Army Advances With Precast Concrete

Advanced Individual Training Barrack Phase II, Fort Gordon, Augusta, Ga.

BY MONICA SCHULTES

The innovative use of precast concrete met the building’s demanding design requirements while simultaneously featuring architectural exterior finishes. The structure was designed to resist the concussive force from explosion and to not progressively collapse if one of the pieces was damaged.

“Precast concrete was a good fit for the barracks project to meet blast requirements and progressive collapse,” says Hassan Anvari, chief operating officer for EDT Constructors/Engineering Design Technologies in Marietta, Ga. “It significantly expedited the time required to construct the building.”

Concussive Forces

Meeting the blast requirement was very challenging, requiring detailed analysis and innovative methods. “The majority of detailing was atypical for precast construction and required creative methods to ensure overall building resistance to progressive collapse,” recalls Anvari.

He explains that the original design was based on three spans of hollow-core slabs. However, this configuration would not allow the use of tie-force method. The only viable option was to use the alternate path method for progressive-collapse-resistant design. Using precast concrete bulb tees made it possible to span the building with one precast concrete member. To comply with the design requirements, complicated detailing was necessary to enable the structure to span the “lost” structural member and prevent a progressive collapse. The standard double tee was not adequate, due to limitations to the maximum allowable depth.

Creative Application of Bulb Tees

“The bulb tees also enabled a wide-open floor plan, which allowed us to remove interior columns and beams. The alternate system eliminated interior framing, foundations, and greatly reduced the number of precast components required, which saves time and money while also providing a more versatile structure for the barracks,” says Matt Goodwin, project manager at Tindall Corporation in Conley, Ga. “The bulb tees can withstand higher loads on longer spans versus traditional double tees.”

The open floor plan was reflected on each floor of the barracks. A heavily reinforced topping slab was required on the bulb tees to accommodate the progressive collapse requirements. Additionally, there was an increase in the number and size of the connections throughout the precast concrete to accommodate the extra forces to withstand the concussive blast resistance.

“To comply with the design requirements, complicated detailing was necessary to enable the structure to span the “lost” structural member and prevent a progressive collapse.”

Reduced Life Cycle Costs

In addition to blast and progressive collapse, another important feature was fire resistance. The use of precast concrete eliminated the need for fireproofing and the associated process, which is an intricate, intrusive, and costly operation.

The Army Corps of Engineers (ACOE) values reduced life-cycle cost, especially through thermal efficiency in their buildings. “Use of 14-inch insulated precast wall panels allowed us to exceed R-21 insulation and provide a continuous thermal envelope with no thermal bridge,” says Anvari.

Sound attenuation between rooms was also important to the ACOE for their trainees to avoid hearing noise in adjacent rooms. The ability to deflect or absorb sound also makes precast concrete a smart acoustic material.

Some of the challenges the ACOE faced were dealing with multiple contractors within one construction zone and construction laydown areas that impacted training. Precast concrete components were cast off-site at Tindall Corporation’s production facility, minimizing the impact on Fort Gordon and avoiding encroachment on restricted laydown areas.

With schedule such a critical factor, using precast concrete panels with inlaid brick and articulated multicolor finishes eliminated the need for masonry and other subcontractors. This also reduced possible additional construction hazards, such as extensive scaffolding and material handling for brick veneer construction.

PROJECT SPOTLIGHT

ADVANCED INDIVIDUAL TRAINING BARRACKS PHASE II, FORT GORDON

LOCATION: Augusta, Ga.

Designer: U.S. Army Corps of Engineers, Savannah District, Ga.

Owner: U.S. Army Corps of Engineers, Savannah District

Engineer: Engineering Design Technologies, Marietta, Ga.

Contractor: Caddell Construction, Montgomery, Ala.

PCI-Certified Precast Concrete Producer: Tindall Corp, Conley, Ga.

PCI-Certified Precast Concrete Erector: Bass Precast Erecting, Cleveland, Ga.

Precast Concrete Components: 300,000 ft 2 or 758 pieces, including 270 bulb tees, 268 14-in. insulated wall panels, 84 12-in. insulated wall panels, 60 12-in. shear walls, 51 8-in. wall panels, and 25 flat slabs

The barracks are flanked by smaller precast concrete support structures, one building for lawn care and maintenance and the other for a geothermal steam system.

To match the adjacent structures, the ACOE worked closely with Tindall to develop multiple custom concretes designed to replicate the stucco finish, grouted masonry, and brick joints on the existing barracks. In conjunction with two types of thin set brick, a split-face concrete masonry unit formliner, and plant-applied projecting windowsills, the exterior precast concrete panels blended seamlessly into the surrounding infrastructure.

While the housing structure was not required to be 75-year life building, the intent was to create a durable structure in a timely fashion, which would not have been achieved with anything other than precast concrete.

“To comply with progressive collapse proved both challenging and complicated and required in-depth calculations and elaborate detailing to achieve mandated progressive collapse requirements,” recalls Anvari. Ultimately, Fort Gordon is slated to become an operational installation where U.S. soldiers will train and fight through cyber, signal, and military intelligence and reside in an equally secure housing facility. ●