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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation 2 Information and Technology Needs of Stakeholders One purpose of the workshop “Protecting People and Buildings from Bomb Damage” was to bring together representatives of the various stakeholder groups to identify their needs for information and technology to improve the blast-resistance of buildings and reduce the likelihood of death and injury in the event of a terrorist bombing attack. During the course of the presentations and in the topical breakout sessions, workshop participants identified many issues of the civilian user community (and to a lesser extent the defense community). Some of the technology and information needed requires additional research (e.g., to address the performance of glazing materials and structural subassemblies in a blast environment), but other needs could be met by empirical studies of existing information (e.g., analysis of prior bombing events) or by adapting for civilian use design methods and approaches already developed for the military and documented in government manuals and design guides. A technology transfer strategy that links needs with proposed solutions is presented in Chapter 3. Specific information and technology needs discussed at the workshop are presented below, organized according to the four stakeholder groups identified by the committee as the primary beneficiaries of the results of the Blast Mitigation for Structures Program—owners and users of buildings and facilities; building system (mechanical, electrical, and other) designers; structural designers; and emergency medicine and search and rescue personnel.
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation OWNERS AND USERS Even though more than 250 bombing attacks against buildings were reported in 1997 (FBI, 1998), there had been, until the events of September 11, 2001, no recurrence of a domestic event of the magnitude of the bombing of the Alfred P. Murrah federal building in 1995. Whether in the public or private sector, most building owners and users still view the threat to domestic buildings from terrorist bombings as a high-consequence, low-probability event and thus find it difficult to provide and pay for the protective counter-measures suggested by threat and vulnerability analyses. Persuading decision makers to allocate resources to address potential threats from terrorist bombings is not a simple task. In the rare instance when a public or private sector building owner accepts the need for security measures against terrorist bombing threats, it is highly unlikely that resources will be available to fund all desirable measures or insurance credits provided to underwrite their cost. For several reasons, the insurance industry is not likely to provide incentives for blast-mitigating building design, despite intuitive logic to the contrary. Losses from terrorist attacks have been very low in experience, and insurers are thus less likely to offer significant credits for well-protected risks. In addition, property insurance generally covers direct losses due to a terrorist attack—most specifically the cost of repairing or replacing the building. It has not covered difficult to quantify collateral losses such as lost market share, damage to corporate or product image, or loss of employee productivity during recovery, which can account for the largest potential economic impact on an affected property. To overcome such barriers to increased support for blast-mitigation building design, many workshop participants suggested that research on blast-mitigation technology should maintain a broad perspective, focusing on blast-mitigation solutions that can be shown to apply to other hazards and that thus could be more readily accepted and deployed. Specific suggestions included the following: Ensuring that design measures for mitigation of blast effects are effective in other areas such as fire and life safety; Developing designs that can enhance survivability and facilitate emergency response in disasters of various kinds by, for example, providing buildings that can be used as areas of refuge or safe havens in the aftermath of blasts, fires, earthquakes, tornados, hurricanes, and other classes of emergencies; and Providing education and a rationale for building code authorities to include consideration of blast effects in code provisions where
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation these are consistent with the objectives of building and fire and life safety codes. Although it is improbable that commercial building codes will mandate security and blast-effects mitigation measures, it would be appropriate for a code to stipulate that any measures undertaken to address security concerns must meet certain performance standards. Testing laboratories and certifying agencies routinely put forward such criteria, which could include provisions such as a requirement that if blast-resistant windows are installed, some percentage must be operable to permit ready egress for the occupants and access for rescue personnel. Workshop participants also suggested that the Blast Mitigation for Structures Program could investigate other performance objectives such as energy performance, sustainability, and the quality of the working environment that might make blast-effects mitigation measures more financially attractive. Benefit-cost analysis of blast-effects mitigation features could identify ancillary benefits that contribute to long-term savings over the life cycle of the improvements, such as maintenance and operations costs, occupants’ productivity, reduction of occupants’ risk of injury and death, and enhancement of the speed of recovery of the operation to reduce loss-of-use costs. A major issue for building owners and managers, and a significant obstacle to planning the blast-effects mitigation component of a project, is the lack of readily available and accurate cost-estimating methods. This gap was noted in earlier work by the NRC that recommended the following: Analyze all new civilian federal buildings, and existing buildings where appropriate, to determine reasonable ways of incorporating blast-hardening and other blast-effects mitigating features, and to document consequent building construction costs and financial performance. (NRC, 1995) The committee notes that such data would lead owners, designers, and managers to sources of costs and guides for estimating how much different levels of protection would cost. However, to date, the compilation and study of costs from past projects have not been done systematically. BUILDING SYSTEM DESIGNERS Overall, the design community is seeking the development of a unified design approach that incorporates standard criteria for security objectives and a uniform definition of standoff. At the workshop, discussion of building systems also identified the need for a more multihazard design approach and benefit-risk methods to assess the true value of mitigation measures over the lifetime of the building. The phenomena of explosions and collat-
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation eral effects of blast and blast debris, particularly in multiple building configurations, are not well understood by most building system designers. Technical questions arise regarding reflection of the blast wave and how this can affect adjacent buildings. Considerable interest was expressed in how earthquake-resistant designs would perform under blast loading. While blast loading of buildings differs in character from seismic loading, some mitigation principles are applicable under both types of loading. The response of building systems such as water and sewer lines and sprinkler systems appears similar to responses experienced during earthquakes, but the potential of these systems to imperil occupants and impede rescue when they are damaged argues for some definitive statements of expected performance. The Blast Mitigation for Structures Program plans to study the relative performance of standard seismic designs under blast conditions, but little information is yet available. A number of areas that require additional research were identified, such as site perimeter features, openings in a building’s exterior envelope, and the collateral effects of blast and blast debris. Widespread desire was expressed by workshop participants for a better understanding of: Design options for a variety of vehicle barriers; The value of blast barriers in attenuating blasts and sheltering buildings from blast effects; Design for support of the efforts of rescue and emergency services; Techniques for perimeter controls; Design of flexible and movable perimeter-access controls, such as gates and other features; and Retrofitting of features such as bollards to be installed over existing vaults or other underground spaces at the perimeter barrier. Information and guidance are also desired for design options and products for openings in the exterior cladding of a building such as operable sashes, doors, louvers, skylights, and exterior hardware. As noted above, blast and its effects on both structural and nonstructural systems are not well understood by the design community. Questions were raised regarding the vulnerability of columns to smaller satchel-type charges, uplift effects of explosions on slabs, especially in mechanical equipment rooms with louvers, as well as design details for all building systems subject to blast. One strongly expressed need was for simplified procedures that would permit building system design professionals to identify and evaluate blast-effects mitigation options at the early stages of a project, particularly during consultation with the building’s owner.
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation STRUCTURAL DESIGNERS As pointed out at the workshop, structural designers’ needs for information and guidelines parallel many of the issues raised by owners and users and by building system designers. For example, an overriding interest was expressed in obtaining access to guidelines for protective design, with an emphasis on obtaining up-to-date technical design manuals in the public domain that address differing levels of protective structures, especially in the following three categories: Lesser hardening (e.g., industrial and commercial facilities), Moderate hardening (e.g., General Services Administration and courthouses), and Greater hardening (e.g., State Department and Department of Defense facilities). There was considerable interest in simplified design guidance for providing lesser to moderate levels of blast protective design in a cost-effective manner, particularly for retrofit construction. Two additional design issues that were specifically identified were criteria for and approaches to providing reasonable protection against progressive collapse from moderate-size blast events and the entire question of glazing—available materials, and methods for attaching glass to the frame, and the frame to the wall. Test data and access to the database for all products that have been tested to some performance specification are desired. This includes design methods for “hardening” existing masonry walls with such materials as polymer linings (RinoSkin), steel plates, and geotextile fabrics. More information regarding the ductility and effectiveness of various types of mechanical splicing of reinforcing steel when subjected to rapid strain rate loads is also desired. Strong support was expressed for a program of short courses, seminars, and tutorial documents for professionals to enhance their knowledge of blast protective design. This would include basic screening and design approaches for blast-hardened structures as well as pragmatic and cost-effective approaches for preventing progressive collapse. Also discussed was the need for a risk-based methodology to help a building’s owner and design team establish appropriate levels of hardening for a specific project. Such a methodology would establish a minimum desirable set of hardening goals for various types of facilities (i.e., reasonable levels of protective design and the cost of providing it) coupled with guidelines aimed at achieving these hardening goals.
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation EMERGENCY MEDICINE AND SEARCH AND RESCUE PERSONNEL Five major issues affecting emergency medical care and search and rescue operations were identified at the workshop: Perishable injury and health data that could be used to save lives in future incidents is not routinely collected. Obtaining data that has been compiled on past bombings is difficult. Buildings are designed with little consideration for the needs of search and rescue operations and personnel.1 Search and rescue operations are impeded by a general lack of knowledge about a building’s design, utility shut-offs, and the probable locations of occupants and potential hazards. Search and rescue operations would be facilitated by the rapid availability of assessments of a damaged building’s remaining structural integrity. From the standpoint of emergency medicine, bombings constitute a double tragedy. The deaths, injuries, and property damage are obvious first-order effects. However, the failure to collect valuable, perishable data could also result in lives lost needlessly in future events. Several reasons were cited for the general failure to collect data: rescuers, survivors, and bystanders leave the scene; priority is given to administering medical care, not to collecting data; buildings are demolished and occupants relocated. In order to overcome the inherent barriers to collecting and compiling accurate medical data, it was suggested that multidisciplinary, rapid-response data collection teams be established. Such teams could be organized within existing incident response activities carried out by such federal agencies as the Centers for Disease Control and Prevention, the Federal Emergency Management Agency, or the Bureau of Alcohol, Tobacco, and Firearms. These groups would be analogous to the crash investigation teams fielded by the National Transportation Safety Board and would utilize specialists in emergency medical services, epidemiology, structural engineering, architecture, emergency management, and disaster research. They would apply standardized methods to collect data of potential use to medical responders, building designers, and injury prevention specialists. The primary value of this database would be to prepare medical re- 1 For example, design features that might provide protection against bomb damage (e.g., heavily reinforced concrete walls) may greatly impede efforts by rescuers to gain access to victims following an explosion.
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation sponders for the various causes of injury and illness that they might encounter (e.g., blast effects, glass, inhaled dust, shrapnel, structural collapse, smoke, carbon monoxide, asbestos or other toxic inhalants, angina heart attack). However, it would also serve several other purposes. Buildings are currently designed with little consideration for the needs of search and rescue personnel and operations. With better information available, search and rescue personnel would have an improved sense of where survivors seek refuge (or where and how they happen to survive) and how to extricate them quickly and safely. Rescue personnel would also have a better understanding of the hazards they face when entering a damaged building (e.g., unsecured electric and natural gas service, leaking sewage, airborne asbestos, and other hazardous substances). Detailed data on the epidemiology of blast-related injuries would also be of considerable value to the designers of future buildings, who could then use that information in the design and placement of equipment and services, emergency shut-off valves and switches, and areas of refuge and potential escape routes. Furthermore, accurate data on the injuries sustained by a building’s occupants, combined with structural and nonstructural data on the location of victims at the time of an explosion, would be helpful in identifying mechanisms of injury and potential injury-reduction strategies. Overall, this was seen as an area where modest investments in pre-event planning could greatly improve the survivability of the victims of future events. Although some data from past bombing events (in Oklahoma City, at the Khobar Towers, and in Nairobi and Dar es Salaam) have been collected and analyzed, the work has been done by several organizations. Collection methods have varied, as have the level and specificity of the data, which complicates the accessibility of the data and its comparability across events. At an even more basic level, researchers may not be aware of the existence of data from other events. Workshop participants discussed the concept of a national or international clearinghouse to serve as a repository for blast-related injury data from past and future events. The clearinghouse would be of great value to practitioners and researchers in emergency medicine, injury epidemiology, and building design. Data collected promptly and stored in a retrievable form is only part of a solution to a truly multidisciplinary problem—how to use information effectively to reduce injuries, aid recovery, and save lives while, at the same time, not placing emergency personnel at excessive risk of injury, illness, or death. The key to developing and applying a truly holistic approach to safe, robust, and attractive building design is continued dialogue and interaction between medical, building design, and rescue and recovery specialists through conferences, seminars, and short courses. If each specialty understands the needs of the others and how their work affects and is affected by them, an effective system of lessons learned can be implemented.
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Protecting People and Buildings from Terrorism: Technology Transfer for Blast-effects Mitigation REFERENCES FBI (Federal Bureau of Investigation). 1998. 1997 Bomb Summary. FBI Bomb Data Center, General Information Bulletin 97-1. Washington, D.C.: U.S. Department of Justice. NRC (National Research Council). 1995. Protecting Buildings from Bomb Damage: Transfer of Blast-Effects Mitigation Technologies from Military to Civilian Applications. Washington, D.C.: National Academy Press.
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