NSC executed the erection of a highly complex, architecturally expressive terminal structure—delivering 15,000+ tons of structural steel and 800,000 sq. ft. of metal deck while building directly over active tunnels and passenger systems.
Structural Steel Erection
Erected approximately 15,200 tons of structural steel for the new, three-story terminal building, including long-span roof framing and transfer structures over active infrastructure.
Installed 38 Architecturally Exposed Structural Steel (AESS) Category 1 tree and quad columns, supporting the terminal’s signature rolling roof form.
AESS tree columns spaced up to 120 ft on center, forming a primary architectural and structural feature at the landside entry.
Roof structure includes 5-ft-deep plate girder “spine” girders spanning up to 120 ft, supported at branch tips with approximately 30 ft spreads.
Roof framing integrates wide-flange members and double-angle diaphragm bracing aligned to the roof curvature, requiring tight geometric control during erection.
Executed erection of roof framing with approximately 60-ft cantilevers beyond the building façade to shelter curbside drop-off areas.
Building Over Active Infrastructure
Performed steel erection directly above active utility tunnels and the existing people-mover (APM) systems, which remained fully operational throughout construction.
Installed long-span grade beams and transfer girders—some extending up to 70 ft—to redistribute column loads away from tunnel zones.
Set embedded plate girders up to 5 ft deep, fabricated from 50 ksi wide-flange and plate material, integrated compositely with concrete slabs to maximize capacity within limited depth constraints.
Coordinated erection sequencing to maintain tunnel access, load limits, and clearance requirements without disrupting airport operations.
AESS Fabrication & Erection Challenges
Tree columns fabricated from four 20-in-diameter round steel sections, press-brake formed from 1½-in plate, bundled into trunks measuring approximately 44 in × 44 in out-to-out.
Branches taper from 20 in to 14 in diameter, with geometry varying by location to preserve the organic architectural form.
Field-spliced branch-to-trunk connections completed using all-around CJP welds, exposed to view and meeting AESS Category 1 visual requirements.
NSC utilized temporary steel falsework and shoring towers to support branches during fit-up, allowing fine adjustment of top-of-branch elevations prior to final welding.
Roof girders and beams were pre-assembled on grade and lifted into position onto shoring systems before tensioning bolted connections and completing field welds.
Surveying, Fit-Up & Surveying
Employed cloud-scanning and precision survey control throughout erection to verify geometry against the engineered model.
Adjusted branch elevations after roof framing installation to achieve final alignment prior to CJP welding.
Post-erection surveys confirmed actual deflections aligned with structural analysis predictions.
Tight tolerances required due to lack of expansion joints within the roof framing system and the interdependence of column and roof geometry.
