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Tensile and Versatile

Features

Steel is known for its stiffness, high durability capacity and toughness which makes it a go to and safe construction material for builders.

BY BINDU GOPAL RAO

Developers generally prefer steel over cast iron as the characteristics of steel allow them to build taller buildings which are not only more fire resistant but also structurally more sound. Additionally, steel as a product is highly durable and also price reliable thus making it more viable for the developers. The versatility of the material helps in faster construction and it can also be reused by developers since it is a recyclable material.
There are three main types of steel construction – conventional steel fabrication, bolted steel structure construction and light gauge steel structure construction. “Steel is a highly durable metal. It can withstand a considerable amount of external pressure. Hence, steel structures are earthquake resistant whereas concrete structures are brittle. Concrete is not as resistant as steel. It is only because of this advantage that we were able to design structures such as the Sardar Vallabhai Patel Indoor stadium with column free spans of over 50m, and the Wankhede Stadium designed without a single column obstructing the vision of the spectators,” says Amol Prabhu, partner, Shashi Prabhu & Associates.
In addition, steel buildings are lighter than the RCC structures and hence, could possibly reduce the foundation cost and column sizes in certain cases, adds Prabhu.
The quantum of steel re-bars used in a building is dependent on many factors like shape and height of the building, the seismic zone its location is in, wind resistance etc. “It may vary from approx. 3kgs/sq-ft of construction area for a simple 3 storied building to even 10kgs/sq-ft or more, for a super-tall and slender high-rise building. Structural design of buildings in India is guided by various BIS codes which are revised from time to time considering advances in knowledge and learnings from past experiences. It is now very common to see high-rise buildings in most urban and semi-urban locations and the use of steel rebars in construction has gone up exponentially in recent years,” says a Kalpataru spokesperson.

Steel buildings are better resistant to wind and earthquake and popular for ultra-high-rise buildings.
Amol Prabhu

Advantage Steel
Until the past decade, developers preferred using wood over steel for residential properties. Steel structures are light in comparison to other concrete structures and are easy to transport and erect. “With the amount of material used during construction, it is important to use a material which can be produced in bulk and can be built faster by a pre-engineered process to a specific design inside the manufacturing plant. Steel enables this function with greater flexibility, higher strength and stiffness. It is also known to withstand high wind, snow load and seismic load. Moreover, steel being a ductile material ensures no sudden failures,” says Ashish Puravankara, MD, Puravankara Limited.

The quantum of steel re-bars used in a building is dependent on many factors like shape and height of the building.

“Construction as a business has a lot of equity involved in traits such as trust factor, quality and stability of builder among others. To provide the best to their customers, material usage is of utmost importance. Irrespective of how large the structure is steel is one material which just cannot go wrong. Apart from its modifiable and low cost factor, steel is also very innovative and gels with new age construction,” says Hardik Agarwal, CEO & director, Radha Madhav Developers.
Design plays an important role. Steel ceiling joist with proper truss, frames and 3D space frames can span a greater distance than regular wooden joists which help in further enhancing the design of a space. “They also help eliminate interruption of any kind in the column inside the structure which results in more clear space. Steel joists are also stronger in comparison with wood in terms of the material. They do not warp, twist, bow, split or have knots which make it conducive for construction. Due to the durability of steel joists they display long terms benefits since they do not rot, mould or form mildew and are impermeable to termites, vermin and insects thus making them low maintenance,” avers Puravankara.
Sanchit Gaurav, partner interiors/renovation/construction, Housejoy, adds, “As steel joists span greater distance than wooden joists, it opens up the opportunities to try many designs that were not possible before the use of steel. For instance, architects can create column-free spaces which give you large open spaces.”

The weight of steel doesn’t take into account the reduced costs of fire protection and cladding.
Natasha Singh

Use of steel in construction is no longer limited to reinforcement for concrete.

New vistas
Use of steel in construction is no longer limited to reinforcement for concrete. The steel industry is constantly adopting new technologies to develop products and applications that challenge what was previously thought impossible. “Steel construction is evolving from box like steel structures to aesthetically pleasing designs. Acceptance of pre-engineered metal buildings is moving beyond industrial and infrastructure projects and expanding to residential and commercial applications as well. In fact, while steel members are greatly recyclable, the manufacturing of steel is a resource intense exercise,” adds Prabhu. The creation of new and exciting buildings brings architectural demands which are constantly stretching the performance of the structural elements and the ingenuity of engineers. Whether the requirement is for an open structure, a curved façade or a long span, steel meets the challenge with spectacular results. “Construction methods and details have been developed to ensure that steel is able to economically meet the strict acoustic and thermal regulations contained within the recently amended Building Regulations. However, many factors contribute to cost effectiveness and whilst the weight of steel can give a crude measurement of efficiency, it doesn’t take into account the reduced costs of fire protection and cladding and the ease of service installation, which can provide substantial benefits,” says Natasha Singh JMD MESCO Steel.

The Indian steel industry continues to grapple with uncertainties pertaining to the availability.
Rajagopalan

Overcoming Obstacles
Construction of steel buildings does require a greater amount of skilled workforce than the conventional construction.
Rajagopalan, VP, projects, Adarsh Developers, avers, “The Indian steel industry continues to grapple with uncertainties pertaining to the availability and consistent supplies of raw materials i.e. both coal and iron ore still remain a challenge, with the recent closure of mines in Goa adding to the woes of the industry. Even though the marked shift from an allocation process to an auction process of getting mining blocks has brought about considerable transparency; issues pertaining to logistics from the mining areas need to be sorted out to mitigate lag in the evacuation of iron ore, coal and other minerals.”

Construction of steel buildings does require a greater amount of skilled workforce than the conventional construction.

Designers need to be educated on the key aspects of fire proofing of steel structures since steel members typically fail at much lesser temperature than the RCC members. Therefore, designers need to understand the fundamentals of fire safety and fire proofing to ensure safe evacuation of people from the steel buildings in case of fire. Steel in today’s time is used abundantly thanks to its scrap value, longevity and sustainability. “But some drawbacks of steel are its ill-resistance to calamity, possibility of fractures and inability to be molded into any other form. Steel is also susceptible to corrosion in outdoor atmospheres. As much as steel is a construction favorite, these are some traits which is seen to be a setback for steel,” opines Agarwal. The Indian construction industry has witnessed a growth trajectory quite comparable to the development of the overall economic infrastructure of the country. The Indian PEB market is experiencing robust growth fuelled by infrastructure development and the increasing popularity of PEB systems in the industrial sector. Sectors such as automotive, power, logistics, pharmaceuticals, FMCG, and capital goods provide

Steel can be produced in bulk and helps build faster by a pre-engineered process.
Ashish Puravankara

huge growth opportunity for PEB in India. “The greatest challenge for prefabricated and pre-engineered buildings in India is the perception shift from conventional construction to pre-engineered steel structure. Though it’s changing over the years but the pace is still slow and people are still not experimenting that readily. People still tend to look at the conventional methods of construction as the cheaper and the best method, overlooking the long-term benefits,” adds Singh.
Despite these challenges, the usage of steel in the real estate sector has been increasing with every passing year.

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CW February 2019
01 Feb 2019