39-40 ARC May11 ProdSpot Structural Steel

product spotlightStructural Steel

039 039 www.architectandinteriorsindia.com | MAy 2011 | ARCHITECT and INTERIORS INDIA

The futuristic world is always por-

trayed as one high on technology and

invention. Most sci-fi movies represent

this with an excessive use of metal and

metal surface structures. In the global

context, therefore, it’s no surprise that the

use of structural steel for construction is

on the upswing. And India is fast catching

up with this trend.

An alloy, steel has been used extensively

in the construction industry. However,

its application has now gone beyond the

use of basic MS bars. Steel members such

as beams, columns, floor plates, of varied

specifications are becoming more promi-

1

With our cities groWing vertically, the use of

structural steel for construction is continuing to mount, observes carol ferrao

1. With the assitance of technology, the use of strucutral steel is becoming easier and more comprehensible.

Building Information Modeling (BIM)

and 3-D interoperability are some technol-

ogy options that assist architects and steel

specialist contractors in the fabrication

and erection of building structures. This

shop fabrication mode enables work to

continue on site while the steel members

are being manufactured – an option that

concrete does not offer. Kamal Hadker,

MD of Sterling Engineer Design Consul-

tancy Services Pvt Ltd, points out, “RCC

slabs require 28 days of curing to gain

full strength, but with structural steel this

28-day process can be eliminated – thus

saving valuable time and labour.”

upward Mobility

nent. Structural steel is also gaining vast

popularity as a framing material, specially

in the commercial sector in India – for

high-rises in particular.

One of the advantages of structural

steel is its ability to speed up the construc-

tion process. Its design, fabrication and

assembly cycle allows the framing system

to be completed at a much quicker pace.

Dr Rajkumar Singh, director of Kalyani

Centre for Technology and Innovation,

reinstates this: “After making mainframe

ready, which can be done quite fast, paral-

lel construction activities can continue on

all floors – saving 20-30% of time.”

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040 ARCHITECT and INTERIORS INDIA | MAy 2011 | www.architectandinteriorsindia.com

Structural steel has the ability to adapt

to design, a plus point architects and

designers long for in framing systems.

With conceptual designs being the norm,

innovation is turning complex design into

reality. Structural steel sections can be bent

and rolled to create non-linear members,

an advantage most framing systems fail

to provide. Take, for instance, the Infosys

Technologies Ltd office at Hinjewadi, Pune.

Illustrates Dr Singh, “It has a unique steel

framed shell with glass and aluminium

cladding in the shape of an ellipsoid. The

shell is divided into 16 radial parts. The

surface of the shell is formed out of a trap-

ezoidal grid. It has consumed 450 tonnes

of structural steel. Thanks to the use of

structural steel, this interesting structure

was completed in a span of six months.”

About 88% of structural steel is made

from recycled products, and steel manu-

facturers are making constant attempts to

reduce its carbon footprint. According to

experts, there has been over 30% decrease

in the energy used for its production in the

past three decades. The assembly process

adds to its sustainability quotient when

compared to concrete construction, and it

also results in minimum debris at the time

of demolition.

Besides its ‘recycle’ nature, structural

steel can contribute to a sustainable en-

vironment in other ways. When designed

exceptionally well, it can provide a tight

building envelope for less air loss and

better HVAC performance over time.

Because of its shop fabrication, it reduces

waste on site. Steel also has an outstand-

ing reclamation rate, and its magnetic

property facilitates easy separation from

other materials. These attributes play a

major role in achieving LEED credits for

a structure. Another plus point is that no

water is used.

“Statistically speaking, the building

industry provides 5% to 10% of worldwide

employment and generates 5% to 15%

GDP; and the built environment accounts

for 40% of energy consumption, 40% of

carbon emission, 30% of the consumption

of natural resources, 30% of waste genera-

tion and 20% of water consumption.” says

Subodh Shinde, manager, ArcelorMittal

International India. Clearly, this material

could make a big difference in the creation

of a more sustainable environment.

Structural steel is particularly favoured

for high-rise structures. Sunshine Tower,

the tallest commercial steel building in

Mumbai, testifies to its many advantages.

Having a relatively smaller footprint,

structural steel was the only plausible

solution. The service core of the building is

made of RCC and the office space in steel,

resulting in a composite structure. The

steel columns are placed at the periphery

level, thus giving clear floor space without

the column in the span. The steel columns

remain of uniform height throughout the

structure, an advantage only structural

steel could provide.

“Steel having better ability to accom-

modate exceptional loading in the event of

earthquake and explosion, is better suited

to high-rise buildings, since these are more

vulnerable,” maintains Dr Singh. Time is

also a crucial factor in the construction of

high-rises, as Shinde elaborates, “With the

use of hot rolled sections, we can acceler-

ate the fabrication and erection process of

steel structures – which results in a faster

construction process in comparison to

RCC structures.”

Despite its many advantages, there are

many apprehensions among architects and

2&4. Strucutral steel is used in the MMRDA office in BKC, Mumbai.

3. Subodh Shinde, manager, ArcelorMittal International India

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sult in reduced consumption of structural

steel. Profile metal decking that increases

the speed of construction and cold formed

steel trusses and wall panels that facilitate

growth of pre-engineered steel buildings,

are other innovations.

There are many parameters one must

consider while choosing steel as a main

framing system. Hadker states, “The use of

structural steel requires careful planning

in advance and discipline in its fabrication

and assembly on site.” The involvement of

key professionals like structural engineers

and steel contractors from the initial

stage of the project is crucial. A suggested

guide by Shinde: “The quality of steel can

be judged by its appearance. The more

lustrous the surface, the more refined the

steel. To summarise, the quality of steel is

measured by its hardness, brightness and

smoothness of surface, and the absence

of depressions or troughs. In general, the

choice of the steel grade is ruled in various

design codes. Several requirements are

specified: choice according to the material

properties, ductility requirements, tough-

ness and through-thickness properties.”

Discloses Anatharaman: “Steel is a safe

material and the fabrication eco-system

has been available in India for a long

time.” He suggests that composite struc-

tures that use high-strength concrete and

steel will be the most preferred construc-

tion choice in the future. While Hadker

believes that readymade structural designs

and mass production could be the futuris-

tic outlook for the sector.

The lack of information had dissuaded

the Indian building industry from using

this framing system for a long time. But

from the change in trends, it is obvious

that structural steel is making the cut. A&I

of different materials or systems can be

used to protect structural steel – such as

gypsum coating on steel members, mineral

fibres and cementaneous material that are

spray applied directly on the steel mem-

bers. Suspended ceiling systems are also

available for protecting floors and beams,

as well as the composite construction in

which concrete covers the steel members.”

Some experts such as Srinidhi Anathara-

man, founder and CEO of Geodesic Tech-

niques, however, stress the importance of

fire engineering – wherein encasing or fire

protection can be determined effectively

and as per requirement, resulting in better

cost management.

With architects and builders seeking

upgrades and innovative methods, the

structural steel industry is constantly work-

ing to meet the varied requirements and

specifications. With respect to materials,

steel members are now available with high

strength, high performance steel that re-

duces the weight of composite structures.

Fire-resistant steel, corrosion-resistant

steel, cladded/coated steel panels, normal

and coloured stainless steel are some

specific materials that have improved

the functional nature of steel members.

“ArcelorMittal has succeeded in creat-

ing structural steel combining high-yield

strength with excellent toughness at low

temperatures and outstanding weldability.

These material properties were considered

incompatible until now,” adds Shinde.

Steel sections and beams are available in

different shapes to meet specific require-

ments. For instance, the H-beams that re-

designers about structural steel. Firstly,

there is a perception that it’s expensive as

compared to concrete. Most engineers and

related professionals respond to this query

by comparing the lifecycle of the struc-

ture. Structural steel with its properties

provides better durability to the structure.

“The total fabricated and erected cost of

the structure saved due to faster construc-

tion, and more returns by selling more car-

pet area should also get considered in the

cost analysis while making a comparison,”

declares Shinde.

Fire safety issues associated with struc-

tural steel is another anxiety cited by most

professionals and clients. In the case of

common fire, steel can lose its strength at

high temperature. A preventive measure

is the provision of encasing and partial

encasing of steel. Shinde offers some sug-

gestions, “Apart from a water sprinkling

system through the building, a variety

5. Steel sections can be bent and rolled to create non-linear members, making it ideal for conceptual designs.

6. Completed in a period of 27 months, Sunshine Tower is the tallest commercial steel building in Mumbai.

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checkpoints to choose your steel•Consistencyofproduct•Goodstrength,toughnessandweldability•Higherfatiguestrength,especiallyforbridges•Betterfireresistance,earthquakeresistance(highductility) andcorrosionresistance•Betterdimensionalaccuracy•Properidentificationandcertificationofproducts•Finegrainedsteeltobepreferred•Lesssurfacedefectsanddiscontinuitiesneeded

Information:courtesyDrRajkumarSingh,directorofKalyaniCentreforTechnologyandInnovation

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According to you, which is the

most note-worthy structure that

used steel extensively in India

and abroad? What do you find

interesting about it?

Manjunath Raghavelu: In India, we

have few already constructed applications

of structural steel. But we would like to

give an example of the ongoing Trump

Tower, a residential project in Mum-

bai. This will be Trump’s first signature

project in India. Trump skyscrapers are

considered iconic in several parts of the

world, such as the Trump World Tower

overlooking the United Nations’ office in

New York, or the Trump International

Hotel and Tower Dubai. Trump Tower

India will be a 67-storey high-rise building

with a construction area of 3,00,000sqft

and is expected to be as prestigious as all

of Trump’s other American and interna-

tional projects. ArcelorMittal has supplied

Jumbo European sections with high-

strength Histar 460 for composite column

application. The total cost of construction

of this project is estimated at approxi-

mately $360.4 million.

Internationally, we have a number of

applications of structural steel construc-

tion. The Hearst Tower in Manhattan,

New York, USA, is an excellent example of

architecture and design. It is constructed

Manjunath Raghavelu, MD of aRceloRMittal inteRnational anD DR RajkuMaR Singh, DiRectoR of kalyani centRe foR technology anD innovation, DiScuSS Steel StRuctuReS

expert opinion

using 85% recycled steel and is designed to

consume 26% less energy than a building,

which minimally complies with the state

and city energy codes. As a result, it is the

first new occupied office building in the

city to have been given a gold rating, under

the US Green Buildings Council’s Leader-

ship in Energy and Environmental Design

(LEED) programme. Over 85% of the steel

used for the structure is recycled material.

The Histar steel sections made in Differ-

dange (ASTM A913 grade 65, wide flange

structural shapes per ASTM A6) are used in

the wind bracing and gravity load system.

They are visible in the facade as diagonal

lines over all faces of the skyscraper. In

fact, these structural members are inclined

and function as bracing and column at the

same time. This structural system is called

a Diagrid, and is extremely weight efficient

as it contains roughly 20% less steel than a

conventional perimeter frame would - sav-

ing approximately 2,000 tonnes of steel.

Structural steel tonnage is about 10,000

tonnes. External cladding of tower Diagrid

is profiled stainless steel.

Dr Rajkumar Singh: Burj Khalifa,

Dubai is definitely a noteworthy steel

structure built in the last decade. The spire

of Burj Khalifa consists of 4,000 tonnes of

structural steel besides 55,000 tonnes of

reinforcement bars. The exterior cladding

of Burj Khalifa consists of 1,42,000MT

of reflective glazing and aluminium and

textured stainless steel spandered panels

with vertical tubular fins. This keeps the

building cooler. Taipei 101 is another

outstanding landmark structure.

What are the advantages of using

structural steel in high-rises in

particular?

Raghavelu: In the last few decades, ma-

jor developments in architectural look and

an increasing demand for lighter and high-

rise buildings resulted in an organised evo-

lution of structural systems. Steel structures

were predominant in these developments

and profiting from the inherent properties

of this material. The developments in the

steel industry contributed to the structural

efficiency of these new framing concepts

by providing new heavy sections and high-

strength steels with outstanding mechanical

properties. We can avoid the heavy RCC

column sizes and reduce the weight of the

structure extensively using structural steel,

which results in increase in carpet area.

Construction time is an important factor

in high-rise construction, and by using hot

rolled sections we can accelerate the fabri-

cation and erection process – which results

in faster construction in comparison to an

RCC structure.

Dr Singh: Structural steel has many

advantages in construction. It can be used

as structural members directly or as steel-

concrete composites. Its main advantages

in high-rise buildings are as follows: Faster

construction, floor space saving, saving

in height. Steel having a better ability to

accommodate exceptional loading in the

event of earthquake and explosion, is

suited to high-rise buildings since these

are more vulnerable

What are the upcoming structural

steel solutions that could interest

the design community?

Raghavelu: ArcelorMittal has started

offering high-strength structural steel in

India. This high-strength steel grade is

available in two options: Histar S355 with

yield strength of 355 Mpa and Histar S460

with yield strength of 460 Mpa. Designers

can achieve the economical design by us-

ing this high-strength steel, which results

in minimising steel tonnage requirement.

Section range of ArcelorMittal includes the

sections with a depth up to 1100 mm and

flange thickness up to 140 mm (hot rolled

sections, not fabricated). Use of these


045 045 www.architectandinteriorsindia.com | MAy 2011 | ARCHITECT and INTERIORS INDIA

jumbo sections can minimise the fabrication and transportation cost, which again

results in economical structural steel solution.

Dr Singh: Structural steel enhances construction productivity because of its

shop fabrication approach, which runs parallel. The composite decking using pro-

filed steel decks results in a lot of time saving in building erection, and the steel

cladding panes with inbuilt photovoltaic cells is capable of generating substantial

solar power – thus making steel buildings less power-dependent. New systems

such as Girder-slab, Conxtech and side plate have recently entered the market in

response to designer demand.

What are the fire safety issues associated with structural steel, and

what are the best preventive measures for the same?

Raghavelu: Steel is an incombustible material. However, its strength reduces

tremendously at high temperature due to common fire. A structure subjected

to fire must be safe for the time necessary for the escape of the people and for

the safe operation of the rescue and fire brigade. The performance of these are

directly determined during standard fire tests. In addition to the insulation

characteristics evaluated in the tests, the physical integrity of fire-protection

materials is extremely important and should be preserved during installation.

Required fire-protection assemblies should be carefully inspected during and

after construction to ensure that they are installed according to the manufactur-

ers’ recommendations and the appropriate fire-resistant designs.

Dr Singh: Although steel is vulnerable to fire and loses strength at high tem-

peratures, in most of the cases it can recover properties on cooling, which is not

the case in concrete, wood, etc. Steel structures need a protective skin to keep the

temperature below critical point. Protective boards (like gypsum boards), sprays

(vermiculite cement, Pearlite) or intumescent paint coating are some solutions

available for passive fire protection. Fire-resistant steel is another answer, as its

elevated temperature strength is much higher.

Is structural steel a sustainable option for building construction?

Raghavelu: The objectives of sustainable development are to minimise the

ecological damage resulting from infrastructure creation, operation and main-

tenance. To date, sustainable building design has focused largely on building

in-service energy efficiency. As society makes determined moves towards sustain-

ability, construction has a very important role to play within this agenda, not only

because of its economic and social contribution, but also its impact on the quality

of our lives.

The future global challenge for the construction industry is clearly to meet the

world’s growing needs while at the same time limiting the impact of its burden

by drastic improvement of its activities. In construction, steel has developed as

a material of choice and offers a wide range of solutions that can make building

more energy efficient, less costly to operate and more comfortable. We at Arce-

lorMittal believe strongly in steel’s values for Green building and are committed

to helping deliver the benefits that our solutions bring to our customers, their

buildings and their owners. Steel is 100% and indefinitely recycled without any

loss of quality.

Dr Singh: Structural steel is the most recycled material on our planet. In fact,

today’s structural steel is made of 88% recycled product. The carbon footprint of

structural steel has been reduced by 47% since 1990. Energy used in the produc-

tion of structural steel has been reduced by 9% in the past 10 years and over 30%

in the past three decades.

No water is used in steel building erection. On demolition, a steel structure

does not create debris, and the entire material is reused/recycled.A&I

STeeLHavInGBeTTeRaBILITyToaCCommoDaTeexCePTIonaLLoaDInG...ISBeTTeRSuITeDToHIGH-RISeBuILDInGS–Dr rajkumar singh

39-40 ARC May11 ProdSpot Structural Steel

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Transcript of 39-40 ARC May11 ProdSpot Structural Steel