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Construction : Feature | April 2016 | Source : Infrastructure Today

The need for speed

For its swiftness in construction and reduction in costs, PEB structures are increasingly finding new takers from both high-rises and the rural segments alike.
India is the third largest pre-engineered building (PEB) market in the world after the US and China. With a market size of about half a million metric tonne and a growth rate of 8-10 per cent, according to industry estimates, however, the growth hasn't been a pervasive one. For Alakesh Roy, Managing Director, Zamil Steel, India, the PEB market in the past year has been pretty flat. Nonetheless, he says the government's Make in India initiative has helped to create an upbeat mood. 'It can speed up construction in infrastructure projects,' he asserts.

To be sure, the country is setting records in the PEB arena. Sample this: a 33-storey tower built in 99 days; a two-storey facility in 75 days and a 60-m-long metro bridge in less than a week. It's the kind of scorching pace that has won many converts. With the boom in construction, the requirement is for light structures that are quick to erect. Says SS Bhasin, Managing Director, Bhasin Group, who is building a 33-storey tower in 99 days, 'We knew that a PEB steel structure would be easy to get and install. By reducing time-lines, we plan to save about two years of delay in delivering the project.' Another market player, Everest Industries, is currently constructing HCL IT City that entails developing two buildings measuring over 200,000 sq ft in less than six months. Here, much of the work is done using over 3,000 mt of steel beams and columns.

As many more such projects abound, many in this domain are convinced that PEB offers a lot of advantages. 'PEB is fast to fabricate, transport and erect on site in any configuration, including large span, multi-levels, light and heavy loads as well as shapes of roof, as per the design,' says architect CN Raghavendran, Managing Director, CR Narayana Rao (Consultants).

What's in store?
D Raju, Managing Director, Kirby Building Systems India,
says, warehousing is among the sectors fast adopting PEB. 'In warehousing, over 100 million sq ft of space is being added every year,' he informs. The rural thrust of the current Budget is also expected to drive demand for quality roofing from the rural segment and many players are expecting healthy growth. 'The PEB market should grow at 10-12 per cent this fiscal too,' says Manish Garg, President & Chief Executive-Steel Building Business, Everest Industries.

Spurring urban demand as well are areas of growth in segments such as commercial, housing, infrastructure, industrial buildings, stadiums and metro projects, among others. Raju says, 'High-rises are expected to create strong demand in the next five years.'

Meanwhile, the demand is also spreading to smaller cities. 'In tier II and tier-III cities, too, we see some traction,' adds Gautam Suri, CTO and Founder, Interarch Building Products. 'Corporate entities have been increasingly opting for PEB structures in the recent past,' he says.

Time savers
Compared to traditional methods, PEB scores the maximum with respect to speed of construction. Suri enumerates PEB's many advantages, 'Early occupancy and return on investment, mainly owing to reduced construction time of 30-40 per cent; possibilities of large, clear span structures up to 100 m and height of up to 30 m are possible; mezzanine floors can be constructed, which help in maximum usage of space and, hence, provide better utilisation of money spent per square foot.' Steel structures also offer a cost advantage over conventional construction methods. 'Falling steel prices are a positive sign for companies like ours,' adds Suri. PEB can also be moulded into high-quality architectural designs, at a low cost, with high construction speed. Raghavendran adds, 'The PEB erection process is easy and, further, PEBs are flexible and can be expanded in the future if needed.' PEB also keeps pollution at bay as prefab works are done inside factories. At the construction site, only nuts and bolts are used for erection of structures, without causing air pollution. 'PEB structures can be custom-fabricated according to the stress that the building will experience and, therefore, are effective,' says Raghavendran. These structures also help in saving roofing costs. 'Compared to conventional methods, PEB roofing can reduce time by more than half and eliminate delays of unavailability of skilled manpower,' says Bhasin.

Roofing trends
Galvanised steel sheets have traditionally dominated India's roofing industry. 'For roofing, galvalume sheets are used, the advantages being corrosion-resistance and a warranty of 10-15 years,' says Roy. While he says that every square foot of a structure requires roofing, Garg agrees that PEB would predominantly use metal roofing.

For India's hot and tropical weather, an important element in roofing systems is the ability to reduce thermal heat gain. Raghavendran says, 'The higher the solar reflectivity index, the more heat reflected, which is better to reduce heat transmission.' He says that new trends are being seen in the structural capability of roofing materials, in terms of span-to-weight ratio going up with the introduction of high-strength materials, special interlocking ways, reducing the number of joints and overlaps, etc.

Garg says that new trends are also being seen in coloured fibre cement sheets, coloured metal sheets and, to some extent, poly-coloured sheets, as these are lightweight and don't corrode over a period of exposure.

Cost-effective
Steel is a recyclable material, hence the structures built from steel are also green. The raw material used in PEB itself has a high recycle content. 'Moreover, steel when sold as scrap, results in high resale value,' says Raju. Suri adds, 'PEB structures are energy-efficient, which results in reduced electricity bills.'

Considering all factors, a PEB structure is more economical than an RCC building. Steel roofs also have high longevity. Another important advantage of steel structures is that they are not plagued by leakages. Though the cost of PEB roofs is about Rs 400-450 per sq ft, conventional roofs may cost less. However, Roy takes a long-term view. 'On a life-cycle basis, PEB roofs are cheaper,' he says.

Garg says that PEB roofs are 20 per cent more economical than roofs built with other materials. He elaborates, 'An industrial building with conventional methods would cost about Rs 600-700 per sq ft, whereas PEB will be about Rs 550-600 per sq ft.'

Facing calamities
Since they are light, steel structures are the best non-conventional method to use in seismic zones. 'We delivered a project for Amarpali Banquet Hall in Nepal prior to the earthquake and after the quake it became a place where people came for refuge and stayed,' says Suri. Explaining why PEB structures help in rebuilding disaster-prone cities, Roy says, 'Facilities within the city are not required to rebuild a (disaster-hit) structure.' It's not just earthquake-prone areas. PEB structures can also withstand the impact of floods as witnessed in Chennai and Uttarakhand in India. Apart from being quake-resistant, PEBs are also fire-resistant and have a low or negligible maintenance cost. This saves on the overall building cost. PEB foundations are also cheaper underground due to lighter foundations, says Suri. The Bhasin Group hopes to reduce the per-square-foot cost by about 12.5-15 per cent for its Noida project.

Fresh impetus
Increased awareness is leading to steady growth for PEB structures. There are other factors that are expected to help. First, the projected growth in the economy is expected to trickle down and affect construction activity, and PEB in particular. Second, the new construction boom expected due to the government's Smart Cities programme will also provide a major fillip. Third, prefab structures are gaining popularity in the food and paper industries. Garg lists 'railway workshops, townships, IT buildings, and shopping malls' as new additions to the sectors that will be increasingly using prefab structures.

In fact, PEB buildings have even been recently used as multi-level car parking structures. Raghavendran says, 'In due course, steel buildings that are fire-resistant and thermal-efficient will become common.'

Some developers such as Bhasin are turning to PEB in a big way. 'We find PEB structures easy to construct and deliver in lesser time and at low cost, with savings on early completion,' says Bhasin. He has a caveat, though. Bhasin says that PEB construction should be encouraged by enforcing strict building code rules.

Peeping into the future
Though the advantages of PEB are many and the sector looks to have promising future, there are a few disadvantages that have to be overcome. Among these are price volatility of steel, drop in new investments, a high tax structure and application anomalies. There's also an oversupply in the market when steel prices drop. As Roy says, 'When steel prices drop, people tend to hold back their investments.' Further, no standard code exists for PEB buildings with engineers adopting different norms. Bhasin says, 'We need to develop a standard code. Vendors can play an important role by reducing cost as well as the overall weight of the structure. With not many reputed PEB vendors, monopoly has come to play, which needs to be eliminated.'

However, Raghavendran sees a silver lining. 'There are no major challenges, as the Indian code, which was once not elaborate, now covers PEB structures,' he points out. Clearly, the market seems ready for the introduction of PEB structures in a big way, if these minor anomalies are ironed out.

Case Study by Everest Industries
1. Project summary (key features of the project) This project was a Rs 1,300 crore greenfield integrated cement plant for ACC Cement ( Part of the HOLCIM Swiss group) at Bhilai. Everest's scope in the project included design, supply and erection of four steel buildings for stacking and handling the crucial raw materials for cement like coal, slag, lime and gypsum. The building's house stacker and reclaimers and such have to be large clear spans covering something like two football fields. The buildings span 60 metres clear, column-less and over 20 metres high. The lengths together of all four buildings exceeds 1,000 metres, or say,
1 kilometre. The steel used exceeded 3,400 MT, along with 1,14,200 sq m roof and wall cladding sheeting, 60 m clear span between two columns, 1:2.5 slope, 25 m ridge height, special painting-Sa-2.5,150 micron primer + HBMIO + PU paint 2. Project start and completion date: 22.03.2013 û 23-07-2014
3. Aesthetic, dimensional, occupant comfort and fire safety: Very steep slope, 1,000 m total length, louvered cladding, building height of 20 m at lowest corner. Solid web rafters and dust load handling capability of 100 kg/sq m which meant total load on roof was 2000 MT including live and dead load.
4. Consistency with building code requirements: 100% compliant to IS standards with extraordinary provisions for handling cyclones and dust loads.
5. Cost of the project: Approximately Rs 34 crore.
6. Design parameters for the project:IS 0.1 KN/sq m dead load,0.81 KN/sq m roof live load,39 m/s wind speed, Seismic Zone-ii, Deflection ûHeight-H/100, Length-L/180
7. Materials, colours, structural form, dimensional modularity: ASTM-572 Gr-50, Galvalume sheet
8. Sustainable construction (green construction practices followed such as solid waste management, rainwater harvesting, pollution control, environmental protection): Low VOC paints, recyclable steel used. The safety aspects were configured such as to have 300 accident free days in the whole project. Over 1000 MT steel work was saved due to the use of high tensile steel and solid web technique for such construction.
9. Project quality (adherence to design specifications or technical specifications, quality certifications ù ISO, etc.):
100% specifications for IS standard.
10. Health & safety: Details or copies of any safety certifications or measures or safety records for the project: Impeccable safety record.

Case Study by Interarch
In 2015, Interarch designed and engineered, manufactured and delivered the largest clear span building in India for UltraTech Cement in Rawan. The building is spread over an area of 35,000 sq m. Interarch's scope of work included design and engineering, fabrication, supply and logistics, and erection of four buildings in Rawan, Chhattisgarh. The four buildings required were clear-span buildings ranging from 62 m, 85 m, and 95 m to 99.8 m.

On the basis of customer needs and functional usage, Interarch's expert design and engineering team proposed an open web portal frame structure for the 99.8 m clear span building using CHS sections and the three other buildings in built-up sections. The building was designed for the seismic zone 3 and is IS 800:2007 compatible. The loading design has been applied on the structure in accordance with IS-875 (Part 1, 2 &3).

The pipe structure, once completed, will be one of the biggest milestones in Interarch's recent history. Once erected the building will span 99.8 m wide and 353 m long, with a clear height of 24 m at the peak.

Interarch-certified builders and employees had to work under very stringent quality and safety conditions in line with international standards to achieve many challenges at the site. The erection of the 99.8 m clear span building was done near three operating conveyer belts surrounded by heaps of coal, dust in the environment and lack of space to erect the building caused lot of difficulty to the erection team. Interarch's team had to construct a crossover bridge and constantly spray water to keep the dust settled. All workers wore face masks and safety goggles to tackle the dust.

Interarch deployed almost 15-20 dedicated safety and quality engineers at the site to ensure the highest standards of safety and quality controlled execution. The total time taken for erection of the building was six months.

UltraTech Cement is the largest manufacturer of grey cement, Ready Mix Concrete (RMC) and white cement in India. It is also one of the leading cement producers globally. UltraTech Cement has 12 integrated plants, one clinkerisation plant, 16 grinding units and six bulk terminals. Its operations span across India, UAE, Bahrain, Bangladesh and Sri Lanka. UltraTech Cement is also India's largest exporter of cement reaching out to meet demand in countries around the Indian Ocean and the Middle East.

- Seraphina D'souza

Project Name UltraTech Cement Limited (Unit – Rawan Cement Works)
Project Location Rawan , Chhattisgarh
Building Usage Coal Stacker and Re-claimer Covering Shed
Tonnage 2115 MT
Length 353 m
Width 99.8 m Clear Span
Height 14 m height at eave and 24 m at ridge
Area of Project 35,000 sq m
Project Feature CHS Bracing
10 m bay spacing along the length of the building
Roof slope 1 in 4
Building design as per IS 800-2007
Special tripod CHS portal frame
Pre Galvanized purlin & girts
Shot-blasted structure finished with epoxy paint
Dust load 0.5 KN/sq m on roof
Roof- 0.47 m Tracdek Hi-Rib bare Galvalume (550 Mpa)
Wall- 0.50 M Tracdek Hi-Rib color coated Galvalume (550 Mpa)
 
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