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Crane load

 
This forum is locked: you cannot post, reply to, or edit topics.This topic is locked: you cannot edit posts or make replies.    www.sefindia.org Forum Index -> E-Conference 23rd Sept 2003
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ALOSNL
SEFI Member
SEFI Member


Joined: 26 Jan 2003
Posts: 2

PostPosted: Tue Oct 14, 2003 10:56 am    Post subject: Crane load Reply with quote

Dear Sir

In continuation with the view points of Mr. Jignesh Shah I would like
to point out that neither in the earlier IS:800 nor in the newly drafted
IS:800 has any provision of relative displacement of the top of rail
while the crane is in operation.

In industry buildings with high crane capacity relative displacement of
the top of rail becomes a critical aspect from serviceability point of
view.

A definite recommendation in this regard in given by the Russian Code
of practice is reproduced below with heavy service conditions. Refer
Clause No. 10.7 & Table46 of SNiP II - B.3-72

1> H/2500 (with plane structural scheme)
2> H/4000 (with 3D structural scheme)

where , H = Height of column from u/s of column to the top of crane
rail

It has been observed the above clauses make the frame very heavy and
thereby uneconomic. So the plant owners for smooth serviceability of
crane and to reduce vibration have restricted the relative displacement
to 10mm to 15mm.

So Iwould request the Committee members of IS:800 to introduce a clause
which will be a guideline for the relative displacement of the top of
the rail.

Regards



ALOKES GUHA
L&T - SARGENT & LUNDY LTD.- BARODA
E-Mail : alosnl@ltecd.ltindia.com
Phone : 02652772390 (Ext 5504)



Quote:
Quote:
Quote:
JMSSNL@ltecd.ltindia.com 10/14/03 03:25PM >>>
*************************************************
SEFI e-Conference on draft revision of  IS:800, October 06 to 18, 2003
*************************************************

Dear Sir,

Present Steel design code IS:800:1984 is having guidelines for crane
load combinations (Article 3.4.2.4).  Requirement of this provision
was
necessary in year 1984 since at that time prevailing loading standard
IS:875:1964 did not have similar provisions. In subsequent revision
IS:875  part 2 -1987 cl.6.4 introduced similar provisions with little
more elaboration.

Hence, IS:800 provisions have become superfluous and shall be removed
from subsequent revisions. To my surprise I find that IS:800 draft
code
has retained original provisions.

A close look at both brings out small difference between two

Footnote below article 6.4.3.2 of IS:875 states "Lateral surge force
.....However, if there is only one crane in the bay, the lateral and
longitudinal forces may act together simultaneously with vertical
loads"

On the other hand in  Draft version of IS:800 article 3.5.4  talks
about lateral and longitudinal loads not to act simultaneously and has
no such rider for one crane in the bay situation.

In my opinion , crane load combination shall be left for IS:875 to
decide and shall be removed from IS:800 which essential is for steel
structure design. Also any future revision in IS:875 may create
further
anomalies between two provisions.

I would appreciate learned SEFI forum members to provide their views.

Thanks,


Jignesh



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