Rebar Detailing to upgrade quality of RCC Structures

1. INFRASTRUCTURE SEPTEMBER 19, 2011 3
Rebar detailing to upgrade
quality of RCC structures
Rebar detailing is a How to reduce 15 per cent. However, when rebar
rebar wastage detailing is applied, placing issues
necessary first step Measures are necessary at site to are visually seen in the drawings and
to convert structural improve rebar tying and placement can be corrected before cutting the
quality. This can be achieved by bars. This can save substantial time
drawing into a and money.
introducing the practice of reinforcing
bar bender bar (in short, rebar) detailing and How to do rebar detailing
understandable preparing placement drawings. Rebar Rebar detailing is best done using
detailing is a necessary first step to specialty software designed for the Responsibility for volunteer to show these records for
drawing, called rebar convert structural drawing into a bar rebar detailing an independent third party inspection.
purpose. Professional rebar detailing
placement drawing bender understandable drawing, software has in-built validations to It is a builder’s responsibility to In that list, the rebar placing drawing
called rebar placement drawing. control rebar size, length, leg values, prepare rebar placing drawings; it is doubtful one. While handing over
This rebar placement drawing gives bend shapes, bending radius, etc so acts as a bridge between design the building, a soft copy of the
a pictorial image for the bar bender that quality of the placing drawings and construction. Construction documentation should be given to
Steel is the most expensive material (iron worker) as specified by the is controlled. practices like pour sequence, ability the buyer. In future, if any repair or
that goes to form reinforced concrete designer. In some software, the wastages to construct column, wall in one or alteration is required on the structure,
(RCC). RCC is the major component A design drawing given by a can be previewed before generating more lifts, market available stock rebar placing drawings would be of
of our infrastructure. Therefore, structural engineer does not show the Bar Bending Schedule (BBS). The lengths, and opportunities for ordering great help.
economy in use of steel and avoiding bar clashes or real congestion of detailing lengths can be modified to special lengths are considered while Advantages of
wastage of steel at construction site rebar. Hence, bar clashes and fitting reduce the wastage. After modifying detailing. rebar detailing
is most important. It is time that our problems are checked automatically. the details, an optimised BBS is Detailing by Since the placing drawings
builders and contractors introduce In the current practice, the laps for generated automatically. are checked against the structural
globally adopted practice of rebar rebar are not planned. This leads
responsible person
It is necessary to have a specific drawings, the BBS generated ones will
detailing to improve the quality of our to wastage. Large numbers of cut provide validated bill of quantities.
rebar detailing manual authenticated
RCC infrastructure and avoid wastage bars are thrown away as scrap. This STEEL Previewing the placing issues
by the Bureau of Indian Standards
of precious steel. wastage can be as high as 10 to enables us to correct costly errors
(BIS). This will have to incorporate the
recommendations of the Handbook even before they occur.
on Reinforcement Detailing, already The structures will be constructed
available as a special publication of as per the structural design.
the BIS. The wastage is correctly assessed
Detailing requires a responsible and reduced.
person who knows CAD drafting and The ISI Code provisions can be
structural drawing reading. He has fully checked on each and every piece
to be taught to use the professional of rebar before construction.
rebar detailing software and should Optimised and accurate BBS is
know the basic practices of rebar automatically generated.
detailing. Introduction of the rebar detailing
In the absence of a specific rebar and placing preparation is the first
detailing manual, unlike in the US, step towards saving steel. Rebar
some professional rebar detailing detailing is unavoidable whether it is
companies, who are already working a small apartment building or a huge
for international markets, could infrastructure project.
publish this, in the best interests of
our country and use it as an industry
standard. Amish
Quality certification Parikh
for structure The author is Center
Director - RGS Institute
Our builders should maintain for Construction
certain documentation in proof of Management and
Managing Partner,
the quality of the structure and Skyspan Technologies
Earnings, not order book to boost India to invest $1trillion in infra
construction firms’ valuations
Prime Minister Manmohan Singh arbitrary decisions. “Infrastructure will transparency are vital touchstones
said recently that good road network play a key role in achieving our growth that should be used for judging our
CRISIL Research, India’s leading companies have a healthy order
across the country is of paramount target of nine per cent. Our effort is to level of success. These are especially
independent and integrated research book of 2.5x FY11 revenues which
importance to achieving nine per double the investment of $500 million important when we deal with the
house, believes that earnings, not order provides good revenue visibility and
cent growth, targeted for the next in the 11th Five Year plan to around $1 private sector. We must remember that
book, will drive the valuations of Indian interest rates are expected to peak in
Five Year Plan (2012-13 to 2016-17), trillion in the 12th plan,” he said. these are public projects where public
construction companies. Though the near term. Additionally, one cannot
and adequate investment would be “It is also necessary to ensure interest must be foremost in our mind,”
most companies have a healthy order ignore the long-term growth potential
directed towards road infrastructure projects are awarded in a fair and he added.
book, valuations have taken a beating for companies in this sector given the
development. transparent manner to avoid suspicion “It seems a very challenging
due to muted earnings growth mainly large-scale infrastructure spending
At the same time, he insisted of favouritism,” he told a conference task, but I am convinced that our
due to execution hurdles, hardening expected over the next five years.
that the awards on private sector on ‘Challenges and opportunities in economy has the resilience to live
interest rates and stretched working According to Prasad Koparkar,
were placed in a fair and transparent public-private partnership in national up to challenges that lie ahead”, he
capital cycle. In the past one year, Head - Industry and Customised
manner so as to dispel any fears or highways’. He further said that for further said.
construction stocks have significantly Research, CRISIL Research, “The
charges that the government was a large road building programme,
underperformed -- negative 55 per current state of infrastructure is
resorting to any form of favouritism or “efficiency, economy, competition and
cent return compared to S&P CNX increasingly becoming a bottleneck
to the ambitious 9 per cent+ GDP
growth target. Hence, spending on
NEWS BRIEFS infrastructure is imminent. We expect
construction investments to grow at a
NIFTY’s negative 8 per cent. Even
CAGR of 13 per cent to Rs 14.8 trillion
over FY12-16.” Private firms may be replaced in DMIC
though some of these concerns may During the strong growth years of
continue to plague the industry in the 2005 to 2008, construction companies The Cabinet is toying with a crucial of interest at a later stage as private the government is planning to create
near term, CRISIL Research believes were valued on their order book position. proposal from the finance ministry financial institutions are also eyeing a $9 billion (Rs 40,500 crore) revolving
that at current valuations, which are Coupled with robust economy growth for a major equity restructuring plan downstream investments in the fund for DMICDC. “Under the proposal
at historical lows, the risk reward ratio and high infrastructure spending, to replace existing private financial project,” he said. which has already been moved to the
appears favourable given the growth most construction companies traded institutions -IDFC and IL&FS - with “LIC and HUDCO are likely to replace Cabinet - the government will put in
potential of the sector. at their all-time high. However, over government owned financial institutions the private financial institutions,” said $4.5 billion and the remaining $4.5
After registering strong earnings the past two years, the order book in the Delhi-Mumbai Industrial Corridor a senior government official. “The exit billion will brought in from Japanese
growth of ~60 per cent during FY05- has witnessed muted growth and Development Corporation Ltd proposal has been made on the basis banks and financial institutions,” he
08, construction companies reported profitability has weakened, resulting in (DMICDC). IL&FS and IDFC together of finance ministry’s recommendations said.
just 2 per cent growth during FY08-11 re-pricing of construction companies. hold 51 per cent in DMICDC. IL&FS to Cabinet.” “Japanese funding institutions
due to weak margins and high interest The construction companies’ holds 41 per cent, while IDFC holds 10 “IDFCs mission is promotion of such as JBIC and the Japanese
costs. While CRISIL Research expects valuations are currently at a historical per cent stake. infrastructure and we had taken the government’s ministry of trade and
earnings pressure to continue to cloud low with median one year forward “The Finance Ministry is keen to stake in DMIC to enable the process,” industry have agreed to finance the
FY12 due to execution hurdles and price-to-earnings ratio (PER) of 6.5x bring in government-owned financial an IDFC spokesman stated. “We remaining $4.5 billion, to be provided
high interest, it believes all is not lost. and one-year forward price/book ratio institutions in DMICDC to replace have not formally heard from the in three phases over three years,”
The silver lining: order awards and (P/BV) of 0.5x. existing private financial institutions,” government or DMIC. However we Kant said.
execution issues have started showing ( A CRISIL report) said Amitabh Kant, CEO, DMICDC. would have no issue to exit DMIC.”
signs of easing up during Q2FY12, “This is being done to avoid a conflict In order to fund the DMIC project,