Preparation of Bar Bending Schedule
Bar
bending schedule (or schedule of bars) is a list of reinforcement bars,
vice-versa, a given RCC work item, and is presented in a tabular form for easy
visual reference. This table summarizes all the needed particulars of bars –
diameter, shape of bending, length of each bent and straight portions, angles
of bending, total length of each bar, and number of each type of bar. This
information is a great help in preparing an estimate of quantities.
The only
difference between the ordinary drawing and the detailed drawing with bar
bending schedule is that in the latter case all the bars will be tagged with
bar mark as per the legends.
For example: In the former case we only
provide 2-#16 which gives only the details of the number and diameter of the
bar. In the latter case, 2-#16-312 represents all the details including the bar
mark (312).
BAR BENDING SCHEDULE
Length of the bars is measured from the
drawing and can be entered in a schedule. Thus the number of the bars as per
length given in the schedule can be counted and sorted from the drawing. At a
glance, the challenge that has been put forward is that detailers need to show
the minute details of the drawing as explained below. For example: Bend length
at the end of the reinforcement bar (beam) has to be calculated based on how
much development length is available in the column itself. If the width of the
column is high in the direction of the beam, the beam bar length may not be
required to be bend at all. Let us go through the advantages with bar bending
schedules.
ADVANTAGES
WITH BAR BENDING SCHEDULES (BBS) :-
1. Scheduling and proper
bending is strongly recommended for Fe 500. Fe 500 saves 10% compared to Fe 415
steel used presently.
2. Cutting and bending in a
cut and bend factory avoids the wastage completely (2-3%). With BBS, bars can
be cut with planning to reduce the wastage in a site with even the present
setup.
3. There is a general
tendency to group slabs and beams in the usual design methods. In BBS, it is a
must to detail every member separately to account finer geometry and different
forces coming on the structure in the modern design methods. Instead of
grouping members as all members are detailed separately gives reduction in
steel as every member is individually reinforced to resist what it has to.
Finer detailing saves about 5 to 15% steel.
4. Better quality control at
site.
5. Better estimation of steel.
6. Real time estimation
data, with the design.
7. Better control on stock
of steel actually required.
8. Theft and pilferage of steel can be
reduced.
9. Economical order quantity
for better project management.
10. Bench marking quantity
and quality requirements.
11. Optimize your design
based on the quantity of steel.
12. Steel bending and
cutting can commence even before the form work is done.
13. Steel bending can be
done at a separate site, marked and then can be assembled at site, if there is
space limitations.
14. Project time can be
reduced as the bars can be cut and bend before form work is done.
15. What you see in the
drawing is what you get at the site.
16. With a quality data set,
other management software’s (ERP systems) can work on it.
17. A paper less office
concept in the construction industry and associated advantages.
18. Total length of bars
calculated using Engineering formula, leaves nothing to approximation.
19. Mechanization of bending and cutting is
possible. (Cut and bend systems) Reduces labour and time but increases the
reliability.
20. As
the works gets organized, smaller contractors can work on the project at lesser
rate. COST ANALYSIS Consider 1 lakh per ft² building with 15 stories, with 5kg/ft²
steel usage
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