Monday, November 14, 2011: 06:01:21 PM

Infrastructure

Steeling Beauty

Ashwani Gupta explains the importance of structural steel in modern-day construction

The construction industry was a different place before modern engineering facilitated the necessary technology to help in the manipulation of concrete and steel. Although concrete has been a dominant favourite in construction, especially in architecture that involves wood, adobe, thatch, and cave dwellings—steel’s strength-toweight quotient has won it the favour of many developers. Steel allows for the economic use of floor area and space, easily accommodating additional structural details to thereby allow modifiable construction schedules. Here, we take a look at the myriad uses of structural steel and the advantages of this raw material in construction.
 


Armour of Steel
In India, steel composite structures are increasingly being recognised as agents of revolutionary building within the industry. Steel’s strength and ductility, combined with solid engineering and design flexibility, have made it a material-ofchoice. A favourite with developers for use in the seismic zones, modern-day architecture has undergone a sea change owing to the use of steel and composite materials, which are being used to build extraordinary super structures and high-rises. Currently, the practice of building with steel in India is in its infancy stage, even though this is more dominant in the industrial and infrastructure areas. In India, steel is used in the construction of a mere one percent of high-rises, whereas in the UK, this figure adds up to a whopping 70 percent.

Given the spurt in construction projects in the country, India has the potential to easily double the use of structural steel over the next decade. The structural steel market in India exceeds seven mn tonnes, and has been growing at an impressive rate of 9–10 percent per annum over the past few years. This market has experienced a noticeable growth surge, as compared to the steel and construction industry GDP. Structural steel is easy to shape because of its ductility, and architects can easily work with this material to form intricate designs and build strong framing systems. With conceptual designs increasingly becoming the norm, innovation coupled with the right technology is helping to turn complex designs to reality. Structural steel sections can be bent and rolled to create non-linear members—an advantage most framing systems do not provide.

The Right Kind of Material
Structural steel offers various advantages over other commonly-used raw materials. It allows optimum utilisation of floor space as steel columns are leaner than columns made of any other materials, resulting in larger floor area. Structural steel calls for a very low foundation cost due to its excellent strengthto- weight ratio.

Steel can also be easily prefabricated as per design requirements to offer greater flexibility and accommodate changes more easily. Steel’s inherent high strength and ductility add more safety to structures. Other benefits of steel include superior malleability and straightness, its economic application and reasonable cost, and the fact that a lot of it is saved due to lower sectional weight and higher strength.

Multicoloured, Multifaceted Manufacture
Multicolor Projects (India) Ltd (MPIL) is a manufacturer of complex steel structures, preengineered buildings and fabricated solar panelmounting structures, and also has a presence in iron ore mining and logistics. The company has a production capacity of 50,000 t structural steel. Steel structures forged by Multicolor Projects have been used in the Mumbai International Airport project, the largest blast furnaces of the JSW Steel Iron Making Zone in Karnataka, the 63-storey Marathon Futurex Tower in Mumbai, and the 100 mW solar farm by Surel Solar in Gujarat
.

About 88 percent of structural steel is made by recycling; further, steel manufacturers are constantly working to reduce the carbon footprint of steel manufacture. There has been over 30 percent decrease in the energy used for steel production in the past three decades. The assembly process of structural steel adds to its sustainability quotient as compared to concrete construction even further, and also results in minimum debris at the time of demolition.



Steel has strong ability to accommodate exceptional loading in the event of an earthquake or explosion. Its sturdiness, and hence lower vulnerability makes it an apt choice for high-rise buildings. Time is a crucial factor in the construction of high-rises, since speedy project completion is especially important for developers. With the use of hot-rolled sections, the fabrication and erection process of steel structures can be accelerated, thus resulting in faster construction as compared to RCC structures.

Leading By Example Here are a few examples of noteworthy applications of steel in projects all over the country.

􀂉 Marathon Futurex is a collective project of commercial high-rises in Mumbai. MPIL is associated with this project for the supply and fabrication of floor beams and structural steel plate sections for composite slabs to ensure speedy and costeffective construction.
􀂉 The Infosys Technologies Ltd office at Hinjewadi, Pune has a unique steel-framed shell with a glass and aluminium cladding in the shape of an ellipsoid.
The shell is divided into 16 radial parts, and the surface of the shell forms a trapezoidal grid. It is made up of 450 t of structural steel, and it is largely on account of the use of steel as the primary raw material that this complicated design was completed in only six months.
􀂉 Sunshine Tower is supposedly the tallest commercial steel building in Mumbai.
􀂉 Trump Tower is an upcoming and much talked-about residential project in Mumbai that will be the first of its kind in the country. It is designed to rise to 67 storeys, with a construction area of 3,00,000 sq. ft.



Noteworthy Structuring
Structural steel framing systems for open-deck parking structures were not a common architectural component in the US. A few years ago, many professional parking lot designers had never even considered using structural steel as a framing system alternative. In fact, only a few areas in the country boasted of structural steel-framed parking structures. However, post-tensioned decks on structural steel frames had been used successfully in the Pittsburgh area for some time now.

Over the past decade, hybrid systems that utilise pre-cast double tees on steel frames have grown in popularity in New York City and New England. However, a notable majority of parking lot architects believe that the US has understood very little of the use of steel-framed systems. Today, structural steel-framed parking structures are being built in all parts of the country. The market share of steel-framed parking structures has quadrupled.

Owners and developers are actively trying their hands at using steel as a framing system and are discovering the multitude of advantages that steel brings to the table—cost savings, accelerated construction schedules, quality, security and sustainable construction. Structural steel is a preferred recyclable resource over other materials and its use is gaining ground as a means to conserve natural resources.

Even though the use of structural steel is rapidly growing in the construction world, it is still a relatively new concept. Numerous factors have contributed to the growth of this market. Of these, one of the most influential was the highly favourable post-earthquake performance of buildings that used structural steel as raw material—specifically four earthquakes in California and Japan (San Francisco, Kanto, Santa Barbara and Long Beach). These results gave engineers greater confidence in steel as a reliable material for earthquake-resistant design, since there were typically fewer problems observed in steel structures as compared to concrete and masonry buildings of similar size and scale.

As architects and builders seek upgraded and innovative methods of building, the structural steel industry is constantly working to meet the varied requirements and specifications. In terms of its suitability as a raw material, edifices featuring structural steel have been proven to have high strength, high performance and a considerably lower weight as against composite structures.

The author is the Founder and Managing Director of Multicolor Projects (India) Ltd.

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