a link to the complete videohttps://youtu.be/vUEhqlBTCqo
The circumferential crack in the shaft is clearly visible from some time ahead of collapse. The crack might be due to inadequate reinforcement and/or weak joint in concrete as well.
If the shaft wall is thin enough in proportion to its diameter, then the wall would wobble and it may fail when there is bending of the shaft.
On Thu, 23 Jan, 2020, 14:27 uhvaryani, forum@sefindia.org (forum@sefindia.org))> wrote:
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hemraj chanchal
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Joined: 09 Jul 2018
Posts: 9
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| Posted: Fri Jan 24, 2020 5:30 am Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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On Thu, 23 Jan 2020 at 23:11, RAMARAJ S <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote] Dear Uhvaryani, What is the condition of Tank, I mean fully filled or partially or empty? What is the dimension of Tank? If you have any structural drawing, Kindly produce for analysis
On Thu, 23 Jan 2020 at 14:28, uhvaryani forum@sefindia.org (forum@sefindia.org))> wrote:
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hemraj chanchal
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Joined: 09 Jul 2018
Posts: 9
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| Posted: Fri Jan 24, 2020 5:30 am Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Dear Sefians, It's true and I agree with the statement given by the madam Sangita Vij. Also, I request that the ratio provided and the shaft wall thickness.Hemraj Chanchal
M/s Sukhmandar Singh & associates
Amritsar
On Thu, 23 Jan 2020 at 17:36, sangeeta_wij <forum@sefindia.org (forum@sefindia.org)> wrote:
| Quote: | Yes, local buckling could be a reason, and it will be helpful to know the diameter of the shaft as well as the size/shape of the top .In any case, 1893 Code for Tank design has changed quite drastically, and it will be nice to carry out a check of all existing elevated staging tanks based on that.
Best Regards
Sangeeta Wij
President,WISE India
Managing Partner
SD Engineering Consultants LLP
Vice President(North),Indian Association of Structural Engineers,
Fellow and Chartered Engineer, Institution of Engineers
H333 New Rajinder Nagar(Lower Ground Floor),
New Delhi-110060
Ph:9811776210;01145128530
From: uhvaryani [mailto:forum@sefindia.org (forum@sefindia.org)]
Sent: 23 January 2020 14:26
To: general@sefindia.org (general@sefindia.org)
Subject: [SEFI] Failure of overhead water tank,at BANKURA,WEST BENGAL
Dear Sefians, Recently,a failure of an overhead water tank,supported on a reinforced concrete shaft of 150 mm thickness and of height 7.5 m has been reported in the media.
The shaft broke at about mid-height.What could be the reason of this failure?
Earlier cases of failure of these structures showed sinking of the shaft in the ground.In the present case soil is reported to be good, so the shaft has broken into two parts.I request our senior members to consider this case and give us the reason of this failure.My view is that the shaft thickness of 150mm is in sufficient and this has caused local buckling of the shaft.
with best wishes and regards,
uhvaryani
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alpa_sheth
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Joined: 26 Jan 2003
Posts: 264
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| Posted: Fri Jan 24, 2020 7:24 am Post subject: Re: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Dear Er. Varyani:
I agree with you. I too have personally reviewed multiple such shaft failures of overhead water tanks in gravity load condition, without any earthquake event. Bankura lies on the cusp of Zone II and III, hence in relatively low seismic zone. Additionally, no seismic event has occurred to be blamed for this event. So we need to focus on failure of such tanks in gravity loads since this is not a rare phenomenon. IS 11682:1985 was ratified in 2003 without change in min shaft thickness (150 mm).
I am of the opinion that the min thickness of 150 mm seems to be rather less. Most times the shaft failure appears to be initiated at the cold joint or at "lift" junction. That is not to say that the cold joint is the trigger of the failure but it is the weakest spot at which the failure gets initiated. The failure location is typically in the lower third lifts of the shaft. I think in the video shared by "indutribidesh", the initiating tension-flexure crack in the shaft was at lift junction at one third height (or thereabout). We get a view from just one side so can't say if the circumferential crack is along the full perimeter but my guess is that it must be. I also am guessing that the crack must have been a through crack, extending across the 150 mm thickness.
Such thin wall shafts have little flexure capacity and can fail with even minor accidental flexural stress. That could perhaps have happened, is my conjecture.
best regards,
Alpa
| uhvaryani wrote: | Dear Sefians, Recently,a failure of an overhead water tank,supported on a reinforced concrete shaft of 150 mm thickness and of height 7.5 m has been reported in the media.
The shaft broke at about mid-height.What could be the reason of this failure?
Earlier cases of failure of these structures showed sinking of the shaft in the ground.In the present case soil is reported to be good, so the shaft has broken into two parts.I request our senior members to consider this case and give us the reason of this failure.My view is that the shaft thickness of 150mm is in sufficient and this has caused local buckling of the shaft.
with best wishes and regards,
uhvaryani
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RKBhola
SEFI Member
Joined: 05 Dec 2009
Posts: 14
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| Posted: Fri Jan 24, 2020 8:30 am Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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At 4:05 of the video, you can actually notice the concrete getting crushed and spalling off - so construction quality may be a problem too.
RegardsRK Bhola
Civtech
New Delhi | Bengaluru | Punjab
On Thu, 23 Jan 2020 at 14:26, uhvaryani <forum@sefindia.org (forum@sefindia.org)> wrote:
| Quote: | Dear Sefians, Recently,a failure of an overhead water tank,supported on a reinforced concrete shaft of 150 mm thickness and of height 7.5 m has been reported in the media.
The shaft broke at about mid-height.What could be the reason of this failure?
Earlier cases of failure of these structures showed sinking of the shaft in the ground.In the present case soil is reported to be good, so the shaft has broken into two parts.I request our senior members to consider this case and give us the reason of this failure.My view is that the shaft thickness of 150mm is in sufficient and this has caused local buckling of the shaft.
with best wishes and regards,
uhvaryani
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KRISHNA PRASAD
SEFI Member
Joined: 24 Jan 2020
Posts: 1
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| Posted: Fri Jan 24, 2020 12:30 pm Post subject: How to apply vertical earthquake load |
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Sir I have a problem to define vertical earthquake load on etabs. Can you please help me to solve this problem.
sincerely
Krishna
On Fri, 24 Jan 2020, 17:14 hemraj chanchal, <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote] Dear Sefians, It's true and I agree with the statement given by the madam Sangita Vij. Also, I request that the ratio provided and the shaft wall thickness.Hemraj Chanchal
M/s Sukhmandar Singh & associates
Amritsar
On Thu, 23 Jan 2020 at 17:36, sangeeta_wij forum@sefindia.org (forum@sefindia.org))> wrote:
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slsindia
SEFI Member
Joined: 02 Jul 2014
Posts: 7
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| Posted: Fri Jan 24, 2020 12:30 pm Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Dear All,
This happened after two years of operation.
with regards,
C SUBRAHMANYAM
CHIEF CONSULTANT
SLS STRUCTO MECH CONSULTANTS
49-18-20, SREENILAYAM, LALITHA NAGAR,
VISAKHAPATNAM-530016
Ph/ Fax: 0891-6677145
MO: 9849598424; 7306754857
On Fri, Jan 24, 2020 at 5:18 PM mohd_arastu <forum@sefindia.org (forum@sefindia.org)> wrote:
| Quote: | Hi
In my opinion it is a planned collapse of the tank. The concrete at the mid height of the tank was cut when the tank was empty and then filling of water have started to increase the axial load on shaft. As the load increased, the rebars exceeded their axial capacity which results into the collapsed of tank.
On Thu, Jan 23, 2020, 10:56 PM indutridibesh forum@sefindia.org (forum@sefindia.org))> wrote:
| Quote: | Here is a link to the complete videohttps://youtu.be/vUEhqlBTCqo
The circumferential crack in the shaft is clearly visible from some time ahead of collapse. The crack might be due to inadequate reinforcement and/or weak joint in concrete as well.
If the shaft wall is thin enough in proportion to its diameter, then the wall would wobble and it may fail when there is bending of the shaft.
On Thu, 23 Jan, 2020, 14:27 uhvaryani, forum@sefindia.org (forum@sefindia.org) (forum@sefindia.org (forum@sefindia.org)))> wrote:
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nurat
SEFI Regulars
Joined: 28 Apr 2012
Posts: 22
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| Posted: Fri Jan 24, 2020 12:30 pm Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL |
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Dear Sefians,
On closely watching video my observations are as follows
01. It appears the failure is not in a middle of shaft.
02. No sign of buckling at middle of Shaft.
03. It is definitely Constructional Defect, during Construction they might have stopped the work for some time at he point of fracture and then started work again after big interval with out much precaution for Joints resulting improper Bonding.
04. There is chance of differential settlement in Foundation. By looking at field around it appears soil is soft only.
05. Vertical Reinforcement are not visible at he crack developed portion.
06. Material Used for Construction might have been not of tested quality. For such type of structure it is a MUST.
07. Regarding Design and Detailing my comments are reserved,. With out seeing the Drg.it may not be fair to guess.
Warm Regards,
T.K.RAMDAS, M.I.E., F.I.V., F.I.I.T. Arb.
On Thu, Jan 23, 2020 at 10:56 PM indutridibesh <forum@sefindia.org (forum@sefindia.org)> wrote:
[quote] Here is a link to the complete videohttps://youtu.be/vUEhqlBTCqo
The circumferential crack in the shaft is clearly visible from some time ahead of collapse. The crack might be due to inadequate reinforcement and/or weak joint in concrete as well.
If the shaft wall is thin enough in proportion to its diameter, then the wall would wobble and it may fail when there is bending of the shaft.
On Thu, 23 Jan, 2020, 14:27 uhvaryani, forum@sefindia.org (forum@sefindia.org))> wrote:
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