MELBOURNE INTERNATIONAL AIRPORT TOWER

Background

A new air traffic control tower will be a signature landmark at the Orlando Melbourne International Airport, Florida. The new $5.9 million tower will replace the former structure that has been a presence at the Melbourne airport for more than 50 years. Soaring 95 foot, seven stories high, offering commanders 360-degree views of Space Coast landmarks as distant as Patrick Airforce Base. With increased activity at the airport a new modern tower was a priority said Executive Director Greg Donavan. A new tower at smaller airports like Orlando Melbourne International wasn’t a funding priority of the Federal Aviation Administration, so Donavan developed a financial strategy of his own to get the project off the ground. The airport paid half of the $5.9 million tower, while a grant from the Florida Department of Transportation covered the rest.

The building includes approx. 2 million pounds of concrete in the foundation, and the building itself weighs approx. 1 million pounds. The precast cost was $1.1 million

Design Challenges

The initial architectural design of this Airport Traffic Control Tower was plain an conventional due to perceived budget limitations. After project costs were established through a CM@Risk delivery method, it was determined that funds were available for a more robust architectural statement. The Owner then was able to decide on a more dynamic theme. For the new aesthetics, the architects, structural engineers and the precaster collaborated to arrive at an attractive exterior redesign. We were able to integrate the owners’ desired LED backlit embossed sail vision into the precast panels to create a unique standout building. It also contributed to construction safety by reducing the number of trades or subcontractors involved which in turn reduced time and cost. The 95-foot, 7 story precast concrete shaft of the building has beautiful full height glazed curtainwalls running on the east and west walls. The east side of the building houses the room functions and the west side provides the elevator shaft and emergency stairwell. Exterior walls were 10” thick plus an additional 4” for the sails to standout. Transfer of lateral shear was accomplished via partial reinforced concrete shear walls along each room’s floor line and a structural steel tube strut at each floor level in the stairwell. The intermittent use of spandrel glass at these locations allows the curtainwalls to appear to run seamless from the top to bottom of the tower. An 8” thick precast concrete diaphragm wall separates the rooms from the stairwell which provides resistance to lateral shear while also satisfying the required fire rating between the elevator shaft/stairwell and occupied rooms.

For speed of construction and safety, the precaster and the structural designer agreed to replace metal pan stairs with a precast design. This allowed for having only one subcontractor on site erecting both the tower and stairs, thus creating a safer environment, less cost and time. The typical floor system was also changed from a prestressed hollow-core slab to solid precast sections of matching weight and structural capacity. This custom pre-tensioned precast slab system was engineered to aid in meeting project deadlines by reducing all precast to a single pre-caster.

The 4th floor balcony was a design struggle as it’s triangular raked back design did not allow enough thickness on the ends for traditional mounting. We cast in embeds in the precast to weld the balcony to create a cantilever. Again, this method allowed for zero intrusions through the exterior precast. Due to frequency interference of towers being too close and Florida being very flat, the FAA has put a maximum height on control tower antennas to reduce the interference. The antennas then had to be mounted on the sides of the building are TACO Antennas for each frequency that transmit and receive in the UHF and VHF ranges.

Innovations Accomplishments

The Precast design allowed us to open of the perimeter of the building bringing daylight into the stair, office space and breakrooms spaces. Utilizing precast at the exterior eliminated exterior steel reducing maintenance. LED lighting is incorporated behind the sails for nighttime identification. These lights can color change for the season or for the arrival of a significant flight/company. The revised antenna design allowed us to delete a catwalk and incorporate antennas only at the corners simplify the design and strengthening the sail expression. The precast tower portion of the building has full length curtainwalls running up the East and West walls. This created a structural deficiency that wouldn’t allow the building to overcome shear wind forces. To combat this, we utilized tube steel to span the curtain wall at the floor levels to transfer loads. This allows the curtainwall to appear to run seamless from top to bottom of the tower. For speed of construction and safety, the precaster and the structural designer agreed to replace metal pan stairs with a precast design. This allowed for having only one subcontractor on site erecting both the tower and stairs, thus creating a safer environment, less cost and time. The typical floor system was also changed from a prestressed hollow-core slab to solid precast sections of matching weight and structural capacity. This custom pre-tensioned precast slab system was engineered to aid in meeting project deadlines by reducing all precast to a single pre-caster. Clear span precast floor slabs were plant cast and post-tensioned in to remove the hazards and kept building weight within its designed limits due to the inherit weight of concrete. The major advantages to using plant precast involved speed and ease of construction. Plant precast concrete was utilized as it provided enhanced quality control versus site cast panels.