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Posted: Sun Sep 18, 2011 4:01 pm Post subject: Sikkim Earthquake Sept 18 2011
Dear All
You must have by now heard of the 6.8 Magnitude earthquake with epicentre in Sikkim 68 km NW of Gangtok.
We pray and hope that there is min damage and loss of lives. We request all SEFI members in Northeast, W Bengal, North India to share their experiences of the earthquake- both personal as well as observations of any damage etc.
We hope in this way SEFI can become a repository of personal earthquake experiences of structural engineers. We will create a special page for this after collating all information.
Thanks much in advance,
best regards and keep safe.
Posted: Sun Sep 18, 2011 6:42 pm Post subject: Sikkim Earthquake Sept 18 2001
Dear Alpa,
Yes, as you have pointed out it is difficult time for people of Sikkim, rains, landslides are certainly going to hamper the rescue work..!!
Arvind Jaiswal
On Sun, Sep 18, 2011 at 9:58 PM, alpa_sheth <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
Dear All
You must have by now heard of the 6.8 Magnitude earthquake with epicentre in Sikkim 68 km NW of Gangtok.
We pray and hope that there is min damage and loss of lives. We request all SEFI members in Northeast, W Bengal, North India to share their experiences of the earthquake- both personal as well as observations of any damage etc.
We hope in this way SEFI can become a repository of personal earthquake experiences of structural engineers. We will create a special page for this after collating all information.
Thanks much in advance,
best regards and keep safe.
Posted: Sun Sep 18, 2011 11:44 pm Post subject: Sikkim Earthquake Sept 18 2001
1. We express our sympathies with all those who are affected in someway or other - loss of life/injuries/loss of property
2. Theoretically the event is no surprise - since the first version of IS:1893, the region is identified as in the severest seismic zone.
3. This is definitely not the maximum potential event for that region - could be called as an event that would occur during the life time of structure
4. From an engineering point of view, this event could be known for changes that must come for APPENDAGES - Towers for Mobile Communications located on Roof of existing Structures. [the Bhuj event, brought our attention to STILT Buildings
COMMUNICATION TOWERS LOCATED AS APPENDAGES
The first reports on TV indicated wide spread disruption of mobile communications due probably to failure of Towers.
The operators found it cheaper - no need to acquire land and the owners were happy to get easy funds and we see that most such towers are located on top of existing buildings [which buildings were not originally designed to support such appendages]
(A) The failure in this Sikkim event could be due of failure of structure or the towers causing failure to the structure
This could be found out by field survey - behaviour of nearly identical structures - some not having the tower appendage
[We have a most notable experience - among the various monoliths of non-overflow sections of Koyna Dam, only M-17 which had a tall observation tower as an appendage suffered damage]
(B) I presume that the design of such appendage on the strength of the structure must be cursory -
I wish and strongly urge an immediate research program by IIT-Guwahati on proper modelling of Towers on the roof of different type of buildings
that exist in Brahmaputra Plains of Guwahati and the hills of Shillong
The adhoc and arbitrary clauses of IS:1893 for Appendages are not valid
(C) The authorities should insist on free standing Mobile Communication Towers for important locations of administration.
Mobile communication is not a luxury - it is used by Aam Admi
On a lighter note, BSNL should be happy that their land lines mostly functioned
ARC
On Sun, Sep 18, 2011 at 9:58 PM, alpa_sheth <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
Dear All
You must have by now heard of the 6.8 Magnitude earthquake with epicentre in Sikkim 68 km NW of Gangtok.
We pray and hope that there is min damage and loss of lives. We request all SEFI members in Northeast, W Bengal, North India to share their experiences of the earthquake- both personal as well as observations of any damage etc.
We hope in this way SEFI can become a repository of personal earthquake experiences of structural engineers. We will create a special page for this after collating all information.
Thanks much in advance,
best regards and keep safe.
Posted: Mon Sep 19, 2011 1:28 am Post subject: Sikkim Earthquake Sept 18 2001
Dear AllProf Arc has rightly pointed out one of the probable causes for the disaster in Sikkim. It is seen that most of the mobile towers are allowed to function in our country with out any analysis of stresses coming over the existing structures. Of course to make their side safer ,they collect a stability certificate from a structural engr. I am told. I am afraid how many of our community take the pain to work out the stresses coming over the structure due the appendages. We take lessons when disasters occur. "Prevention is better than cure" shall be our key word I feel.Prof.Dr. K.A.A.Baker, Kochi
Sent from my BlackBerry® smartphoneFrom: "prof.arc" <forum@sefindia.org>
Date: Mon, 19 Sep 2011 05:33:26 +0530
To: <general@sefindia.org>
ReplyTo: general@sefindia.org Subject: [SEFI] Re: Sikkim Earthquake Sept 18 2001
1. We express our sympathies with all those who are affected in someway or other - loss of life/injuries/loss of property 2. Theoretically the event is no surprise - since the first version of IS:1893, the region is identified as in the severest seismic zone. 3. This is definitely not the maximum potential event for that region - could be called as an event that would occur during the life time of structure 4. From an engineering point of view, this event could be known for changes that must come for APPENDAGES - Towers for Mobile Communications  located on Roof of existing Structures. [the Bhuj event, brought our attention to STILT Buildings COMMUNICATION TOWERS LOCATED AS APPENDAGES The first reports on TV indicated wide spread disruption of mobile communications due probably to failure of Towers. The operators found it cheaper - no need to acquire land and the owners were happy to get easy funds and we see that most such towers are located on top of existing buildings [which buildings were not originally designed to support such appendages] (A) The failure in this Sikkim event could be due of failure of structure or the towers causing failure to the structure This could be found out by field survey - behaviour of nearly identical structures - some not having the tower appendage [We have a most notable experience - among the various monoliths of non-overflow sections of Koyna Dam, only M-17 which had a tall observation tower as an appendage suffered damage]  (B) I presume that the design of such appendage on the strength of the structure must be cursory - I wish and strongly urge an immediate research program by IIT-Guwahati on proper modelling of Towers on the roof of different type of buildings that exist in Brahmaputra Plains of Guwahati and the hills of Shillong The adhoc and arbitrary clauses of IS:1893 for Appendages are not valid (C) The authorities should insist on free standing Mobile Communication Towers for important locations of administration. Mobile communication is not a luxury - it is used by Aam Admi On a lighter note, BSNL should be happy that their land lines mostly functioned ARC On Sun, Sep 18, 2011 at 9:58 PM, alpa_sheth wrote: --auto removed--
Posted: Mon Sep 19, 2011 3:41 am Post subject: Sikkim Earthquake Sept 18 2001
Thanks Alpa for the quick reaction. Looking forward to our special page. ASC India will work out an Intensity map for the event and for this there is a need for as many 'Felt' reports as possible. So can our colleagues who felt this earthquake (or their friends did) wherever they are in India, Nepal or Bhutan, could you please fill the Felt report form at the asc websiteat the links given below?. Such reportss are vital to understanding earthquakes in the subcontinent. Please request friends to fill this in even if they have filled out the USGS felt report form, the data from which is NOT available to us in the subcontinent for research although it is from here.
It is very VERY important
On Sun, Sep 18, 2011 at 9:58 PM, alpa_sheth <forum@sefindia.org (forum@sefindia.org)> wrote:
Quote:
Dear All
You must have by now heard of the 6.8 Magnitude earthquake with epicentre in Sikkim 68 km NW of Gangtok.
We pray and hope that there is min damage and loss of lives. We request all SEFI members in Northeast, W Bengal, North India to share their experiences of the earthquake- both personal as well as observations of any damage etc.
We hope in this way SEFI can become a repository of personal earthquake experiences of structural engineers. We will create a special page for this after collating all information.
Thanks much in advance,
best regards and keep safe.
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