Merit Award - $75 million to $200 million

Modularization brought a new 80,000-sq.-ft concourse in for a speedy landing on a challenging site at Dallas-Ft. Worth International Airport (DFW).

The project involved the demolition and replacement of four gates, known as the High C Gates, at DFW’s Terminal C. The new 80,000-sq.-ft concourse consists of six individual modules, roughly 84 ft by 84 ft, constructed roughly one mile away using conventional steel framing that were then moved to the terminal site using SPMTs (self-propelled modular transporters) and set on concrete columns. Once the modules were set in place, additional steel framing was erected to fill in the gaps between a few of the modules. This method allowed for the modules to be constructed while the existing buildings were demolished and foundations and supporting columns were installed, reducing the schedule by 22%.

Each module was designed to be structurally sufficient when freestanding at the fabrication yard, during transport on the SPMTs, and as part of the overall concourse at the terminal site. For this design concept to work, the system for lateral forces and the system for gravity forces required creative solutions. Laterally, each module was stabilized using a combination of braced frames and moment frames to create freestanding modules. The modules were then stitched together at the terminal site so the individual lateral systems could work in conjunction. At both the fabrication yard and the terminal site, a traditional gravity load path was followed, with all loads ultimately being transferred from the deck to beams, then to the columns that transfer the loads to the foundations.

Some columns at the terminal site could not be installed until after a module had been moved into place because they were in the direct path of the SPMTs, which could only support a module at the terminal site for a set amount of time before they had to be returned to the fabrication yard to transport the next module. Because of the time constraint, the team created a composite column concept, with the steel portion of the column designed to support the module when it was on the SPMT. Once the steel column was placed and the transporter released the module, concrete was poured around the steel column to create a composite column that could support full lateral and building service loads.

In addition to designing concourse girders that could support the weight of the module during transport, the team also analyzed possible overturning moments due to wind and the acceleration or deceleration of the SPMTs. Friction at the surface where the concourse girders were in contact with the SPMTs helped prevent the modules from sliding off during transport.

To further expedite the project schedule, the roof, exterior walls, metal panel system, and curtain walls, along with some mechanical shafts and pipes, were installed on the modules at the fabrication yard. This required additional coordination with the manufacturing of those systems and further analysis of the structure to ensure that any unintended deflections that might occur when the modules were being transported or transitioned would not damage the metal panel system or the glass in the curtain walls.

Judge comment: “This modular installation is a great way to showcase the efficiency of using steel in a tightly constrained site in an efficient speed-to-market application--and the adaptability of this material to create these modular sections that create open, long-span areas that can be quickly and efficiently assembled.” -David Horowitz, executive vice president, AECOM Tishman

Owner: DFW Airport, Dallas
General contractor: The Walsh Group, Chicago
Architect: PGAL, Addison, Texas
Structural engineer: Henderson Rogers Structural Engineers, LLC, Houston
Consultant: Mammoet, Rosharon, Texas
Steel fabricator, detailer, and bender/roller: Miscellaneous Steel Industries, Kyle, Texas *AISC full member; AISC-Certified building fabricator*
Steel erector: Acero Construction Services, Kyle, Texas