Time ripe for increasing use of steel in infrastructure – Mr Sushim Banerjee
Mr Sushim Banerjee DG of INSDAG in his personal capacity wrote for Financial Express thanks to the recent Budget announcements by the government giving infrastructure status to affordable housing programmes, it would ease the financial concerns of the developers and would provide immense opportunities for architects, structural engineers and the steel producers to influence them for favouring steel-concrete-composite construction.
Among other areas of infrastructure building, use of steel in roads, bridges (ROBs/culverts/Rail), urban and rural infrastructure (flyovers, underground tunnels, commercial complexes, stadiums, sports complexes, airports, ports, eco parks, industrial corridors) provides an ideal solution.
Steel scores over other competing materials in terms of safety, durability and aesthetics. Advantage of steel use in Tension offers ductility and steel structures become more resilient to natural calamities such as earthquakes and storms as steel is well suited under seismic zones. The use of prefabricated structures makes a much faster and dust free, noise free construction and does not cause any disturbances to the surrounding areas.
For commercial complexes and high rise buildings, the extra space available with steel frames as compared to concrete slabs offers significant financial gains in terms of rents, lower interest burden due to early completion and higher carpet area.
A classic example of steel’s endurance and ductility (permanent deformation through elongation or twisting at room temperature without fracturing) is the Howrah Bridge at Kolkata.
Built in 1943, this cantilever bridge used around 26,000 tonnes of indigenous steel and still carries nearly 100,000 vehicles, carriages and an estimated 1,50,000 pedestrians every day.
Vidynaasagar Setu, a cable stayed bridge next to Howrah Bridge, Patna Bridge are some of the other large bridges where extensive use of steel has been made.
The Signature Bridge over the river Jamuna is a unique steel suspension bridge that has used steel in the main cables, the suspenders and the Truss Deck.
Indian Railways, through its design and Standards wing known as RDSO, has been building steel bridges across the railway lines all over the country and some of these steel bridges bear testimony to the best advantages of steel use.
Mention may be made of Raja Mundri Bridge over the river Godavari, New Bridge near Naihati (WB), Teesta Bridge at Sikkim, Chenub Bridge at high altitude in J&K. The Bailley Bridges and other small span bridges in the hilly and difficult terrains also provide good opportunities for steel use.
Dismantling of old steel structures to accommodate new designs and elegance would always provide a high salvage value of steel which is 100% recyclable and therefore maintains the inherent properties of original steel.
The reuse of countless products especially rail and automotive components is also made possible.
It has been empirically established by World Steel Association that in terms of environmental sustainability, the changes at every phase in the steel production process over the past 50 years have resulted in significant improvements in the resource and energy efficiency in steel production including a 60% drop in energy consumption per tonne of steel produced.
All these factors counted to calculate Life Cycle Cost puts steel at the top of the list of cost effective materials.
In Indian roads the use of steel is minimum. The need for wire meshing under the road surface that could provide maintenance free, clean surface for heavy loads is not felt in our country and this has also prevented use of Continuously Reinforced Concrete Pavement (CRCP).
The use of crash barriers on both sides of National Highways is guided by the IRC-84 guidelines which are outdated and does not address the real concern of safety points of view.
Even in the hilly areas, there are large tracts on one side without any barrier. It is incumbent on steel industry to approach IRC to issue new guidelines covering these features. Also the use of crash barriers on the medians (dividers) of National Highways is loosely regulated leading to high incidence of fatal accidents.
This is being taken up with IRC to amend rules. One km of roads needs 55 tonnes of steel (galvanised sheets and structurals) for crash barriers on both sides in NH and hence has a good potential of increasing steel consumption.
Nearly 40% of steel goes for manufacturing engineering equipments and machineries. The need for steel intensive excavators, high rise cranes, dumpers and other heavy duty equipments depends on demand from infrastructure and construction sectors.
The demand for pipes and tubes, household appliances and furnitures, electrical equipments, machineries, automobiles, bicycles and a host of other processing industries need steel for making finished products.
This demand depends on rise in disposable household income, government and private consumption expenditures, exports, transport and communication facilities.
Source : Financial Express