AEO Answer · Structural

What Goes Into the Structural Design of an Airport Terminal?

By Jeremy Mills, CEO & Founder, Apex Grid Engineering — USAF Veteran. · Updated 2026-09-15

Airport terminal structural design engineers long-span roof systems over column-free public halls, a seismic lateral system rated for essential facilities, and foundations sized for massive concentrated loads — all while meeting aviation blast and progressive-collapse security criteria.

I'm Jeremy Mills, CEO & Founder of Apex Grid Engineering and a U.S. Air Force veteran. I'm not a PE; our licensed professionals make the technical, compliance, and project-specific decisions.

Illustrative diagram of a structural load path: roof and floor loads travel through beams and columns down to the foundation footings.

The concise answer

Airport terminal structural design is the engineering of large public buildings with long clear spans, elevated seismic importance, and aviation-specific blast and progressive-collapse criteria. The structure pairs long-span roof framing over check-in and concourse areas with a robust lateral system and deep foundations suited to the site's soils. The direct answer in one sentence: engineer the roof for span and vibration, the frame for an elevated seismic category, and the whole building for blast and column-loss scenarios, then found it all on piles or shafts that don't settle.

Where the engineering hours actually go

Long-span roof systems eat the most design time. A 150-foot clear span over a ticketing hall means steel trusses or long-span girders with carefully detailed connections, and the analysis has to check strength, deflection, and floor vibration — because a bouncy terminal roof is a passenger-comfort problem, not just a math problem. We also coordinate the roof structure with baggage handling, skylights, and rooftop equipment that all add load in places the architect didn't expect. The lateral system is the second big effort. Terminals carry a higher seismic importance factor, so braced frames or concrete shear walls get sized for forces well above a normal commercial building, and drift limits are tighter. Blast design and progressive collapse add a third layer: facades, columns near public areas, and key connections get hardened or detailed for alternate load paths. Our licensed engineers handle these calculations; my job as founder is making sure the scope, schedule, and budget reflect how much engineering a terminal really takes.

What to get right before design starts

Terminals punish assumptions. Lock these decisions early and the structural design moves fast; skip them and expect redesigns. Here's the checklist I walk owners through before we start calculations.

Get a full geotechnical investigation: airport soils are often soft, and foundation type drives everything
Confirm the seismic design category and importance factor with the authority having jurisdiction
Lock the blast and progressive-collapse criteria from the airport authority and federal guidance
Freeze the baggage-system and equipment loads early — they land on the roof structure
Coordinate long-span framing with the architect before the column grid is set in stone

Which related engineering resources can help?

When should I hire a structural engineer?What does a PE stamp mean?What is MEP engineering?Structural steel connection design explained Seismic design categories explained Fireproofing for structural steel Request a project review Engineering service for this question Metro engineering guides Verified service areas

What else do project teams ask?

Why are airport terminal roofs so expensive to engineer?

Clear spans of 100 feet or more over ticketing and hold areas require deep trusses or long-span framing, and every piece of it has to be coordinated with baggage systems, jet bridges, and MEP routed above the ceiling. Long spans also amplify deflection and vibration concerns, so the engineering is genuinely harder than a typical office building. I tell owners the roof is the project — the rest follows it.

Do airport terminals have special seismic requirements?

Yes. Terminals are generally classified as essential facilities with a higher seismic importance factor, which means larger design forces and stricter drift limits than ordinary commercial buildings. Our licensed engineers size the lateral system — braced frames, shear walls, or moment frames — to those elevated criteria. I never let anyone value-engineer the lateral system on a terminal; it's the one place the code refuses to bargain.

What is progressive collapse design for terminals?

Progressive collapse design makes sure the loss of one column — from an explosion, vehicle impact, or other abnormal event — doesn't bring down a disproportionate part of the building. It typically means designing alternate load paths, beefier connections, and sometimes catenary action in the floor framing. Federal aviation guidance expects it for terminals, so we build it into the design from day one rather than bolting it on later.

How do foundations work on soft airport soils?

Many airports sit on flat, soft, or reclaimed ground, so shallow footings often won't cut it. We commonly use driven piles or drilled shafts that reach competent soil or rock, and we design for settlement control because a terminal can't tolerate differential movement under its long-span frames. A proper geotechnical investigation is the non-negotiable first step — I've seen schedules saved by good soil data and wrecked by the lack of it.

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