1 Steel for complex city builds: The big picture

In Indian metros, developers and operators are stacking data centers, offices, retail and infrastructure on top of each other, often above basements, roads and rail or in very narrow plots. Traditional reinforced concrete can become deep and heavy for long spans and transfers, which adds cost to foundations, increases storey heights and complicates service coordination.

What steel brings to these environments

• High strength to weight ratio. Steel beams, trusses and girders achieve 15 to 50 meter spans with less depth and weight than equivalent concrete members.
• Prefabrication and modularity. Offsite fabrication allows faster erection, better quality control and shorter time on congested urban sites.
• Service integration. Cellular beams, composite beams and trusses can be detailed with large openings to pass ducts and cable trays without constant beam notches.
• Adaptability. Bolted connections and demountable elements support future changes of use, new equipment or additional floors.

Industry commentary on prefabricated steel for data centers notes that these advantages are particularly powerful when speed to market and column free space are business critical.

2 Long span steel in Indian metros

Long span structures are often defined as spans above 15 to 20 meters, which quickly appear in auditoriums, atria, industrial sheds, data halls, exhibition spaces and transfer floors. In Indian city projects, spans in the 15 to 30 meter range are common for podiums and data halls, while larger spans appear in special use buildings and terminals.

Common long span steel systems and where they fit

• Rolled and built up beams. I and H beams, plate girders and cellular beams in composite construction with concrete slabs for 12 to 25 meter spans, good for offices, data halls and parking decks.
• Trusses. Roof trusses, Vierendeel trusses and storey deep trusses for 20 to 40 meter spans where roof profiles or facade grids can accommodate deeper members.
• Pre engineered frames. PEB style portals used in industrial and data center shells at metro edges, especially in Pune, Hyderabad and Ahmedabad.

Good practice includes control of deflection and vibration, coordination of openings and shear studs, and careful fire protection strategies for exposed or partially exposed steel.

3 Rooftop steel structures for plant, amenities and telecom

Rooftops in Mumbai, Chennai, Bengaluru, Delhi NCR and other metros are increasingly valuable for HVAC plant, generators, solar, telecom towers, rooftop restaurants and amenity decks. Steel is well suited for these uses because it adds relatively little weight to existing structures and can be assembled with limited disruption on busy buildings.

Key rooftop steel typologies

• Plant platforms. Grillage frames and plinth beams that carry chillers, cooling towers, AHUs, generators and large ductwork, often with vibration isolation and access grating.
• Amenity and shade structures. Lightweight canopies, pergolas and pavilions that turn roofs into cafeterias, terraces and breakout spaces, especially on IT campuses and commercial towers.
• Telecom and equipment towers. Lattice masts and rooftop telecom structures that must manage wind, seismic and dynamic effects without overstressing existing columns.

Rooftop steel design in Indian metros must address wind uplift, corrosion, drainage, waterproofing interfaces and safe access for maintenance from the outset.

4 Steel transfer structures above roads, basements and public space

Transfer structures change the path of gravity loads when column grids above do not align with supports below, a common scenario in city projects with basements, roads, metro boxes or retail at ground level. Steel transfer systems can often stay shallower and more buildable than deep concrete transfer beams, particularly when services must pass through the same zone.

Typical steel based transfer strategies

• Storey deep transfer trusses. Steel trusses that span over lobbies, driveways and metro boxes, supporting several storeys of structure above while leaving space for services within the truss depth.
• Transfer girders and cellular beams. Plate girders or cellular beams that carry stacks of columns above while allowing ducts and cable trays to pass through web openings.
• Composite transfer frames. Steel beams or frames combined with concrete slabs or topping for stiffness, often used where fire rating and vibration performance are critical.

Transfer design must consider construction staging, temporary supports, differential deflection and robustness, especially in seismic or high risk zones.

5 City patterns: Mumbai, Chennai, Bengaluru, Delhi, Hyderabad, Pune, Ahmedabad and Kolkata

Although the underlying engineering principles stay the same, the way long span, rooftop and transfer steel is used varies across Indian metros because of land, climate, regulation and local supply chains. Treating each metro as a pattern helps design teams choose realistic steel solutions that contractors can actually build.

Mumbai: Vertical towers, podiums and coastal exposure

• Use long span composite beams and trusses to bridge over basements and podiums, carrying data halls, offices or amenities above active driveways and parking.
• Design rooftop steel decks and telecom structures with corrosion resistant coatings and careful detailing against marine air and high winds.
• Integrate steel features and canopies along key roads to give dense commercial and data center projects a strong visual identity.

Chennai: Coastal hubs, cable landings and plant decks

• Deploy steel for long span plantrooms and trestles that carry cooling and power systems above flood prone ground levels.
• Use rooftop steel frames to support air cooled equipment, louvers and screening that protect from sun and saline winds.
• Coordinate steel supports for submarine cable routes, trays and risers within BIM models to avoid clashes in tight corridors.

Bengaluru: Campus bridges, atria and amenity roofs

• Exploit long span steel bridges and link structures between blocks on tech campuses for shared amenities and services.
• Use steel roofs and trusses over atria, food courts and collaboration zones that sit next to or above data halls and offices.
• Plan rooftop steel for solar, plant and public terraces where climate allows comfortable outdoor use for much of the year.

Delhi NCR: Power corridors, security structures and air quality

• Use steel canopies and portal frames at secure entries and screening zones on DC and logistics campuses near expressways.
• Detail long span steel around substations and switchyards where clear spans and heavy equipment handling are critical.
• Place rooftop steel intakes and exhaust structures to manage polluted air and recirculation while respecting height and setback controls.

Hyderabad: Greenfield campuses with modular steel

• Standardise long span steel hall modules and rooftop decks across multi building DC and IT campuses to accelerate subsequent phases.
• Combine steel frames with precast or composite slabs for repeatable, fast to close envelopes.
• Allow for future steel expansions and mezzanines in early structural grids as demand grows.

Pune: Industrial sheds, mezzanines and crane beams

• Use long span steel frames and PEBs for DC shells, industrial buildings and logistics facilities that share the same campuses.
• Design mezzanines and crane beams in steel to support manufacturing, warehousing and DC support spaces with maximum flexibility.
• Plan rooftop steel for plant on low rise sheds, balancing access, vibration and wind resistance.

Ahmedabad: Steel frames near logistics and GIFT City

• Adopt long span steel frames and PEBs along industrial corridors for DCs linked to warehouses and factories.
• Use steel transfer beams where DC blocks sit above parking or mixed use ground floors in and around GIFT City.
• Coordinate rooftop steel for telecom, solar and plant with grid and regulatory requirements specific to financial zones.

Kolkata: Lightweight steel, retrofits and rooftop additions

• Use lightweight steel for rooftop plant platforms and small long span infill structures on older buildings in Salt Lake and New Town.
• Combine steel with existing concrete frames for transfer structures over lobbies and driveways in retrofit projects.
• Plan telecom and edge computing structures on roofs with attention to seismic, wind and corrosion in a humid, coastal influenced climate.

6 BIM and digital engineering for long span, rooftop and transfer steel

Long span, rooftop and transfer steel all sit in the most congested parts of a building, where structure, services, architecture and operations overlap. BIM and digital engineering are essential for understanding how steel, concrete and MEP interact in three dimensions over time.

How to use BIM to de risk complex steel

• Model steelwork, concrete, services, facades and equipment at appropriate LOD so openings, connections and tolerances are clear before fabrication.
• Run Navisworks style clash detection and constructability reviews, focusing on transfer zones, plantrooms, rooftops and major long span areas.
• Use 4D sequences to plan crane locations, lifting paths and erection phases on tight metro sites where road closures and night working are common.

Articles such as digital engineering in data centers and clash detection and risk mitigation show how these digital workflows translate directly into fewer surprises on complex steel projects.

7 How J&F India supports steel engineering on complex city builds

J&F India works with developers, data center operators, industrial clients and architects to integrate steel, concrete and BIM on complex city projects across Indian metros. Internal resources on complete engineering project, data center engineering services, BIM modelling services, BIM coordination services, Navisworks clash detection services, BIM auditing and consulting and proof checking outline the full toolkit.

What this looks like in practice

• Long span and transfer design that respects local seismic, wind and fire requirements while staying buildable on tight urban sites.
• Rooftop steel and plant platforms coordinated with structure, waterproofing, access and MEP for both new builds and retrofits.
• Independent model audits and proof checks for investors, lenders and operators who need extra assurance on complex steel solutions.

For organisations planning complex city builds in Mumbai, Chennai, Bengaluru, Delhi, Hyderabad, Pune, Ahmedabad and Kolkata, combining well engineered steel with strong BIM and digital workflows is one of the fastest ways to unlock capacity, control risk and keep options open for the future.