India’s aviation sector is experiencing unprecedented growth, with passenger traffic expected to surpass pre-pandemic levels and the number of operational airports steadily rising. As part of this expansion, the country is investing heavily in modernising airport infrastructure to accommodate increasing demand. A key challenge in this development is designing terminals that balance efficiency, sustainability, and passenger experience, all while adhering to tight construction timelines.
SSMB speaks to experts who explore the role of steel in shaping modern airport terminals, the challenges of long-span construction, and the innovative solutions that are setting new benchmarks in aviation infrastructure.
Open Skies
As airports evolve to accommodate increasing passenger volumes and advancing technologies, the need for efficient, adaptable terminal spaces has never been greater.
Gautam Suri, Whole Time Director, Interarch Building Products Ltd, states, “Airports use steel for construction, both for the terminal building and, primarily, the roof. This is because airports require large-span roofs that cover almost the entire expanse of the airport — from kerb-side to check-in to security to departure.”
Client side stakeholders like Bengaluru International Airport Ltd (BIAL) prioritise smooth passenger flow while creating an inviting and memorable environment. Sundar Chandramouli, Vice President – Special Projects, BIAL says, “From a user perspective, modern terminal buildings are increasingly prioritising flexibility in floor space utilisation. This trend highlights the growing demand for large-span, column-free structures, particularly in key areas like departures and arrivals. Such designs not only facilitate efficient floor area planning but also allow seamless adaptation to evolving needs.”
For example, airports are transitioning from paper-based check-in systems to digital check-in systems, incorporating technologies like DigiYatra. This shift necessitates constant repurposing of spaces, which requires unrestricted floor usage. Therefore, column-free spaces and large-span structures are essential for the future of terminal buildings.
When it comes to operational efficiency, column-free spaces play a crucial role, making large-span structures a necessity. However, with the adoption of such expansive, open designs in terminal buildings, there is a potential challenge: a lack of visual distinction. This can lead to a uniformity in appearance, from signage to check-in and check-out systems, risking a loss of unique identity and character in the space.
The only area where architectural expression can create a unique identity is the roof structure. Making the roof shape iconic — whether it’s an arched roof, a lotus-shaped roof, or any other distinctive design — can provide a terminal with a unique identity. He adds, “This not only enhances the airport’s visual appeal but also makes it a source of pride and an instantly recognisable landmark. I believe this is a crucial element in building a strong and distinctive brand identity for the airport.”
From a structural point of view, Saurabh Sharma, Managing Director, Buildsworth Solutions Pvt Ltd, highlights that the primary challenge lies in the connections of various shapes and angles. “Nowadays, architects are highly innovative in terms of roofing designs. For instance, they often incorporate several saddle flares in the roof profile. These connections pose a significant challenge for consultants as they need to account for wind forces, earthquake forces, heavy loading, and efficiently transfer these loads to the RCC connection at the top of the columns.”
The shape, cantilever projections, and their transfer to the supporting structure below are some of the key challenges for structural engineers. At the same time, steel is the only material capable of addressing these challenges due to its flexibility, ductility, toughness, and ease of fabrication. These properties make steel the ideal choice for such complex structural requirements.
Speedy Solutions
The sheer scale and complexity of building such vast, unobstructed spaces in a live airport environment comes with its own set of challenges. Chandramouli says, “When we talk about quality and safety, our goal is to minimise on-site activities, especially in a live airport environment where people are constantly moving, and operations are ongoing. We aim to reduce time exposure by conducting risk analyses and taking proactive measures.”
Gautam Suri, though, points out, “In most cases, these structures remain exposed rather than being covered, adding to the aesthetic appeal. In standard steel pre-fabrication, connections are typically made using bolted end plates. However, in airport structures, these bolted connections are not preferred, as many architects and consultants do not find them aesthetically suitable. As a result, the joints in the primary structural members — such as the portal members or main rafters — often need to be welded.”
This introduces a major challenge: since these are welded joints, the structural elements must be transported in discrete segments and welded on-site. Transportation constraints limit the size of each segment, typically to a maximum of around 12 m in length. Alternatively, the segments can be fabricated on-site, then welded and assembled into a complete structure.
Due to these complexities, airport roof structures may not be ideally suited for pre-engineered off-site manufacturing. Suri adds, “Pre-engineered construction means that no fabrication is done on-site; everything is pre-manufactured and assembled at the location. However, with airport structures, even if pre-engineered components are supplied, on-site welding is still required. On-site welding presents additional challenges, including maintaining quality, ensuring precise fabrication, and implementing stringent quality control measures.”
Chandramouli presents a possible solution, “To achieve this, we have collaborated with vendors and partners, asking them, ‘How much can be done off-site?’ The focus is on bringing components in an assembled or semi-assembled manner, spending minimal time on-site to install them, and quickly making the facility operational.” This approach ensures that most of the work happens in a controlled factory environment, where quality can be better managed.
Material Matters
As airports continue to expand to accommodate increasing passenger traffic and operational demands, speed and efficiency in construction have become critical factors. Maximising steel’s potential in such projects requires a deep understanding of structural behavior, material selection, and fabrication techniques.
For Chandramouli’s part, he says, “In terms of safety standards, coupled with the business demands and the rapid growth of the aviation industry, our management prioritises fast-track construction and swift turnaround of spaces. To achieve such efficiency, what better material to rely on than steel? Its versatility and speed of construction make it the ideal choice.”
Steel undoubtedly plays a significant role in meeting the growing capacity and demand for infrastructure facilities, especially terminal buildings. When it comes to enhancing an airport’s functionality, this extends to the creation of aircraft hangars and specialised MRO (Maintenance, Repair, and Overhaul) facilities. These infrastructures demand rapid construction and large-span designs to meet operational requirements efficiently. In such cases, steel emerges as the perfect material, offering the strength and adaptability needed for swift and effective development.
On the technical side of things, Sharma says, “The important criterion is the moment of inertia. Essentially, what we do is simulate a structure with a load and its combinations. Another key task is to understand how the load is applied and the nature of the load. If it involves moments, we rely on the moment of inertia. If it is axial force, we depend on the sectional area.”
Based on factors such as sectional area, moment of inertia, and torsion, the structure is analysed. These criteria guide the selection of materials based on their properties and performance. He further adds, “For example, hollow sections perform well under axial forces, so we use them in such cases. For moments, we opt for deeper sections, which could be I-sections or box sections, but not SHS (square hollow sections). Instead, we might use RHS (rectangular hollow sections).”
It’s not just about the shape but also the material grade, as a higher grade increases the capacity of the member to withstand stress and improves its strength.
Gautam Suri emphasises on minimising on-site work, “What we manufacture in our plants is produced under a factory environment with strict quality control and high precision, achieved through both qualified and trained welders and specialised equipment. Quality and precision are maintained in the plant.”
However, if some fabrication has to be done on-site, quality and precision suffer because it becomes a site-dependent process. He adds, “Welding is ultimately a manual process, and its quality depends on the skill of the welder and how well he performs the task. Welding in steel structure, specially at connections, is not automated, requiring highly skilled welders and extensive quality checks at the site to ensure high quality welds” This necessitates a lot of testing and strict monitoring at site.
In contrast, welding in a plant environment follows a well-established system with rigorous quality control. Since the entire process is integrated into the plant’s workflow, it happens almost robotically, ensuring consistent quality and precision.
With a plant-manufactured structure, quality and precision are nearly guaranteed. However, with a site-fabricated structure, achieving the same level of quality requires significant effort. Site teams usually consist of contract workers who are not part of a structured manufacturing system. While it is possible to establish a system at the site, it does not offer the same level of precision and control as a dedicated manufacturing facility.
Balancing Act
Building large-scale airport structures requires a delicate balance between structural integrity and construction efficiency. Given the complexity of long-span roofs and terminal buildings, Sharma says, “Through the software available to us, we model the structure as accurately as possible based on the architectural design. We then apply the actual loads and analyse how the stresses are distributed. This is the only way we can simulate the situation, whether it’s at the top of the structure or any other part of the airport.”
However, precise modelling is just the first step. To ensure both efficiency and material optimisation, engineers must carefully select and refine structural components. He adds that steel offers greater flexibility in optimisation compared to concrete, where reinforcement placement is more rigid and difficult to adjust. In concrete structures, reinforcement cannot be curtailed at precise intervals, such as every metre or every 10–12 m. Steel, on the other hand, allows for fine-tuned optimisation, making it possible to adjust thickness and cross-sections while maintaining structural integrity.
“For example,” he says, “if I’m opting for a steel truss and using a hollow section with dimensions of 200 x 300, we have various options for thickness: 3.54 mm, 5.26 mm, 8 mm, 10 mm, 12 mm, or 16 mm. This allows us to maintain the same external shape while reducing the thickness of the cross-section. In this way, optimisation becomes possible in steel.”
Achieving this level of optimisation is not dependent on cutting-edge technology but rather on advanced analytical methods. Structural engineers rely on well-established matrix analysis and finite element methods to assess stress distribution and optimise material use. These methods are applied through widely used software such as SAP and ETABS, allowing engineers to fine-tune structural performance.
A Cut Above
Ensuring precision and quality control in steel fabrication is critical for large-scale airport infrastructure. To achieve this, manufacturing takes place in a highly controlled plant environment equipped with advanced machinery, ensuring exceptional accuracy at every stage of production.
Gautam Suri highlights that the process relies heavily on CNC-controlled machines, with raw materials primarily consisting of steel plates rather than standard hot-rolled sections. He says, “We start with steel plates, which are cut to the required sizes using CNC machines and laser cutting technology. These cut plates are then welded together with high precision using CNC-controlled welding machines.”
“The level of tolerance and control in our process is exceptionally high, and our production speed is equally impressive. Since our plant operates like a production line rather than a traditional fabrication yard, we achieve a consistently high output of steel structures on a daily basis.”
Every component undergoes rigorous quality checks, covering dimensions, punching, hole alignment for bolting, and weld integrity. Various testing methods, including ultrasonic testing, dye penetrant testing, and radiography, help verify the strength and reliability of each weld. Because these tests take place in a controlled setting, any potential issues can be identified and corrected early, ensuring consistently high standards.
Since these tests are conducted in a controlled plant environment, they can be performed efficiently. He highlights, “However, conducting radiography on an already erected structure at the site presents significant challenges. Similar to a medical X-ray, radiography is used to inspect welds in steel structures rather than the human body.”
While a plant setting ensures that all quality control measures are systematically implemented, maintaining the same level of precision and monitoring at a construction site becomes far more difficult.
Quote
“In terms of safety standards, coupled with the business demands and the rapid growth of the aviation industry, our management prioritises fast-track construction and swift turnaround of spaces.”
– Sundar Chandramouli, Vice President – Special Projects, Bengaluru International Airport Ltd
“On-site welding presents additional challenges, including maintaining quality, ensuring precise fabrication, and implementing stringent quality control measures.”
– Gautam Suri, Whole Time Director, Interarch Building Products Ltd
“Nowadays, architects are highly innovative in terms of roofing designs. For instance, they often incorporate several saddle flares in the roof profile. These connections pose a significant challenge for consultants.”
– Saurabh Sharma, Managing Director, Buildsworth Solutions Pvt Ltd
