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Failure of overhead water tank,at BANKURA,WEST BENGAL
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Gauri Chandore
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PostPosted: Thu Jan 23, 2020 6:30 pm    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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.

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[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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PostPosted: Thu Jan 23, 2020 7:30 pm    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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
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PostPosted: Fri Jan 24, 2020 4:30 am    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with 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))> wrote:

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hemraj chanchal
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PostPosted: Fri Jan 24, 2020 5:30 am    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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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PostPosted: Fri Jan 24, 2020 5:30 am    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with 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:

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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PostPosted: Fri Jan 24, 2020 7:24 am    Post subject: Re: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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
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PostPosted: Fri Jan 24, 2020 8:30 am    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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
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PostPosted: Fri Jan 24, 2020 12:30 pm    Post subject: How to apply vertical earthquake load Reply with quote

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
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PostPosted: Fri Jan 24, 2020 12:30 pm    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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
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PostPosted: Fri Jan 24, 2020 12:30 pm    Post subject: Failure of overhead water tank,at BANKURA,WEST BENGAL Reply with quote

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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