International Concrete Abstracts Portal

Hardening structures against weapons effects has been, until recently, of concern almost exclusively of the military. However, with the increase of terrorist activities directed against civilian targets, there is a growing interest in applying these principles to the design of non-military structures. A design approach is presented for civilian structures subject to an external explosion. The issues addressed are threat assessment, countermeasures, weapons effects, analytical techniques, and optimization techniques used. Introduction In military terminology, terrorism is considered low-grade warfare. As such, many of the principles used to design military targets are applicable to the protective design of civilian targets subject to terrorist attack. However, the objectives of design are different for civilian targets. For military facilities the primary objective is to maintain function after attack. ‘Function’ refers to essential activities such as launching a missile or maintaining communications or intelligence. For civilian facilities the primary objective is to save lives while preserving the non-military character of the facility; maintaining function becomes a secondary issue. Because of this difference, protective design principles need to be reevaluated. In this paper the fundamental principles of military facility design are used to develop a rational approach to the design of new civilian structures. These ideas are also applicable to the retrofit of existing structures. This paper is partially based on work done for the Foreign Buildings Office of the US Department of State in developing engineering guidelines for protecting US embassies abroad. Threat and Countermeasures There are many possible threats to be considered in the design of civilian structures (Fig. 1). Some threats are excluded, such as aerial attack or nuclear attack because they are impractical to design for. Other threats are not

The number of blast resistant facilities planned, designed, and constructed recently in petrochemical plants points to an increased interest in this specialized type of design. This paper deals with the numerous decisions to be made in designing blast resistant buildings. First, the need for a blast resistant design must be evaluated. Then, design objectives and relative cost must be balanced to produce an optimal design. Design practices must be established as there are various company, military, and professional publications available. Detailing practices also require careful consideration as there are differences in the implementation of shear reinforcing, precast elements, penetrations, and exterior doors. Several actions would greatly benefit the design of petrochemical blast facilities. A clear definition from government and insurance sources is needed on what facilities need to be protected from explosions. Improvements are needed in the evaluation of blast loads within petrochemical facilities. A consensus on engineering calculations and construction details would help unify design approaches.

Nuclear newer plant structures, systems and I components may be subject to a variety of impulsive loads caused by accidental explosions and or high energy pipe ruptures. Examples of such loads are jet impingement, reactor vessel sub-compartment pressurization, pipe whip restraint reaction and blast pressure. Various US NRC Regulatory Guides and Standard Review Plans specify required loads and provide acceptable methods for structural design. The design of concrete structures, subject to impulse and impact loads is governed by the ACI-349 Code. Acceptable analysis techniques vary from simplified quasi-static methods for single degree of freedom systems, to detailed computer analysis techniques accounting for material and geometric non-linearities. This paper reviews briefly the impulsive loads and the procedures for analyzing a n d designing structures found in nuclear facilities.

This paper discusses the historical development of design criteria for blast resistant buildings in the petrochemical industry, including static vs. dynamic design requirements for control rooms, and TNT equivalence vs. VCE models for quantifying blast loads. Existing industry guidelines for the siting and design of plant buildings are reviewed. A methodology and examples are presented for the categorization, design and structural evaluation of building components for blast resistance

There are a number of existing facilities at petrochemical plants which : house a significant number of personnel as well as expensive control equipment which must provide protection during an explosion accident. Many of these structures are not capable of resisting blast pressure which may occur during an explosion because they were not designed for these loads. As a result, the potential for significant hazards to personnel and equipment exists at many plants. This paper describes a project involving the scenario postulated above. The existing building was constructed of unreinforced masonry yet was subjected to peak reflected blast loads on the order of 70 psi (483 kPa). A poured-in-place, reinforced concrete box was selected for the new structure. Walls were designed to resist reflected blast loads in flexure and to transmit reactions to the roof diaphragm and shear walls. Walls and roof sections were designed using single-degree-of-freedom (SDOF) methods for determination of dynamic response to the transient blast load. Control conduits extending from the existing walls presented several difficulties for construction of the new walls. A confined working area, high water table, and a requirement for equipment to remain operational also posed unique design challenges.