The United States Army Corps of Engineers (USACE) is facing numerous challenges to execute successfully our Fiscal Year 2006 Military Construction (MILCON) program. These challenges include impacts stemming from Army Transformation, Integrated Global Positioning and Basing Strategy (IGPBS), Global War on Terrorism (GWOT), Base Realignment and Closure (BRAC), and USACE 2012 Implementation. Recent feedback from Major Subordinate Commanders (MSCs) and our customers revealed the need for USACE Military Programs to develop a focused Military Construction Execution Plan for FY06 to address these challenges and be better prepared for workload anticipated for FY07 and beyond. Construction dollars for the Army MILCON program will increase from the present rate of approximately $1 billion/year to approximately $4 billion/year. In order to execute this tremendous increase in construction dollars and the need to have these projects completed in the shortest possible time, the design-build process will be heavily utilized as one of the available delivery methods.
The design-build process is nothing new to the USACE. The Corps and its contractors have used it with great success in the past. However, in recent years, the incorporation of the Department of Defense (DoD) Minimum Antiterrorism (A/T) Standards has complicated matters as our Architect/Engineers (A/E) executing our designs and the contractors constructing our buildings must be educated about these standards. In 1999 a Security Engineering Working Group (SEWG) was established to develop these standards. The SEWG consists of representatives from Army, Navy, Air Force, and many other DoD agencies. The SEWG developed and issued interim standards in 1999. In 2002, the SEWG issued final Unified Facilities Criteria, UFC 4-010-01DoD Minimum Antiterrorism Standards for Buildings, under the direction of the Under Secretary of Defense.
All of the UFCs for security engineering can be found at the Whole Building Design Guide web site http://wbdg.org/. Once there, click on the DoD Seal in the right margin and the link to the UFCs.
The incorporation of these A/T standards starts well before the Request for Proposal (RFP) for the design-build project is advertised. Each project starts with UFC 4-020-01 Security Engineering Planning Manual. This manual analyzes the assets in the building as well as the associated threats against those assets. One of those assets is military as well as civilian personnel in that structure. The results of the asset/threat analysis will determine if the minimum A/T standards apply or if a more robust structure is required.
The SEWG continues develop detailed design manuals to compliment UFC 4-020-01 Security Engineering Planning Manual. There are approximately 22 of these companion manuals that are already complete or are scheduled to be complete over the next year and a half.
For the sake of simplicity for this article, we will be talking primarily about UFC 4-010-01 DoD Minimum Antiterrorism Standards for Buildings and UFC 4-010-02 Design (FOUO): DoD Minimum Standoff Distances for Buildings. The second listed manual is only available to A/E firms and contractors currently under contract with DoD. An A/E or contractor bidding on a project will not have this UFC available to them until they have been selected as the successful bidder. This manual includes explosive charge weights to be used if minimum standoff distances cannot be met. So the challenge for a potential bidder might be that their building configuration encroaches on the minimum standoff distance and they need to know these charge weights in order to compensate. As a result, the RFP must clearly convey the minimum standoff and specify explosive design pressures for a series of reduced standoff distances.
The main questions the design-build contractor should be asking are what are the minimum A/T standards and how do they affect the cost of the structure? First let’s look at the minimum A/T standards contained in UFC 4-010-01. There are 22 standards and 17 recommendations contained in the UFC. There is no waiver authority for the 22 standards. Any standard that cannot be met must be mitigated in some manner. Of the 22 standards, the three that are most costly are Minimum Standoff Distances; Progressive Collapse Avoidance; and Windows, Skylights, and Glazed Doors. The remaining 19 standards are pretty easily met and add minimal cost to the building.
Standard 1. Standoff Distances. Standoff distances for parking and roadways are based on the assumption that there is a controlled perimeter at which larger vehicle bombs will be detected and kept from entering the controlled perimeter. Where there is a controlled perimeter, Figure 1 applies. If there is no controlled perimeter, assume that the larger explosive weights upon which the controlled perimeter standoff distances are based can access parking and roadways near buildings. Therefore, where there is no controlled perimeter, Figure 2 applies. Measure the standoff distance from the closest edge of parking areas and roadways to the closest point on the building exterior or inhabited portion of the building. A more detailed discussion of this standard can be found in UFC 4-010-01.
Standard 6. Progressive Collapse Avoidance. Progressive collapse is considered to be a significant risk for buildings of three or more stories (Figure 3). Basements will be considered stories if they have one or more exposed walls. For all new and existing inhabited DoD buildings of three stories or more, regardless of the standoff distance provided, design the superstructure to sustain local damage with the structural system as a whole remaining stable and not being damaged to an extent disproportionate to the original local damage. Competent structural engineers who engage in design work typical or similar to DoD facility design can address the design requirements necessary to reduce the potential of progressive collapse. A more detailed discussion of this standard can be found in UFC 4-010-01. Progressive collapse requirements are detailed in UFC 4-023-03, Design of Buildings to Resist Progressive Collapse.
Standard 10. Windows, Skylights, and Glazed Doors. To minimize hazards from flying glass fragments, glazing for windows, skylights, and glazed doors must work as a system to ensure that their hazard mitigation is effective. These provisions apply even if the standoff distances are met or exceeded. Glazing shall be designed in accordance with ASTM F2248, “Standard Practice for Specifying an Equivalent 3-Second Duration Design Loading for Blast Resistant Glazing Fabricated with Laminated Glass” (Figure 4). The laminated glass design is determined by using the provisions of ASTM E1300 “Standard Practice for Determining Load Resistance of Glass in Buildings.” When laminated glass is used to comply with this standard do not use less than 6-mm (.25-inch) nominal laminated glass for all single pane exterior windows, skylights, and glazed doors. The 6-mm (.25-inch) laminated glass consists of two nominal 3-mm (.125-inch) annealed glass panes bonded together with a minimum of a 0.75-mm (0.030-inch) polyvinyl-butyral (PVB) interlayer. For insulating glass units, use 6 mm (.25 inch) laminated glass for the inboard pane as a minimum. Window and skylight frames, mullions, and sashes and door rails and stiles of aluminum or steel shall meet the requirements of ASTM F2248. A more detailed discussion of this standard can be found in UFC 4-010-01.
Just how much do these minimum standards increase the cost of a conventional structure? Recent studies indicate that where there is adequate standoff, incorporation of these 22 standards have a minimal cost increase of three to five percent. For a new structure, incorporation of these 22 standards into a typical project can usually be easily met. If all standards can be met, typical construction including wood and steel studs can be utilized. If a standard cannot be incorporated, then it must be mitigated in some manner. One of the most expensive standards requiring mitigation is standoff. If standoff cannot be met, it will be necessary to design the building for pressures from a potential explosion. This higher pressure may negate the use of conventional construction and require a more robust structure that may be cost prohibitive in some instances.
To reiterate, all DoD MILCON projects since September 2002, regardless of contracting method, require the incorporation of UFC 4-010-01, DoD Minimum Antiterrorism Standards for Buildings. If the 22 standards can be incorporated into the structure, minimal cost is added to its baseline cost. Mitigation costs if Minimum Standoff Distances can not be met can be quite large and may make the project cost prohibitive.
Peter J. Rossbach, Jr., P.E., is a Structural Engineer with Security Engineering responsibilities for the Headquarters, U.S. Army Corps of Engineers. Mr. Rossbach has over 31 years’ experience as a Structural Engineer. He is a member of the Security Engineering Working Group (SEWG), which is responsible for the development of the DoD Antiterrorism Standards. He may be reached at peter.j. rossbach@hq02.usace.army.mil.