Hardening & Blast Mitigation Brochure

An innovative technology being used on Warriors in Transition barracks at Fort Bragg, N.C., stands to revolutionize force protection for the installation.In August 2008, work began on the former Old Nurses’ Quarters to reno-vate the concrete-reinforced structure into a handicapped-accessible barracks for Soldiers recuperating from injuries sustained during duty. The building is being retrofitted withan innovative fiber-reinforced polymer product designed to strengthen the structure against earthquakes, terrorist attacks and other potential structural damage.The new technology complies withDepartment of Defense design specifica-tions UFC 4-010-01, DoD MinimumAntiterrorism Standards for Buildings, and UFC 4-023-03, Design of Buildings to Resist Progressive Collapse, for facili-ties taller than two stories. FRP is a very durable, lightweight composite material constructed from fiberglass or carbon fiber for the purpose of repairing and reinforcing concrete, masonry, wood and steel structures. The material, which resembles wallpaper, is flexible, versatile and easily adheres to most surfaces and shapes — including walls, beams, columns, slabs, steel girders, pipes and utility tunnels. FRP requires no special equipment to apply and, at only one-twentieth of an inch thick, can fit in tight or difficult-to-access areas or around columns without adding bulk.FRP is also leak-proof, corrosion resis-tant and able to withstand the sametemperature variance as conventionalconstruction materials. When it comes to strength, however, the material is matchless. Nearly three times stronger than steel, a five-inch wide strip of car-bon fiber FRP is designed to withstand 75,000 pounds of tensile force, com-parable to a five-eighths inch diameter piece of rebar.Retrofits on the Warriors in Transi-tion barracks are being performed by QuakeWrap Inc.In standard construction, a floor isdesigned to bear pressures pushing downon its surface, called gravity loads, but isextremely vulnerable to an upward exertion of force, such as those typical with blasts, said Mo Ehsani, founder of QuakeWrap.“That was not a consideration in theoriginal design, so most existing build-ings do not have proper steel reinforce-ment in the right locations to take that type of upward pressure,” Ehsani said. “It’s just something nobody at the time these buildings were being designed had given any consideration.”To upgrade the structure to meet thenew standards, FRP is being applied to the slab surface and underside of each of the barracks’ three floors and attic. It is also being applied to the building’s columns to improve their structural in-tegrity in tension as well as compression.While the material is designed to fortify a building in the event of a natu-ral disaster or terrorist attack, Ehsani stressed that the ultimate goal is not to prevent structural damage but to limit any localized damage incurred from causing an entire structural collapse.“[If a building is compromised,] dam-age is going to occur and sometimes thebuilding may not be usable afterwards,but the point of concern is human safety,” he explained. “The attempt in all of these retrofits is to make sure that the building remains up so that people can get out safely.”While FRP retrofitting is a relativelynew concept for Fort Bragg and NorthCarolina, the material’s exceptional ability to inhibit progressive collapse is gaining widespread popularity in areas particularly prone to seismic activity or terrorist interest, such as federal build-ings and courthouses, facilities in Wash-ington, D.C., and U.S. embassies.Because FRP retrofits do not requireadjustments to a building’s foundation,application is noninvasive and can typi-cally be completed in fewer than 75 days. Thus, FRP retrofits stand to substan-tially reduce overall project costs and environmental impacts by circumvent-ing the need for major demolition and reconstruction and its associated wastes. In addition, retrofits can be performed while the building is occupied, allowing operations to continue without interrup-tion.While the Warriors in Transition barracks are the first facility on Fort Bragg to receive FRP retrofits, the future implications of this method are many. As funding becomes available, similar retrofits may be considered for future projects, such as the Old Post District and the XVIII Airborne Corps Head-quarters.POC is Nathaniel Hermann, resident engineer, Army Corps of Engineers, 910-396-9977,nathaniel.j.hermann@usace.army.mil.Erin Barstow is the community resource coordina-tor, Directorate of Public Works, Fort Bragg.FRP is a durable, wallpaper-like material nearly three times stronger than steel that fits easily around columns without adding bulk. Photo by Nathaniel HermannFort Bragg barracks receives pioneering force protection retrofitby Erin Barstow28 PUBLIC WORKS DIGEST • MAY/JUNE 2009Columns • Beams • Corrosive Environments • Pipes • Floors • Walls • Slabs • Underwater Piles(866) QuakeWrapQuakeWrap.com®®Acronyms and AbbreviationsDoD Department of DefenseFRP fiber-reinforced polymerSam JadaliHighlightSam JadaliHighlightSam JadaliHighlightSam JadaliHighlight