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Seismic Analysis of Liquid Storage Tanks

 
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vmscons
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 16

PostPosted: Thu Aug 19, 2004 11:56 am    Post subject: Seismic Analysis of Liquid Storage Tanks Reply with quote

----- Original Message -----
Message From  Codes
To: rushikesh
Cc: Omprakash Jaiswal ; nimisha@iitk.ac.in ; anilag@iitk.ac.in
Sent: Monday, July 19, 2004 10:59 AM
Subject: RE: Seismic Analysis of Liquid Storage Tanks


Dear Rushikesh:

Thanks for your careful review of the document. I am forwarding it to Dr. Jaiswal. He will make the corrections and also respond to some of the questions that you raise.

Best regards,

SKJ
-----Original Message-----
Message From  rushikesh [mailto:vmscons@eth.net]
Sent: Thursday, July 15, 2004 2:07 PM
To: codes@iitk.ac.in
Subject: Seismic Analysis of Liquid Storage Tanks


Dr. Sudhir K. Jain,
IIT Kanpur,
Kanpur.

Dear Sir,

As specified in Clause 4.2.3, for tank shapes other than circular and rectangular, value of h/D shall
correspond to that of equivalent circular tank..., we can model intze tank which do not have inside
access shaft.

Most of the intze / conical containers supported on shaft type stagings do have inside access shaft.
Due to access shaft inside the tank, convective mode period will not be the same as that estimated
for a tank with equivalent diameter...

Would you throw more light on this issue ?
Did the work carried out by Joshi (referred to in Cl - 4.2.3 of proposed draft) included such tanks ?

I think , spring mass model parameters for such tanks need to be studied based on ratio of diameter of
access shaft to that of diameter of container at top ring beam level.

Also, can we use h / L instead of
h / D (for an equivalent circular tank) for such cases where L can be the inside distance between access
shaft and top ring beam ?


Regards,

Rushikesh Trivedi
rushikesh@vmsconsultants.com

VMS Engineering & Design Services (P) Ltd.
Chitrakoot,
B/H The Times of India,
Off. Ashram Road, Ahmedabad.
Ph:079 -  26588829

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vmscons
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 16

PostPosted: Thu Aug 19, 2004 11:56 am    Post subject: Seismic Analysis of Liquid Storage Tanks Reply with quote

----- Original Message -----
Message From  Omprakash Jaiswal
To: rushikesh@vmsconsultants.com
Cc: codes@iitk.ac.in
Sent: Monday, July 19, 2004 12:42 PM
Subject: RE: Seismic Analysis of Liquid Storage Tanks


Dear Rushikesh,
Thanks!. I have noted the errors in printing and will be corrected in the final copy of draft proposals.

Regarding the convective mode for a container with inside shaft:
For such a container basically liquid gets divided into three parts. Central part has lesser value of L (or D) and two side portions have larger value of L or D.  The central shaft obstructs the convective motion of liquid. Hence convective ma ss of liquid will be less than one obtained by formulae given in code. As a furst cut approach, I will suggest following approach for such a tank:
Equivalent cylindircal tank will have volume equal to volume of liquid only.
The diameter of equivalent cylinder shall be equal to diameter of original tank minus diameter of shaft. With this, for equivalent cylinder one will get higher value of h/D. This will reduce mc and will also reduce Tc, which seems to be logical.
In Joshi's paper, internal shaft has not been considered. I think a more detailed investigation on fluid-structure interaction for such a tank will be needed.

Please let me know if you have any queries on this.

Thanks and regards,

Jaiswal

k.ac.in> wrote:
Dear Rushikesh:

Thanks for your careful review of the document. I am forwarding it to Dr. Jaiswal. He will make the corrections and also respond to some of the questions that you raise.

Best regards,

SKJ
-----Original Message-----
Message From  rushikesh [mailto:vmscons@eth.net]
Sent: Thursday, July 15, 2004 2:07 PM
To: codes@iitk.ac.in
Subject: S eismic Analysis of Liquid Storage Tanks


Dr. Sudhir K. Jain,
IIT Kanpur,
Kanpur.

Dear Sir,

As specified in Clause 4.2.3, for tank shapes other than circular and rectangular, value of h/D shall
correspond to that of equivalent circular tank..., we can model intze tank which do not have inside
access shaft.

Most of the intze / conical containers supported on shaft type stagings do have inside access shaft.
Due to access shaft inside the tank, convective mode period will not be the same as that estimated
for a tank with equivalent diameter...

Would you throw more light on this issue ?
Did the work carried out by Joshi (referred to in Cl - 4.2.3 of proposed draft) included such tanks ?

I think , spring mass model parameters for such tanks need to be studied based on ratio of diameter of
access shaft to that of diameter of container at top ring beam level.

Also, can we use h / L instead of
h / D (for an equivalent circular tank) for such cases where L can be the inside distance between access
shaft and top ring beam ?


Regards,

Rushikesh Trivedi
rushikesh@vmsconsultants.com

VMS Engineering & Design Services (P) Ltd.
Chitrakoot,
B/H The Times of India,
Off. Ashram Road, Ahmedabad.
Ph:079 -  26588829

Yahoo! India Careers: Over 65,000 jobs online.

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