Dear Mr. Razzak,
Please include following statement
in the forwarding letter you will use while submitting drawings to Consultant:
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Kindly be informed that due to
unavailability of American AISC Standard Hot Rolled WF & C - Sections in
the market, we have proposed substitutes against the same. All substitute
sections proposed are also Hot Rolled Sections but of a different standard,
which are available in nearby countries / regions.
To support our case further we have
attached the following:
Annex 1 - Summary Chart of all
substitutions proposed
Annex 2 - AISC relevant pages
containing data on the cross sections under consideration
Annex 3 - Corresponding data for
substituted members
Annex 4 - Corresponding data for
substituted Channel
You will surely find that in almost
every case we have proposed Rolled Sections which are "higher", i.e.
structural more conservative than the original AISC section given. Only in
the instance of item # 4 of Annex 1, the original AISC beam is
"higher" in size. However, please note the difference is considerably
small and also this section is being used only in two stations out of eleven
total.
Therefore, in light of the above, we
hope to justify our use of these proposed sections and would be tremendously
grateful to your esteemed offices, if your engineers could be kind enough to
accept the same.
Dear Mr. Razzak,
I have read consultant's letter
dated 21st May 2014 and the only relevant points to reply against are in Point
# 1 - Dwgs No. 004 & 008. Please send the attachment in my earlier mail to
the consultant when sending.
Our replies are as follows:
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Drawing No. 004
The Main Girder section as per on
Consultant's drawings, for all but two sites, is the W27 x 84 AISC section.
Now, we have checked this beam and chosen the French Hot Rolled Section HEAA
700 or WPB 700 x 300 x 150 kg/m as a substitute. However, please note this is a
serial designation of the beam. Actual size is as shown in Annex 1.
There, one can easily check that our
proposed size is in fact, "higher", i.e. structural more
conservative than the original AISC section given, whether it is
Moment of Inertia, Gross Cross-Sectional Areas, Flange Compactness, Minor Axis
Inertia, Section Moduli, etc.
To make comparison easier, we have
given a list of the most important structural physical properties of the cross
section. Our chart in Annex 1 shows this comparison for each proposed size
against its original AISC design size.
Drawing No. 008
The Intermediate & End Columns
are both given as W21 x 122 AISC sections. In this case we have chosen the
French Hot Rolled Section HEB 600 or WPB 600 x 300 x 212 kg/m beam as
substitute. Again, as above, the actual size is as shown in Annex 1. Also in
this case, one shall find, our proposed size, despite having flange width less
by 14.3mm, is being structurally more superior in terms of cross-sectional
properties.
Here our request to your esteemed
office is to re-consider the design parameters, in conjunction with assessing
the supporting documents provided herewith, upon which we believe you shall
find our sections suitable.
In general, kindly be informed that
it is only due to unavailability of American AISC Standard Hot Rolled WF &
C - Sections in the market, that we have proposed substitutes against the same.
All substitute sections proposed are also Hot Rolled Sections but of a
different standard, which are available in nearby countries / regions.
To support our case further we have
attached the following:
Annex 1 - Summary Chart of all
substitutions proposed
Annex 2 - AISC relevant pages
containing data on the cross sections under consideration
Annex 3 - Corresponding data for
substituted members
Annex 4 - Corresponding data for
substituted Channel
Therefore, in light of the above, we
hope to justify our use of these proposed sections and would be tremendously
grateful to your esteemed offices, if your engineers could be kind enough to
accept the same.
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